Issued Jurul4, ,1911. 
 
 U. S. DEPARTMENT OF j\GRICULTURg, 
 
 BUREAU OF ANIMAL INDUSTRY. BULLETIN 130. & 
 
 =- <4 
 
 A. D. MELVIN, CHIEF OF BUREAU. 
 
 JDIES ON THE BIOLOGY OF 
 THE TEXAS-FEVER TICK. 
 
 BY 
 
 H. W. GRAYBILL, 
 
 Assistant Zoologist, Zoological Division, 
 Bureau of Animal Industry. 
 
 UNIVERSITY OF CALIFORNIA* 
 LOS ANGELES 
 
 SEP 23 1952 
 
 LIBRARY 
 GOYT. PUBS. ROOM 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 1911.
 
 Ksm-il June 14, 1911. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY. BULLETIN 130. 
 
 A. D. MELVIN, CHIEF OF BUREAU. 
 
 STUDIES ON THE BIOLOGY OF 
 THE TEXAS-FEVER TICK. 
 
 BY 
 
 H. W. GRAYBILL, 
 
 Assistant Zoologist, Zoological Division, 
 Bureau of Animal Industry. 
 
 WASHINGTON: 
 GOVERNMENT PRINTING OFFICE. 
 
 1911.
 
 THE BUREAU OF ANIMAL INDUSTRY. 
 
 Chief: A. D. MELVIN. 
 Assistant Chief: A. M. FARRINGTON. 
 Chief Clerk: CHARLES C. CARROLL. 
 
 Animal Husbandry Division: GEORGE M. ROMMEL, chief. 
 Biochemic Division: M. DORSET, chief. 
 Dairy Division: B. H. RAWL, chief. 
 
 Inspection Division: RICE P. STEDDOM, chief; MORRIS WOODEN, R. A. RAMSAY, 
 and ALBERT E. BEHNKE, associate chiefs. 
 
 Pathological Division: JOHN R. MOHLER, chief. 
 Quarantine Division: RICHARD W. HICKMAN, chief. 
 Zoological Division: B. H. RANSOM, chief. 
 Experiment Station: E. C. SCHROEDER, superintendent. 
 Editor: JAMES M. PICKENS. 
 
 ZOOLOGICAL DIVISION. 
 
 Chief: B. H. RANSOM. 
 
 Assistant Zoologists: ALBERT HASSALL, HARRY W. GRAYBILL, and MAURICE C. HALL. 
 
 Junior Zoologists: HOWARD CRAWLEY and WINTHROP D. FOSTER.
 
 LETTER OF TRANSMITTAL. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY, 
 
 Washington, D. C., September 28, 1910. 
 
 SIR: I have the honor to transmit for publication the accompanying 
 manuscript entitled "Studies on the Biology of the Texas-fever 
 Tick," by H. W. Graybill, assistant zoologist in the Zoological Divi- 
 sion of this bureau. 
 
 A large number of publications have been issued from time to time 
 regarding the investigations of this bureau concerning the Texas- 
 fever tick and its disastrous effect upon the cattle industry of the 
 South, and the extermination of the parasite has in recent years 
 been vigorously pushed both by the Federal Government and the 
 several States involved. In order that this work of extermination 
 may be the more intelligently and successfully carried out it is 
 necessary that it should be based upon the most accurate knowledge 
 possible of the life history, habits, etc., of the tick. Accordingly 
 the experiments herein described were projected in order to add 
 further information relative to certain biological features of the tick 
 which may have a bearing upon the eradication work. The experi- 
 ments were carried out in cooperation with the veterinary depart- 
 ment of the Alabama Polytechnic Institute, at Auburn, Ala. 
 
 I recommend that the paper be published in the bulletin series of 
 this bureau. 
 
 Respectfully, A. D. MELVIN, 
 
 Chief of Bureau. 
 
 Hon. JAMES WILSON, 
 
 Secretary of Agriculture.
 
 CONTENTS. 
 
 Page. 
 
 Introduction 7 
 
 Historical 7 
 
 Methods of study 9 
 
 Periods of the nonparasitic portion of development 12 
 
 The preoviposition period 12 
 
 The oviposition period 13 
 
 Incubation period 14 
 
 Hatching period 15 
 
 Longevity period 16 
 
 Total time of nonparasitic development 17 
 
 Number of eggs laid and percentage hatched 18 
 
 Experiments with horizontal tubes 19 
 
 Records obtained from the field plots 20 
 
 Per cent of females ovipositing 22 
 
 Effect of immersion in water on engorged females 23 
 
 The influence of moisture on the incubation period 23 
 
 Periods in the parasitic portion of development 24 
 
 Observations on the movement of ticks after the first and second molt 26 
 
 . Change of location after first molt 26 
 
 Change of location after second molt 27 
 
 Early distinguishing of female nymphs by males 27 
 
 Experiments in transferring ticks on cattle 27 
 
 Experiments in rearing unfertilized females 29 
 
 The occurrence of dead ticks on cattle 31 
 
 Host relations of the cattle tick 31 
 
 Infestation experiments on rabbits 32 
 
 Infestation experiments on a cat 33 
 
 Infestation experiment on a dog 33 
 
 Infestation experiments on sheep 33 
 
 The natural occurrence of the cattle tick on sheep 34 
 
 The progeny of females matured on sheep noninfectious 36 
 
 Man as a host of the tick 37 
 
 Bibliography 3S 
 
 Appendix: 
 
 TABLE 1 . Individual records of ticks used in experiments 40 
 
 TABLE 2. Data on parasitic development of ticks on animals 42 
 
 5
 
 ILLUSTRATIONS. 
 
 Page. 
 FIG . 1 . Vertical tube used for incubating eggs of tick 3 9 
 
 2. Horizontal tube used for incubating eggs of ticks 10 
 
 3. Arrangement of field plot for incubating tick eggs under outdoor con- 
 
 ditions 12 
 
 6
 
 STUDIES ON THE BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 INTRODUCTION. 
 
 The eradication of the cattle tick ( Margaropus annulatus) from the 
 States below the quarantine line has been shown to be entirely feasible 
 as a result of the work carried on during the past five years by the 
 Bureau of Animal Industry in cooperation with the State authorities. 
 The work of extermination must, obviously, be preceded by and based 
 upon a knowledge of the life history of the tick, its habits, and the 
 manner in which it is affected by climatic and other environmental 
 conditions. 
 
 In order to supply possibly useful data relative to the biology of 
 the tick, additional to that already collected by different observers, 
 a series of investigations was arranged for and carried out under 
 cooperation between the Zoological Division of this bureau and the 
 veterinary departhient of the Alabama Polytechnic Institute at 
 Auburn, Ala. In the observational part of these investigations, the 
 results of which are recorded in the present paper, the writer was 
 assisted by Mr. W. M. Lewallen. Some of the results of the work at 
 Auburn have been briefly mentioned in an earlier paper (Graybill, 
 1909) 10 . a 
 
 HISTORICAL. 
 
 Up to the time that Dr. Cooper Curtice 2 (1891) of this bureau 
 established the fundamental facts in the life history of the cattle tick 
 it was commonly assumed that the life history of this species corre- 
 sponded to that of certain other ticks, which fall from their host 
 before shedding their skins in transforming from one stage to another. 
 Curtice, however, showed that the cattle tick remains on the host 
 from the time it attaches as a larva until it falls as an engorged 
 female to deposit its eggs, and established other facts relative to the 
 duration of some of the periods in the life cycle and the changes in 
 structure occurring at the time of the first and second molts, which 
 were supplemented in a second paper 3 (1892) by further data concern- 
 ing the life history, habits, and structure of the tick. Smith and 
 Kilborne 22 (1893), who were the first to demonstrate and prove the 
 connection between the tick and Texas fever, published a number 
 
 a Citations to literature are given In bibliography on page 3S. 
 89053 Hull. 13011 2
 
 8 BIOL.OGY OF THE TEXAS-FEVER TICK. 
 
 of important facts on the biology of this parasite, and Schroeder 18 > 19 
 (1900 and 1907) and Schroeder and Cotton 20 - 21 (1900 and 1907) in 
 several articles issued by this bureau have presented considerable 
 data bearing on the life history of the tick and its relationship to the 
 disease which it transmits. Curtice 5 (1896) was among the first to 
 urge the undertaking of eradication measures, and (1897) 6 was the 
 first to show how cattle could be freed from, ticks by rotation methods. 
 Doctor Curtice's work in North Carolina, continued by Dr. Tait 
 Butler, clearly demonstrated at an early date the feasibility of tick 
 eradication, which has been fully confirmed by the experience of the 
 more extensive campaign now under way in various parts of the 
 tick-infested area. 
 
 Several investigators connected with State experiment stations have 
 studied the tick with reference to its life history. Dinwiddie 8 (1892), 
 of the Arkansas Experiment Station, was an early investigator, who 
 more recently (1908) 9 has published further observations. Morgan 
 (in Dalrymple, Morgan, and Dodson, 7 1898) reported investigations 
 conducted in Louisiana having to do with various stages of the 
 tick, especially with regard to the influence of heat, cold, and light 
 and the effects of water upon the tick and its eggs. Later the same 
 author 14 ' 15 (1903, 1905) discussed and emphasized the practicability 
 of freeing cattle and pastures of ticks by following pasture-rotation 
 methods based upon known facts in the life history. 
 
 Newell and Dougherty 16 (1906), of the State Crop Pest Commission 
 of Louisiana, made a comprehensive study of various periods in the life 
 cycle, obtaining valuable data on the duration of the incubation period 
 and the vitality of the larvas, at different times of the year. Their 
 work was conducted at Baton Rouge, La., and they formulated a 
 pasture-rotation method for ridding cattle and farms of ticks, adapted 
 to conditions prevailing in Louisiana. Cotton 1 (1908), of the Ten- 
 nessee Experiment Station, has published life-history notes based on 
 investigations conducted at Knoxville, Tenn., and has suggested a 
 number of rotation methods for tick eradication. 
 
 Recently the Bureau of Entomology of this department has under- 
 taken life-history studies of the tick and has issued Bulletin 72, by 
 Hunter and Hooker 12 (1907), in which are incorporated the results of 
 comprehensive investigations conducted by these authors at Dallas, 
 Tex. The results obtained by these investigators are confirmatory of 
 the earlier work of the Bureau of Animal Industry and other observers, 
 and in addition have largely increased our knowledge of the biology 
 of the tick, supplying data concerning all stages of development, 
 time required for the completion of these stages at different seasons 
 of the year, and the influence of variations in environment, together 
 with suggestions for the practical application of the information given. 

 
 THE EGG INCUBATION TUBES. 
 
 METHODS OF STUDY. 
 
 The plan pursued in determining the incubation period of dggs and 
 the longevity of seed ticks in the investigations at Auburn was essen- 
 tially that followed by Newell and Dougherty 1 " :100G). A number 
 of engorged females were collected at the beginning of each month. 
 After oviposition began the eggs laid by each tick were removed at 
 the end of every 24 hours. After they were counted each lot was 
 placed in an incubation tube marked with the date when removed 
 and a number indicating the tick which deposited them. Careful 
 observations were made on the tubes and a record was kept of the 
 time when the eggs in each tube began to hatch and when the 
 hatching was completed, also when the larva 1 
 began to die and when all of them were dead. 
 
 At the outset of the work the incubation tubes 
 used were test tubes of the type employed in 
 bacteriological work. These were filled half full 
 of moist sand. A cardboard disk cut so as to 
 fit the tube was pressed down on the sand. On 
 top of this was placed a small cube of cork, and 
 on the latter was placed another disk similar to 
 the first. The eggs were placed on the upper 
 disk. It was found necessary to use these disks 
 in order to prevent the eggs and seed ticks from 
 becoming mixed with the sand, which would have 
 rendered observation very difficult and also 
 would have made the counting of the unhatched 
 eggs and dead seed ticks, for the purpose of deter- 
 mining the percentage of eggs hatching, an almost 
 impossible task. Furthermore, if only one disk 
 is used the development of the eggs is frequently 
 endangered by the growth of mold. When the 
 two are used, separated in the manner indi- 
 cated, mold frequently grows on the lower one, 
 but does not often attack the upper one in 
 such a manner as to endanger the eggs. 
 
 These tubes, however, were not found entirely 
 satisfactory on account of the fact that there 
 
 was no practicable way of adding more water to the sand and thus 
 keeping the tube supplied with moisture. To obviate this defect a 
 new tube was devised which was found very satisfactory in most re- 
 spects (see fig. 1). It is so constructed that it is possible to add 
 water to the sand at any time. The new tubes are made of glass 
 cylinders 11.5 cm. long and about 20 mm. in outside diameter. 
 One end of the cylinder is closed by a cork, pierced in the middle by a 
 
 FIG. ]. Vertical tul>e u 
 for incubating ejrtrs 
 ticks.
 
 10 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 hole about 5 mm. in diameter. Into this opening is fitted one 
 arm of a piece of glass tubing bent in the form of a hook. This 
 arm should be long enough to pass through the cork and the 
 bend should be just so broad that the long arm runs up close to the 
 outside of the glass cylinder. The long arm should reach to about 
 the middle of the tube. Water is added through this portion of the 
 tubing. The cardboard disks are arranged in the same manner as 
 in the test tubes previously described, the only modification necessary 
 being to pierce the disks with a needle in order to permit the escape 
 of air from below upward when water is added. In case the short 
 arm of the tubing becomes clogged with sand the tubing is easily 
 removed and flushed out with water. The incubation tubes were 
 closed on top by means of muslin held in place by rubber bands. 
 Cheese cloth is not satisfactory for this purpose, being so loosely woven 
 that the larvse escape through the openings. 
 
 During the course of the work a much simpler method than the 
 above for obtaining records on the nonparasitic stages of the tick 
 
 FIG. 2. Horizontal tube for incubating eggs of ticks. 
 
 was devised. In this method a horizontal tube is used (see fig. 2). 
 This is made of a glass cylinder like that described above. A cork is 
 inserted in one end. On the bottom of the cork a rectangular piece 
 of cardboard is fastened so that one of its Jong sides projects a little 
 beyond the edge of the cork and serves as a support for the tube, 
 preventing it rolling from side to side. The tube contains a tray 
 constructed as follows: A rectangular piece of rather thick paper, 
 with a width equal to one-half the inside circumference of the tube 
 and a length equal to the internal length of the tube, is provided 
 for the bottom and. sides. The ends are made of thin disks of cork 
 having a diameter a little less than the internal diameter of the tube. 
 The rectangular piece of paper is rolled into a half cylinder and the 
 cork ends are pinned or glued into position, each tilting a little 
 toward the other. One of the disks is placed some little distance from 
 the end of the tray, a fingerhold being thus afforded for withdrawing 
 it from the tube. The end of the tube is covered with a piece of 
 muslin.
 
 METHODS OF STUDY. 11 
 
 This particular form of horizontal tube was kept when in use 
 beneath a bell jar supplied with moisture. Another variety with 
 sand in the end next the cork and fitted with a piece of glass tubing 
 for the addition of w r ater, as in the vertical incubation tubes, was also 
 used. These latter tubes furnished conditions practically identical 
 with those in the vertical tubes. Various modifications of these 
 horizontal tubes were used, some being made of ordinary test tubes, 
 but they are hardly of sufficient importance to be described here. 
 
 The method of using the horizontal tube is as follows: An en- 
 gorged female is placed in the tray, which is put in the tube. The 
 tilted ends prevent the tick from crawling up. After oviposition 
 begins the tick moves slowly backward, leaving a long mass of eggs 
 in front of it. When oviposition is nearly completed the female is 
 removed from the eggs to the opposite end of the tray, so as to facili- 
 tate observation of the remainder of the process. The newly laid 
 eggs are removed from her each day and placed at the end of the egg 
 mass until oviposition is completed. The hatching proceeds along 
 the mass of eggs until the last hatch, unless, as sometimes happens, 
 there is a displacement of the eggs. The dates when the female was 
 collected, when oviposition began and ended, when hatching began 
 and was completed, and when the first and the last larvae died are 
 recorded. This method requires such a small amount of time daily 
 in attending to the tubes that a very large number of ticks can be 
 kept under observation at one time and under various conditions. 
 
 For the purpose of checking the results obtained in the tubes 
 indoors, experiments were conducted outside in sunny and shady 
 places presenting ordinary pasture conditions. In these experiments 
 small plots in a pasture were used (fig. 3). Each plot consisted of 
 an area 2 feet square inclosed by boards 3 inches wide set edgewise. 
 In the center of the plot an ordinary cigar box with the lid and bottom 
 removed was sunk halfway into the turf. This was done so -as to 
 confine the female ticks and thus facilitate observation on them. 
 The box was provided with a cover made of screen wire, which, during 
 the progress of the experiment was covered over with dead leaves 
 or other litter. The plots were protected from surface drainage by 
 properly arranged ditches. Each was surrounded by a fence of wire 
 netting to keep out animals. There were two series of these plots, 
 one in a place shaded by trees for a part of the day and the other in 
 an unshaded place. 
 
 The indoor experiments were conducted in an unheated room with 
 the windows open at all times as high as was practicable. The tem- 
 perature and humidity were thus made to correspond very closely 
 to outdoor conditions. 
 
 The experiments in the plots were run parallel with the indoor 
 experiments Usually two plots were started at the beginning of
 
 12 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 each month. Ordinarily 10 engorged ticks were confined in the 
 box described above and observations were continued on each plot 
 until it became free of seed ticks. 
 
 PERIODS OF THE NONPARASITIC PORTION OF DEVELOPMENT. 
 
 The various periods in the nonparasitic portion of the development 
 of the tick which will receive consideration in the following pages are, 
 the preoviposition period, the oviposition period, the incubation 
 period, the hatching period, and the longevity of the larvae; also the 
 
 FIG. 3. Arrangement of field plot for Incubating tick eggs under outdoor conditions. 
 
 entire period from the time the female drops until all the larvae are 
 dead. Unless otherwise specified the records given hereafter refer 
 to the experiments in the vertical tubes. 
 
 THE PREOVIPOSITION PERIOD. 
 
 This period, so named by Hunter and Hooker 12 (1907, p. 14), 
 extends from the time the female tick drops until she begins to 
 oviposit. Its duration was found to vary greatly for the different 
 months of the year, depending largely on the temperature. The 
 average length of the period, as shown in the following tables, ranged 
 from 3 to 49.3 days. The maximum period observed was 98 days 
 and the minimum 1 day. The latter is not included in the tables,
 
 THE OVIPOSTTION PERIOD. 
 
 13 
 
 as it was observed outside the course of the regular experiments. It 
 occurred in the case of a moderate-sized tick collected April 29, 190X, 
 which had been placed in a flask along with some others. 
 
 During the preoviposition period the ticks under observation were 
 kept either in petri dishes, the bottoms of which were lined with 
 paper, in pasteboard boxes, or in horizontal tubes. The results 
 obtained relative to the preoviposition period, arranged according to 
 the months during which the ticks were collected, are given in the 
 following tables: 
 
 Preoviposition period Range and average length of periods. 
 VERTICAL-TUBE EXPERIMENTS. 
 
 Date ticks were 
 collected. 
 
 Number 
 of ticks. 
 
 Range of 
 periods. 
 
 A verage 
 of periods. 
 
 Date ticks were 
 collected. 
 
 Number 
 of ticks. 
 
 Range of 
 periods. 
 
 Average 
 of periods. 
 
 1907. 
 June 1 
 
 7 
 
 Days. 
 tj to 9 
 
 Days. 
 1 
 
 1908. 
 Jan. 1 29 and 30... 
 
 
 Days. 
 34 to 1)3 
 
 Day*. 
 41.2 
 
 July 1 
 
 7 
 
 3 to 4 
 
 3.9 
 
 Feb. 3, 4, 27, and 28. 
 
 
 8 to 30 
 
 22.2 
 
 \ug. 1 and 31 
 
 14 
 
 2 to 4 
 
 3.1 
 
 Mar. 20 and 29. ... 
 
 9 
 
 4 to 8 
 
 5.2 
 
 Oct 1 
 
 7 
 
 4 to ti 
 
 4 3 
 
 Apr. 29 
 
 14 
 
 4 to 7 
 
 5 9 
 
 Nov. 1 and 30. 
 Dec. 29 
 
 11 
 3 
 
 7 to 9S 
 39 to 03 
 
 30.5 
 49.3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 HORIZONTAL-TUBE EXPERIMENTS. 
 
 1907. 
 Aug 31 
 
 4 
 
 3 
 
 3 
 
 1908. 
 Feb. 3, 24,27,and28. 
 
 , 
 
 10 to 33 
 
 18.3 
 
 Oct 1 
 
 4 
 
 4 
 
 
 Mar. 1, 3, 23, and 25. 
 
 7 
 
 5 to 11 
 
 7 
 
 Nov. 1 and 26 
 
 5 
 
 9 to 33 
 
 18.2 
 
 Apr. 29 and 30. 
 
 10 
 
 5 to 8 
 
 6.5 
 
 Dec 25 
 
 2 
 
 27 to 33 
 
 30 
 
 May 1 
 
 
 
 5 to 9 
 
 C.I 
 
 
 
 
 
 
 
 
 
 In both tables it is seen that the highest average is for the mont h 
 of December and the lowest for the month of August. 
 
 THE OVIPOSITIOX PERIOD. 
 
 The duration of this period depends on the temperature, and to a 
 less degree on a number of other things, such as state of engorgement, 
 number of eggs laid, etc. The ticks used were always good specimens, 
 as near complete engorgement as it was practicable to obtain. The 
 average oviposition period for different months of the year, as shown 
 in the following table, ranged from 8.3 days for June, 1907, to 127.5 
 days for November of the same year. The maximum period noted was 
 152 days and the minimum 3 days, observed in the case of ticks 
 which began ovipositing in November and June, respectively.
 
 14 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 Oviposition period Range and average length of periods. 
 VERTICAL-TUBE EXPERIMENTS. 
 
 Month oviposition 
 began. 
 
 Number 
 of ticks. 
 
 Range of 
 periods. 
 
 Average 
 of periods. 
 
 Month oviposition 
 began. 
 
 Number 
 of ticks. 
 
 Range of 
 periods. 
 
 Average 
 of periods. 
 
 1907. 
 June 
 
 
 Days. 
 3 to 14 
 
 Days. 
 8 3 
 
 1908. 
 January 
 
 2 
 
 Days. 
 54 to 87 
 
 Days. 
 70 5 
 
 July 
 
 
 4 to 20 
 
 12 9 
 
 
 3 
 
 37 to 63 
 
 46 7 
 
 August 
 
 
 12 to 19 
 
 15.6 
 
 March 
 
 14 
 
 17 to 43 
 
 30 2 
 
 September 
 
 
 14 to 19 
 
 16.5 
 
 April 
 
 7 
 
 14 to 35 
 
 24 9 
 
 October 
 
 
 21 to 37 
 
 32 9 
 
 Mav 
 
 14 
 
 19 to 27 
 
 22 8 
 
 November 
 
 
 78 to 151 
 
 98.4 
 
 
 
 
 
 
 
 
 
 
 
 
 
 HORIZONTAL-TUBE EXPERIMENTS. 
 
 1907. 
 September 
 
 (j 
 
 9 to 21 
 
 15 
 
 1908. 
 January 
 
 4 
 
 73 to 91 
 
 79 
 
 October .... 
 
 4 
 
 22 to 37 
 
 29.7 
 
 March 
 
 16 
 
 26 to 49 
 
 34.6 
 
 November 
 
 4 
 
 83 to 152 
 
 127.5 
 
 April 
 
 1 
 
 24 
 
 24 
 
 
 
 
 
 Mav 
 
 16 
 
 15 to 24 
 
 20.8 
 
 
 
 
 
 
 
 
 
 INCUBATION PERIOD. 
 
 The duration of this period depends principally on the temperature. 
 It was found to range from 19 days in the summer to 180 days begin- 
 ning in the fall. Low temperatures not only retard but even may 
 arrest temporarily or permanently the development of the eggs. 
 Moisture, although necessary to development, has but a small influ- 
 ence, if any, on the rate at which this takes place. 
 
 The conditions essential to the development and eventual hatch- 
 ing of eggs are a proper supply of moisture and a favorable tempera- 
 ture. All that is required in the way of moisture is a sufficient 
 atmospheric humidity to prevent eggs losing moisture by evaporation. 
 With regard to temperature it may be said that the maximum, mini- 
 mum, and optimum temperatures for development of the eggs have 
 not been determined. Hunter and Hooker 12 (1907) have assumed 
 43 F. as the minimum, but this has not yet been verified by experi- 
 ment. Eggs are frequently killed by the low temperatures occurring 
 during the winter months, although those that have been incubated 
 for a time are less susceptible to the ill effects of cold than those newly 
 laid. 
 
 As has been previously stated, the eggs were removed from each 
 female tick at the end of every 24 hours and placed in vertical tubes. 
 A record was kept of the date each lot was laid, the date the eggs 
 began to hatch, and the date they completed hatching. The latter 
 date is, however, only approximately correct, since it is not possible 
 to determine accurately when all the eggs of a lot have hatched, on 
 account of the fact that some eggs having all the marks of viability 
 frequently fail to hatch. By using the three dates just mentioned, 
 two incubation periods were determined for each lot of eggs, which
 
 THE HATCHING PERIOD. 
 
 15 
 
 are referred to here as the maximum and minimum. The range of 
 the incubation periods of the eggs laid by each tick is given in Table 1 
 of the Appendix. The range of the minimum incubation periods and 
 the averages for each month, from June, 1907, to May, 1908, are given 
 in the following table: 
 
 Incubation period Range and average length of minimum incubation periods. 
 
 Month eggs 
 deposited. 
 
 Number 
 of lots. 
 
 Range of 
 periods. 
 
 Average 
 of periods. 
 
 Month eggs 
 deposited. 
 
 Number 
 oflots. 
 
 Range of 
 periods. 
 
 Average 
 of periods. 
 
 1907. 
 June 
 
 60 
 
 Days. 
 22 to 27 
 
 Days. 
 24.5 
 
 1908. 
 February 
 
 1 
 
 Days. 
 80 
 
 Days. 
 
 80 
 
 July 
 
 82 
 
 19 to 24 
 
 20.5 
 
 March 
 
 270 
 
 46 to 63 
 
 52.7 
 
 August 
 
 90 
 
 19 to 24 
 
 21.2 
 
 April 
 
 197 
 
 36 to 53 
 
 43.6 
 
 September 
 
 81 
 
 28 to 64 
 
 35.9 
 
 May 
 
 279 
 
 23 to 34 
 
 26.3 
 
 October 
 
 145 
 
 165 to 180 
 
 173.1 
 
 
 
 
 
 November 
 
 31 
 
 148 to 170 
 
 155.5 
 
 
 
 
 
 December 
 
 7 
 
 117 to 139 
 
 128. 6 
 
 
 
 
 
 
 
 
 
 
 
 
 
 From the above table it is seen the averages increase from July to 
 October, 1907, and decrease from November, 1907, to May, 1908. The 
 average for June, 1907, being higher than for July, which marks the 
 beginning of the increase, indicates that the average for the latter 
 month is the lowest that would have been obtained had the experi- 
 ments covered the first part of the year. The longest minimum 
 incubation period was 180 days and the shortest 19 days. 
 
 HATCHING PERIOD. 
 
 The eggs deposited by a female do not all hatch at the same time, 
 but approximately in the sequence in which they are laid. The time 
 required for all of the eggs to hatch after hatching begins may be 
 called the hatching period. This may be considered normal in 
 length only when approximately ah 1 the eggs hatch or a goodly 
 portion of the first and the last eggs deposited hatch. Because of 
 the low percentage of eggs which hatched in the case of some of the 
 ticks the hatching periods of these have no significance and are, 
 therefore, not considered in the following table. The average period 
 for different months of the year is seen in the following table to range 
 from 10.6 days for July, 1907, to 36 days for October of the same 
 year. The maximum period observed was 49 days and the minimum 
 4 days. The eggs of all the ticks collected previous to October, 1907, 
 hatched in the fall and those laid by ticks collected October 1 did not 
 begin to hatch until the following March, and of course the eggs of 
 those collected during November and the succeeding months did not 
 begin to hatch until later, consequently no hatching periods were 
 obtained during the colder part of the year. It is therefore evident 
 that the maximum period observed is much less than might occur 
 with a slightly different winter season, or if ticks had been collected 
 89053 Bull. 13011 3
 
 16 
 
 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 on such a date that the hatching of the eggs would have begun in 
 the fall and not been completed until the following spring. 
 
 Hatching period Range and average length of periods. 
 
 VERTICAL-TUBE EXPERIMENTS. 
 
 Month hatching 
 began. 
 
 Number 
 of ticks. 
 
 Range of 
 periods. 
 
 Average 
 of periods. 
 
 Month hatching 
 began. 
 
 Number 
 of ticks. 
 
 Range of 
 periods. 
 
 Average 
 ofperiods. 
 
 1907. 
 July 
 
 14 
 
 Days. 
 4 to 17 
 
 Days. 
 10 6 
 
 1908. 
 March 
 
 6 
 
 Days. 
 21 to 31 
 
 Days. 
 26 
 
 August 
 
 7 
 
 8 to 16 
 
 13.4 
 
 April 
 
 8 
 
 16 to 27 
 
 23.6 
 
 October 
 
 6 
 
 31 to 49 
 
 36 
 
 May 
 
 11 
 
 12 to 18 
 
 14 3 
 
 
 
 
 
 June. 
 
 14 
 
 12 to 22 
 
 17 2 
 
 
 
 
 
 
 
 
 
 HORIZONTAL-TUBE EXPERIMENTS. 
 
 1907. 
 October 
 
 5 
 
 18 to 37 
 
 23.6 
 
 1908. 
 March 
 
 31 21 to 24 
 
 22 3 
 
 
 
 
 
 April 
 
 7 i 10 to 27 
 
 21.3 
 
 
 
 
 
 May... 
 
 12 ' 9 to 21 
 
 15.6 
 
 
 
 
 
 June 
 
 16 j 5 to 18 
 
 11.4 
 
 
 
 
 
 
 
 
 LONGEVITY PERIOD. 
 
 The longevity of the larvae depends on individual vitality, humid- 
 ity, and temperature. Some larvae do not have sufficient vitality to 
 disengage themselves from the ruptured eggshell and die partly inclosed 
 within it. This was especially noticeable in eggs laid during the 
 winter, so it would seem that a low temperature may affect the 
 vitality of unhatched larvae. Other larvae die very soon after 
 emerging. Cold prolongs longevity because of the fact that the 
 tick remains quiescent, and as a result the body fluids and nourish- 
 ment are conserved. A high relative humidity prolongs longevity 
 by hindering the loss of body moisture by evaporation and also by 
 causing the ticks to remain more quiescent than when the air is 
 dry. In addition to these factors certain instincts of the larvae 
 promote longevity. They respond negatively to light. In sunny 
 places they collect on the under or the shady side of leaves, stems, 
 and other objects, thus protecting themselves from the direct heat 
 of the sun. They also manifest an interesting adaptation in being 
 able to detect the presence of a possible host at a distance of 
 several feet. This fact was observed and verified many times with 
 larvae located on plots outdoors. Larvae that were quiescent when 
 one approached within 3 or 4 feet of a plot, in the course of a 
 half to several minutes became very active and extended their front 
 legs upward in a divergent position, waving them violently in an 
 evident attempt to seize onto a host. This instinct is probably 
 dependent on an olfactory sense resident in the organ of Haller 
 located on the tarsi of the first pair of legs. It may possibly be
 
 THE LONGEVITY PERIOD. 
 
 17 
 
 connected with a thermal sense, but this hardly seems probable, 
 since the reaction was found to occur just as readily on extremely 
 warm days as on cool days. The response takes place more quickly 
 when one is located on the windward side of the larvae. .This instinct 
 permits the larvae to remain quiescent without reducing their chances 
 for reaching a host. The periods of inactivity conserve the vitality 
 of the tick and consequently must prolong longevity. 
 
 In making observations on the longevity > the date when the larvae 
 in each tube began to die and when all of them were dead was re- 
 corded. In determining the longevity of the larvae resulting from 
 each lot of eggs, the date when the eggs began to hatch, together with 
 the two dates just mentioned above, were used, thus obtaining a min- 
 imum and maximum longevity period. 
 
 The range of the maximum and the minimum longevity and the 
 average of the former for lots of larvae hatched during the different 
 months of the year, are given in the following table: 
 
 Longevity period Range of maximum and minimum longevity and average of maximum 
 
 longevity. 
 
 
 
 Range of 
 
 Range of 
 
 Average 
 
 
 
 Range of Range of 
 
 Average 
 
 Month 
 hatched. 
 
 Num- 
 ber of 
 lots. 
 
 mini- 
 mum lon- 
 gevity 
 
 maxi- 
 mum lon- 
 gevity 
 
 of maxi- 
 mum lon- 
 gevity 
 
 Month 
 hatched. 
 
 Num- mini- 
 ber of mum Ion- 
 lots, gevity 
 
 maxi- 
 mum lon- 
 gevity 
 
 of maxi- 
 mum lon- 
 gevity- 
 
 
 
 periods. 
 
 periods. 
 
 periods. 
 
 
 
 periods. 
 
 periods. 
 
 periods. 
 
 1907. 
 
 
 Days. 
 
 Days. 
 
 Days. 
 
 1908. 
 
 
 Days. 
 
 Days. 
 
 Days. 
 
 July 
 
 106 
 
 4 to 39 
 
 7 to 85 
 
 38.6 
 
 March 
 
 24 
 
 5 to 22 
 
 57 to 94 
 
 73.2 
 
 August 
 
 83 
 
 9 to 36 
 
 9 to 192 
 
 84.9 
 
 April 
 
 189 
 
 3 to 63 
 
 19 to 99 
 
 65.1 
 
 September . 
 
 44 
 
 4 to 35 
 
 9 to 190 
 
 56.2 
 
 May. 
 
 406 
 
 2 to 57 
 
 4 to 103 
 
 62.3 
 
 October 
 
 75 
 
 5 to 163 
 
 30 to 234 
 
 167.4 
 
 June 
 
 380 
 
 4 to 55 
 
 8 to 128 
 
 65.1 
 
 November... 
 
 5 
 
 21 to 70 
 
 33 to 135 
 
 85 
 
 
 
 
 
 
 The eggs which hatched during July, August, and September were 
 kept in tubes which were not supplied with water other than that 
 originally added to the sand. This may account for the rather low 
 averages for July and September. It is noted that the highest average 
 is for the lots hatched during the month of October, and this month 
 also gave the longest maximum period; the lowest average is for 
 July, which likewise gave the shortest maximum longevity period. 
 
 TOTAL TIME OF NON PARASITIC DEVELOPMENT. 
 
 The period of nonparasitic development is the time from the date 
 the female drops until all the resulting larvae are dead. It is of prime 
 importance from a practical standpoint, since it indicates the length of 
 time animals must be kept out of an infested pasture in order for it to 
 become tick free. A summary of the data on this period is given in 
 the table following.
 
 18 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 Total time from dropping of female until all resulting larvse are dead. 
 
 Date engorged 
 females were 
 collected. 
 
 Number 
 of en- 
 gorged, 
 females. 
 
 Range of 
 entire-time 
 periods. 
 
 Average 
 of pe- 
 riods. 
 
 Date engorged 
 females were 
 collected. 
 
 Number 
 of en- 
 gorged 
 females. 
 
 Range of 
 entire-time 
 periods. 
 
 Average 
 of pe- 
 riods. 
 
 Junel, 1907. ... 
 Julyl, 1907. ... 
 Aug. 1, 1907. .. 
 
 7 
 
 7 
 
 Days. 
 79 to 100 
 82 to 112 
 172 to 221 
 
 Days. 
 86.9 
 101 
 199.6 
 
 Dec. 29, 1907, to 
 Jan. 1,1908 
 Jan. 29 to Feb. 4, 
 
 3 
 
 Days. 
 181 to 207 
 
 Days. 
 196.3 
 
 Aug. 31, 1907 
 
 6 
 
 230 to 272 
 
 250.7 
 
 1908 
 
 7 
 
 156 to 189 
 
 173 1 
 
 Oct. 1, 1907. ... 
 Nov. 1, 1907. ... 
 Nov. 30, 1907 . . . 
 
 7 
 7 
 . 3 
 
 276 to 288 
 200 to 253 
 187 to 249 
 
 279.6 
 232.7 
 217 
 
 Feb. 27 to 28, 1908. 
 Mar. 26 to 29, 1908. 
 Apr. 29, 1908 
 
 2 
 9 
 
 14 
 
 143 to 162 
 144 to 161 
 122 to 173 
 
 152.1 
 152.1 
 142.8 
 
 In the above table the averages are seen to increase from 86.9 days 
 for June, to 279.6 days for October, 1907, and to decrease from the 
 latter month for the rest of the time. The maximum periods likewise 
 increased from 100 days for June to 288 days for October and there- 
 after steadily decreased each month until March. 
 
 NUMBER OF EGGS LAID AND PERCENTAGE HATCHED. 
 
 The eggs laid by each female (except in the case of controls, which 
 are referred to below) were counted when they were removed and 
 before the}' were placed in the incubation tubes. And furthermore, 
 after all the larvse in each tube had perished, the unhatched eggs 
 were removed and counted. The purpose of this was twofold, first to 
 determine the number of eggs laid by a female, and, second, to calcu- 
 late the percentage of eggs which hatched. In the case of certain ticks, 
 the eggs of which were left uncounted for the purpose of serving as 
 controls on the counted eggs, it was necessary, in addition to count- 
 ing the unhatched eggs, to count the dead larvse in order to determine 
 the number of eggs laid. The data obtained are given in columns 3 
 ;ind 11, respectively, of Table 1, Appendix. A summary showing the 
 range in the number of eggs laid by each lot of ticks, the average number 
 of eggs laid and per cent hatched, is presented in the following table: 
 
 Egg laying and hatching Total and average number of eggs laid and per cent hatched. 
 
 Date ticks col- 
 lected. 
 
 Num- 
 ber of 
 ticks. 
 
 Eggs laid. 
 
 Aver- 
 age 
 eggs 
 laid. 
 
 Eggs 
 hatched. 
 
 Date ticks col- 
 lected. 
 
 Num- 
 ber of 
 ticks. 
 
 Eggs laid. 
 
 Aver- 
 age 
 
 eggs 
 laid. 
 
 Eggs 
 hatched 
 
 June 1, 1907. . 
 July 1, 1907. . 
 Aug 1, 1907. . . 
 Aug31, 1907.. 
 Oct 1,1907.. . 
 Novl, 1907. . 
 Nov 30, 1907 . . 
 
 7 
 6 
 7 
 7 
 4 
 
 Number. 
 630-3,095 
 1.858-3,820 
 1,851-3.683 
 2.049-2,809 
 960-3,385 
 991-2,961 
 357-3, 20; 
 
 Number 
 1,811 
 2,919 
 2, WO 
 2,405 
 2,563 
 2,129 
 2,173 
 
 Per ct. 
 73-95 
 90-97 
 90-98 
 57 97 
 
 Dec. 29, 1907, to 
 Jan. 1,1908... 
 Jan 29, to Feb. 
 4, 1908 
 
 4 
 
 7 
 2 
 9 
 9 
 
 Number. 
 1,970-4,272 
 
 806-4.276 
 2,302-2,925 
 2.680-4,559 
 3, 246-5, 105 
 
 Number 
 3,149 
 
 3,331 
 
 2,614 
 3,507 
 4,089 
 
 Perct. 
 0-35 
 
 14-86 
 62-96 
 66-97 
 33-98 
 
 77-92 
 1-7 
 0-18 
 
 Feb. 27-28, 1908. 
 Mar. 26-29. 1908. 
 Apr. 29, 1908....
 
 EXPERIMENTS WITH HORIZONTAL, TUBES. 
 
 19 
 
 The minimum number of eggs laid was, as the above table indicates, 
 357, and the maximum number 5,105. The average number ranges 
 from 1,811 to 4,089. The percentage of eggs hatching in the case of 
 ticks collected from November 1, 1907, to January 1, 1908, ranged 
 from to 35, and for the rest of the time from 14 to 98. 
 
 In counting the eggs they were placed on white paper and arranged 
 in a long row one egg deep and several eggs wide. In order to injure 
 them as little as possible and reduce the chances of crushing them, 
 small spatulas made of thin paper were used in handling them. The 
 counting was done with the aid of a pocket lens. For the purpose of 
 determining whether the manipulation involved in counting the eggs 
 reduced the percentage that hatched, two ticks in each of the first six 
 sets of experiments were selected as controls, their eggs not being 
 counted. The results are given in the following table: 
 
 Percentage of eggs hatching from counted and uncounted lots. 
 
 Date ticks collected. 
 
 Num- 
 ber 
 of 
 ticks. 
 
 Eggs counted 
 or uncounted. 
 
 Per 
 
 cent 
 hatched. 
 
 Date ticks collected. 
 
 Num- 
 ber 
 of 
 ticks. 
 
 Eggs counted 
 or uncounted. 
 
 Per 
 
 cent 
 hatched. 
 
 1907. 
 June 1 
 
 5 
 
 Counted . . 
 
 92. 1 
 
 1907. 
 Aug. 31 
 
 6 
 
 Counted .... 
 
 79.5 
 
 Do ... 
 
 2 
 
 Uncounted. 
 
 84.9 
 
 Do 
 
 1 
 
 Uncounted.. 
 
 97 
 
 July 1 
 
 5 
 
 Counted 
 
 95.3 
 
 Oct. 1 
 
 
 Counted 
 
 85.5 
 
 Do... 
 
 2 
 
 Uncounted. 
 
 95 
 
 Do 
 
 2 
 
 Uncounted.. 
 
 85.7 
 
 Aug. 1 ... 
 
 5 
 
 Counted ... 
 
 95.3 
 
 Nov. 1 
 
 -5 
 
 Counted. . . 
 
 a4 
 
 Do 
 
 2 
 
 Uncounted. 
 
 95.8 
 
 Do 
 
 2 
 
 Uncounted.. 
 
 
 
 
 
 
 
 
 
 
 Two of the above averages for the controls are less and four are 
 more than the corresponding averages for the counted eggs. Disre- 
 garding, however, slight differences ranging from 0.2 to 1.6 per cent, 
 which have little significance, the corresponding average may be said 
 to be the same in all except two cases. In one of these the average 
 for the control is 17.5 per cent more and in the other 7.2 per cent less. 
 It seems safe to say from the above results that the manipulation 
 involved in counting, when done with moderate care, does not appre- 
 ciably lower the per cent of eggs hatching, and that this has not 
 materially affected the percentage of eggs hatched in the course of the 
 present experiments. 
 
 EXPERIMENTS WITH HORIZONTAL TUBES. 
 
 The tubes used in these experiments have already been described 
 on page 10 (see fig. 2). Those referred to below as being supplied 
 with moisture were either kept in a moist chamber or were of the 
 type having sand in one end. A summary of the data is given in the 
 table following.
 
 20 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 Summary of the data obtained from the experiments with horizontal tubes. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Total time 
 
 
 
 
 
 
 
 
 from date 
 
 Date ticks were 
 collected . 
 
 Preoviposi- 
 tion period. 
 
 Oviposi- 
 t i on period. 
 
 Incubation 
 period. 
 
 Hatching 
 period. 
 
 Longevity 
 of larvae. 
 
 Conditions 
 of 
 experiment. 
 
 females 
 were col- 
 lected to 
 
 
 
 
 
 
 
 
 death of 
 
 
 
 
 
 
 
 
 larvse. 
 
 1907. 
 
 Days. 
 
 Days. 
 
 Days. 
 
 Days. 
 
 Days. 
 
 
 Days. 
 
 AUK 31 
 
 3 
 
 9 to 17 
 
 30 to 31 
 
 18 to 22 
 
 a 195 to 217 
 
 Moisture 
 
 299 to 250 
 
 Oct. 1 
 
 4 
 
 22 to 37 
 
 165 to 167 
 
 21 to 24 
 
 78 to 92 
 
 do 
 
 247 to 261 
 
 Nov. 1 
 
 9 to 20 
 
 130 to 152 
 
 167 
 
 16 
 
 70 
 
 do 
 
 246 
 
 Nov. 26.. 
 
 20 to 33 
 
 (6) 
 
 
 
 
 do 
 
 
 Dec. 25 
 
 27 to 33 
 
 74 to 78 
 
 88 to 94 
 
 10 to 25 
 
 62 to 83 
 
 . do. . . 
 
 204 
 
 1908. 
 
 
 
 
 
 
 
 
 Feb. 3 
 
 29 to 33 
 
 35 to 49 
 
 53 to 59 
 
 20 to 27 
 
 87 to 109 
 
 do 
 
 172 to 194 
 
 Feb. 24 to Mar. 3.. 
 
 10 to 16 
 
 .50 to 40 
 
 50 to 56 
 
 16 to 24 
 
 71 to 105 
 
 ...do... 
 
 131 to 168 
 
 Mar. 23 to25 
 
 5 to 6 
 
 26 to 31 
 
 43 to 48 
 
 9 to 15 
 
 49 to 71 
 
 do. .. 
 
 103 to 121 
 
 Apr. 29 to 30.. 
 
 5 to 8 
 
 21 to 24 
 
 29 to 32 
 
 5 to 18 
 
 79 to 111 
 
 do 
 
 114 to 147 
 
 May 1 
 
 5 to 9 
 
 15 to 21 
 
 29 to 31 
 
 6 to 10 
 
 15 to 17 
 
 No moist- 
 
 50 to 53 
 
 
 
 
 
 
 
 ure. 
 
 
 o After all the eggs had hatched the larvae were placed on vegetation outdoors. 
 6 Only a few eggs were laid, all of which shriveled. 
 
 The minimum entire time when the tubes were kept moist occurred 
 hi the case of ticks collected March 23 to 25, 1908, and the maximum 
 with the ticks collected October 1, 1907. In the case of the vertical 
 tubes the maximum entire time also fell to the ticks collected October 
 1 . For the purpose of determining the influence of moisture on the 
 duration of the entire time some ticks collected May 1, 1908, were 
 kept in tubes which were not supplied with moisture. Other ticks 
 collected April 29 and 30 were supplied with moisture as usual. The 
 difference in the result is very striking, the duration in the latter 
 case being nearly three times as long as in the former. 
 
 RECORDS OBTAINED FROM THE FIELD PLOTS. 
 
 In the indoor experiments the conditions were made to correspond 
 as nearly as possible with those existing outside. It was evident, 
 however, even before the work presented in this bulletin was taken up, 
 that this could only be accomplished in a very imperfect manner and 
 that it would be well to conduct a parallel set of experiments outside 
 under natural conditions for the purpose of checking the indoor experi- 
 ments. Natural conditions are far from being uniform, however. 
 Even in the same pasture a variety of environments may be present 
 and the duration of the various periods in the life history of the tick 
 be quite different under each. Furthermore, climatic conditions may 
 vary considerably from year to year in the same place. The impor- 
 tant thing, however, from a practical standpoint is to determine the 
 environments that will give maximum and minimum periods. An 
 attempt was made to obtain such periods by running two sets of 
 field plots, one on well drained, sunny ground and the other on moist, 
 partly shady ground. The character of the plots and the method of
 
 INFLUENCE OF ENVIRONMENT. 
 
 21 
 
 confining the ticks have been described on page 11. In these experi- 
 ments it was not possible to make notes on individual ticks, and con- 
 sequently the data are not as complete as those of the indoor work. 
 The data of economic importance are the date the first eggs hatched 
 and the date all the larvae were dead. 
 
 In four of the plots located in the sun, started June 3, July 1, 
 August 1, and August 31, 1907, the engorged ticks were destroyed 
 by small red ants; in two started November 1, 1907, and January 31 
 to February 1, 1908, eggs were deposited but no larvae appeared; 
 and in three started November 26 and December 16, 1907, and 
 January 1, 1908, all the females died without ovipositing. In the 
 case of plots located under partly shady conditions, in three of them 
 started on August 31, October 1, and November 1, 1907, eggs were 
 deposited but no larvae appeared; in two started November 26 and 
 December 16, 1907, all the females died without depositing eggs. 
 
 In all the plot experiments started between November 1, 1907, and 
 January 1, 1908, inclusive (see second table below), no larvae appeared, 
 either for the reason that the females succumbed to the severe weather 
 or that the eggs deposited failed to hatch. 
 
 The records of the last three plots located in the sunlight and in 
 the shade furnish an interesting comparison with regard to the 
 influence of environment on the eggs and larvae. They are given in 
 the following table: 
 
 Influence of environment on eggs and larvae. 
 
 In sunlight 
 
 
 
 In shade. 
 
 
 
 Date ticks were collected. 
 
 Date first 
 eges 
 hatched 
 
 Date all 
 larvse 
 wore 
 dead. 
 
 Date ticks were collected. 
 
 Date first 
 eggs 
 hatched. 
 
 Date all 
 larvae 
 were 
 dead. 
 
 1908. 
 Mar. 1-2 
 
 May 8 
 
 July 31 
 
 1908. 
 Feb 28-29 
 
 Mav 18 
 
 Aug. 3 
 
 Mar. 27-28 
 
 Mav 20 
 
 Aug. 8 
 
 Mir. 27 
 
 June 8 
 
 Aug. 23 
 
 Apr. 27 
 
 June 5 
 
 July 28 
 
 Apr. 27 
 
 June 18 
 
 Sept. 5 
 
 
 
 
 
 
 
 Larvae appeared from 10 to 19 days earlier in the sunny plots than 
 in the shady ones and succumbed 3 to 39 days earlier. 
 
 a Specimens of this ant were sent to Prof. \V. M. Wheeler, of Harvard University, for identification, and 
 found to be one of our small "Thief ants,"* Solcnopsis m^lrfla Say, which is common in pastures and fields, 
 where it leads a subterranean life and feeds on larvae and pupas of other ants, on sprouting seeds, dead 
 insects, etc.
 
 22 
 
 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 In the following table a comparison is made of the results obtained 
 in the vertical tubes and in the field plots: 
 
 Comparison of records of vertical tubes and field plots, Auburn, Ala., 1907-8. 
 
 Vertical tubes. 
 
 Field plots. 
 
 Date females were collected. 
 
 Date first 
 eggs 
 hatched. 
 
 Date all 
 larvse 
 were 
 dead. 
 
 Date females were collected. 
 
 Date first 
 eggs 
 hatched. 
 
 Date all 
 larvae 
 were 
 dead. 
 
 June 1 1907 
 
 July 4 
 July 28 
 Aug. 27 
 Oct. 3 
 Mar. 19 
 Apr. 17 
 May 4 
 
 Apr. 28 
 Apr. 27 
 Apr. 28 
 May 19 
 June 4 
 
 Sept. 9 
 Oct. 21 
 Mar. 9 
 May 29 
 July 15 
 July 11 
 Aug. 5 
 
 July 23 
 Aug. 11 
 Aug. 7 
 Sept. 3 
 Oct. 19 
 
 June 4, 1907 
 
 July 7 
 July 29 
 Aug. 30 
 (a) 
 
 Aug. 29 
 Oct. 8 
 Mar. 27 
 
 July 1, 1907 
 
 July 1, 1907 
 
 Aug 1 1907 
 
 Aug. -1, 1907 
 
 Aug 31, 1907 
 
 Aug. 31, 1907 
 
 Oct. 1, 1907 
 
 Oct. 1, 1907 
 
 Apr. 10 
 (a) 
 
 ( 6 ) 
 () 
 W 
 May 14 
 May 8 
 May 20 
 June 5 
 
 June 8 
 
 Nov 1 1907 
 
 Nov. 1, 1907 ... 
 
 Nov. 30 1907 
 
 Nov. 26, 1907 
 
 
 Dec. 29, 1907 to Jan. 1, 1908 
 Jan 29 to Feb. 4, 1908 
 
 Dec 16 1907 
 
 
 Jan. 1, 1908 
 
 
 Feb. 1 and 2, 1908 
 
 July 22 
 Aug. 3 
 Aug. 23 
 Sept. 5 
 
 Feb 27 and 28 1908 
 
 Feb 28 to Mar 2, 1908 
 
 Mar. 26 to 29 1908 
 
 Mar 27 and 28, 1908 . . . 
 
 Apr. 29, 1908 
 
 Apr. 27, 1908 
 
 
 
 No larvae appeared. 
 
 & All died without ovipositing. 
 
 From the above table it will be noted that the period from the col- 
 lection of the ticks to the tune the first eggs hatched in the case of 
 the indoor experiments started June 1 and March 26-29 (33 and 54 
 days, respectively) is the same as for the corresponding outdoor ex- 
 periments. In the case of the remaining experiments the time is 
 shorter 1 to 22 days for the indoor than for the outdoor experiments. 
 In all the experiments, except the one begun August 1 , the time from 
 the collection of the ticks to the death of all the larvae was longer by 
 from 5 to 42 days in the indoor than in the corresponding outdoor 
 experiments. 
 
 PER CENT OF FEMALES OVIPOSITING. 
 
 The data obtained on this point are not very extensive. In each of 
 the lots of ticks collected on the dates indicated in the second column 
 of Table 1, Appendix, 100 per cent oviposited except in the case of 
 the ticks collected November 30 and December 29, 1907, to January 
 1, 1908, of which 80 and 33 per cent, respectively, oviposited. Tick 
 No. 27, collected August 31, 1907, deposited but 39 eggs, none of 
 which hatched. This tick was very probably abnormal, but the ticks 
 that failed to oviposit were no doubt unfavorably affected by low 
 temperature. 
 
 Of the ticks kept in the horizontal tubes only one failed to oviposit. 
 This was collected February 3, 1908. The majority of the engorged 
 females placed in the plots outside during the latter part of the fall 
 and the winter of 1907-8 failed to oviposit. They appeared to suc- 
 cumb as a result of low temperature and excessive moisture. The 
 first indication of abnormality usually noticed was a reddish tinge
 
 EFFECT OF IMMERSION IN WATER. 23 
 
 appearing over the Malpighian tubules, which normally appear as 
 yellow streaks through the integument o*f the tick. Then the tick 
 began to swell, becoming very tightly distended, tiie color became 
 dark, and finally, if not punctured by some enemy, the integument 
 ruptured of itself and a sanguineous fluid issued from the opening. 
 
 EFFECT OF IMMERSION IN WATER ON ENGORGED FEMALES. 
 
 A number of tests were carried out to determine what effect immer- 
 sion in water, both before and after the beginning of oviposition, has 
 on engorged females. On May 1, 1908, eight engorged females were 
 placed in separate wide-mouthed bottles and covered with distilled 
 water. All of them died without ovipositing. 
 
 The following tests were made in the Zoological Laboratory, 
 Washington, D. C. : 
 
 August 11, 1908, 10 engorged females were collected and placed in tap water. All 
 died without ovipositing. 
 
 August 13, 9 engorged females (collected August 12) were submerged in normal salt 
 solution. All died without ovipositing. 
 
 September 15, 13 engorged females (collected September 10) that had begun 
 to deposit eggs were submerged in tap water. None of them continued to deposit eggs. 
 
 September 15, 10 engorged females (collected September 10) that had begun to 
 oviposit were placed in a Petri dish and half covered with tap water. None of them 
 continued to deposit eggs. 
 
 September 21, 8 engorged females (collected September 15) that had begun to 
 oviposit were placed in tap water. All died without depositing additional eggs. 
 
 The first effect of water on engorged ticks is to cause them to 
 become distended, and later the coloring matter of the blood within 
 the body escapes and colors the water. In some instances the dis- 
 tention of the tick is so great that its form is almost spherical. This 
 was not so pronounced in normal salt solution as in tap water. 
 
 Hunter and Hooker 12 (1907) found that females submerged con- 
 tinuously in tap water failed to oviposit. In one experiment, how- 
 ever, they found that two out of five ticks submerged during October 
 for 91^ hours deposited viable eggs, but ticks submerged for 115J 
 hours failed to deposit eggs. 
 
 THE INFLUENCE OF MOISTURE ON THE INCUBATION PERIOD. 
 
 For the purpose of determining what influence moisture might have 
 on the duration of the incubation period, eggs were subjected to 
 different degrees of moisture. The eggs used each day had been 
 deposited by a number of females during the previous 24 hours. 
 Some of the lots were placed in the regular incubation tubes and others 
 in test tubes containing wet sand. In the former case the eggs rested 
 on cardboard that was never more than moist, while in the latter 
 case they rested directly on wet sand. In one instance, referred to
 
 24 
 
 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 below, the eggs of a tick (No. 138, Table 1) were floated on water. 
 This is considered a condition which will furnish a maximum amount 
 of moisture. 
 
 In determining the results of the tests the incubation periods of 
 lots of eggs deposited on the same date and kept in regular incuba- 
 tion tubes were averaged, and the same was done in the case of the 
 eggs placed on moist sand. The averages for lots deposited on 12 
 days during March, 1908, are as follows: 
 
 Average incubation periods of eggs under different moi:ture conditions. 
 
 
 Mar. 
 9. 
 
 Mar. 
 10. 
 
 Mar. 
 11. 
 
 Mar. 
 12. 
 
 Mar. 
 13. 
 
 Mar. 
 
 14. 
 
 Mar. 
 16. 
 
 Mar. 
 17. 
 
 Mar. 
 18. 
 
 Mar. 
 19. 
 
 Mar. 
 20. 
 
 Mar. 
 24. 
 
 On cardboard 
 
 Days. 
 55 
 
 Days. 
 53 
 
 Days. 
 54 
 
 Days. 
 53 
 
 Days. 
 53 
 
 Days. 
 52 
 
 Days. 
 51 
 
 Days. 
 51 
 
 Days. 
 53 
 
 Days. 
 53 
 
 Days. 
 53 
 
 Days. 
 51 
 
 On moist sand 
 
 51 
 
 52 
 
 3 
 
 52 
 
 51 
 
 50 
 
 50 
 
 49 
 
 53 
 
 51 
 
 55 
 
 51 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 It is seen that nine of the averages for eggs kept on moist sand run 
 from one to four days less, two are the same and one is two days more 
 than the corresponding averages for eggs on cardboard. The mean 
 average for the eggs on wet sand is approximately one day less than 
 for those on moist cardboard. 
 
 The averages for 169 lots of eggs placed in regular incubation tubes 
 and 101 lots placed on moist sand and on water (82 on moist sand and 
 19 on water), deposited from May 6 to 26, inclusive, 1908, show the 
 following result : Five of the averages for eggs on moist sand and on 
 water considered together are from one to two days less, thirteen are 
 the same, and three are one day more than the corresponding aver- 
 ages for eggs resting on cardboard. The average for all the lots of 
 eggs on moist sand and water is three-tenths of a day less than for 
 those on cardboard. 
 
 From these tests, so far as they go, it appears that an abundance of 
 moisture shortens the incubation period so little that for all practical 
 purposes its influence may be disregarded. 
 
 PERIODS IN THE PARASITIC PORTION OF DEVELOPMENT. 
 
 There are three stages in the parasitic portion of the development 
 of the tick, viz, larval, nymphal, and adult. Until the latter stage is 
 reached males and females are not recognizable with certainty. The 
 duration of each of these stages and the duration of a single infestation 
 upon cattle during different portions of the year are of great practical 
 importance. Upon the duration of an infestation depends the time 
 animals must be kept on tick-free fields in order to become free from 
 ticks. 
 
 Tick-free animals were infested at nine different times, as indicated 
 in column 1, Table 2, of the Appendix. It was found that the mini- 
 mum larval period ranged from 5 to 7 days; the minimum nymphal
 
 PERIODS IN PARASITIC DEVELOPMENT. 
 
 25 
 
 period of females, 9 to 11 days; the adult period, from a minimum of 
 5 to a maximum of 33 days. The duration of each infestation, as 
 given in the last column of the table, ranged from 30 to 66 days. The 
 lower temperature during the fall and winter retarded the second 
 molt of some of the ticks, prolonging the time that nymphs were 
 present, and increasing the duration of infestation. It seems pos- 
 sible also that the latter result may be partly due to delayed fertiliza- 
 tion of the females, which could readily obtain in case the atmospheric 
 temperature w r as such as to reduce the activity of the males. 
 
 The maximum numbers in column 9 of the table (length of nymphal 
 period) indicate the time from the molting of the first larva to the 
 molting of the last nymph, and consequently represent the time that 
 nymphs were present on the animal. This time in all probability is 
 much longer than the nymphal period of any individual tick. 
 
 A number of days previous to the second molt it is possible to dis- 
 tinguish male and female nymphs with a fair degree of certainty. 
 The former are somewhat smaller than the latter and also differ 
 slightly in color and shape. The first nymphs to molt are males. 
 The first female nymphs molt from one to several days later. All the 
 male nymphs molt before the last female molts if they originally 
 attached to their host on the same date. 
 
 In the infestations made on February 29, April 4, and May 23, after 
 the larvae had attached themselves a certain number were marked and 
 observed from day to day. The range of the periods observed in 
 these instances follow. 
 
 Lenyth of period*, and total duration of para'itic development. 
 
 Date larvae applied. 
 
 Sex. 
 
 Length of 
 larval 
 period. 
 
 Length of 
 nymphal 
 period. 
 
 Length of 
 adult 
 period. 
 
 Duration 
 of para- 
 sitic 
 period. 
 
 1908. 
 Feb. 29 
 
 Females... 
 Males . . 
 
 Days. 
 8 to 9 
 
 7 to J 
 7 to 1 
 
 Days. 
 10 to 15 
 S to 10 
 
 Da>/s. 
 5 to 13 
 
 Days. 
 25 to 34 
 
 Do 
 
 Do... 
 
 (?)... 
 
 
 A pr. 4 . . . 
 
 Females.. 
 Males . 
 
 (i to 
 5 to 8 
 
 9 to 14 
 Mo 12 
 9 to 12 
 8 to 13 
 
 4 to 9 
 
 25 to 20 
 
 Do 
 
 Mav 2:? 
 
 Fomalps. 
 
 (i O '.1 
 
 22 to 25 
 
 "Do 
 
 Males 
 
 
 
 
 Nineteen larva? were marked in the infestation of February 2<*. 
 One of theses died previous to the first molt, three disappeared after 
 the first molt, and one female died three days after the second molt. 
 The male located beneath the latter left on the following day. Twenty- 
 six larvae of the April infestation were marked. Sixteen of these 
 disappeared previous to the first molt, one after the first molt, and 
 one after the second molt. In the infestation of May 23, 23 larva 1 
 were marked. None disappeared previous to the first molt, four 
 disappeared after the first molt, none disappeared after the second 
 molt.
 
 . 
 
 26 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 There seems to be no satisfactory explanation for the disappearance 
 of the ticks, particularly those in the larval stage. Of course, ticks 
 shortly after the first and second molt could easily be rubbed off. In 
 comparing the maximum parasitic period in each of the three cases 
 given in the above table with the duration of the same infestations 
 given in Table 2, Appendix, it is noted that all the latter are longer. 
 The difference for the infestation made February 29 is 10 days; for 
 both April 4 and May 23, 12 days. The reason for tin's great differ- 
 ence is not clear. It may be due to one or several causes, such as 
 larva? remaining on the cattle for some days without attaching them- 
 selves (this has been noticed in several instances) or ticks after the 
 first and second molt not reattaching immediately or becoming 
 dislodged and later reaching the host again. 
 
 OBSERVATIONS ON THE MOVEMENT OF TICKS AFTER THE FIRST 
 
 AND SECOND MOLT. 
 
 Ransom 17 (1906, p. 5) pointed out the fact that Ifargaropus 
 annitfatus, though remaining on the host, must reattach itself after 
 the first and second molt just as other species do which drop from their 
 host and molt on the ground. Hunter and Hooker 12 (1907, p. 29) 
 state that repeated careful observations show that they do not actu- 
 ally detach themselves at either molt. As this question has a more 
 or less important bearing on the dissemination of ticks, and also, pos- 
 sibly, the transmission of Texas fever, as pointed out by Ransom " 
 (1906) , some observations were made along this line. Since the cuticle 
 shed at molting remains attached to the skin of the host for some time 
 thereafter, particularly following the second molt, it is an easy matter 
 to determine whether the rostrum of the tick is embedded at the origi- 
 nal point of attachment or elsewhere. The following observations 
 indicate that reattachnient may take place after both the first and 
 the second molt. Xot many specific observations were recorded with 
 regard to the movement of young females, but general observations 
 such as are recorded for August 7 were made at various times. The 
 nymphs referred to below were marked early in their larval stage by 
 clipping the hair surrounding them and were observed daily. 
 
 CHANGE OF LOCATION AFTER THE FIRST MOLT. 
 
 January 10, 1908, one newly molted nyuiph reattached 6 mm. from original point of 
 attachment of larva. 
 
 January 11. three newly molted nymphs reattached 3 to 6 mm. from original point. 
 
 May 28, one nymph just molted reattached 3 mm. from original point. 
 
 May 29, one nymph just molted reattached 8 mm. from original point. 
 
 May 29, two nymphs just molted reattached 2 mm. from original point. 
 
 May 29. four nymphs just molted reattached 4 mm. from original point. 
 
 May 30, two nymphs just molted reattached 2 mm. from original point. 
 
 May 30. six nymphs just molted reattached 4 mm. from original point.
 
 DISTINGUISHING MALE AND FEMALE NYMPHS. 27 
 
 CHANGE OF LOCATION AFTER SECOND MOLT. 
 
 On July 18, 1907, a cow was infested with larvae. August 7, all 
 the nymphs had molted. No females could be found that had wan- 
 dered any great distance. In many instances, however, females 
 were found located a fraction of a millimeter to 1 mm. posterior 
 and several millimeters to one side of the place where previously 
 attached. 
 
 In the case of a cow infested August 17, 1907, on September 4 a 
 newly molted female was observed attached 3 mm. to one side of its 
 nymphal skin. 
 
 In the case of a cow infested November 19, an unattached newly 
 molted female was observed December 19. She was in the hair just 
 above a male which was attached beneath a nymphal skin. On 
 December 20 the female was found attached near the male. 
 
 EARLY DISTINGUISHING OF FEMALE NYMPHS BY MALES. 
 
 Some interesting observations were made which show how early 
 the male tick may distinguish a nymph as a female and locate beneath 
 it. On November 19, 1907, a cow was infested with larvae. Novem- 
 ber 28, three males belonging to a previous infestation were found on 
 the right side of the dewlap, and on November 29 and December 2 
 two more were found, making five in all. On the latter date two of 
 them were located beneath nymphs, and on December 3 and 4 two more 
 located themselves beneath nymphs. December 5 the first male 
 nymphs of the new infestation molted. They \vere located on the 
 posterior part of the body. December 6 the male of the previous in- 
 festation that had not sought a nymph had disappeared and a male 
 was found beneath a nymph on the opposite side of the dewlap. 
 This was very likely the male of the previous infestation which had 
 disappeared from its former location, as none of the nymphs of the 
 new infestation had molted on this region of the body. The nymphs 
 selected by the five males molted from December 9 to 16 and proved 
 to be females. As observed in this case, therefore, female nymphs 
 were sought out by males 13 to 17 days after the former had been 
 placed on a cow as larvae, and 3 to 7 days or more before they molted 
 the second time. 
 
 EXPERIMENTS IN TRANSFERRING TICKS ON CATTLE. 
 
 The following experiments were undertaken for the purpose of 
 determining whether ticks which have accidentally dropped to the 
 ground after molting or have been dislodged in some manner will 
 reattach and develop, provided they reach a host. Ransom n (1906) 
 showed that ticks removed shortly after the first and second molt, 
 or just previous to the second molt, and permitted to molt in the
 
 28 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 laboratory will reattach themselves. Hunter and Hooker 12 (1907), 
 after repeated attempts, succeeded in getting two ticks to reattach 
 One was a female one-half engorged and the other an adult which 
 molted in the laboratory. The former remained attached six days 
 and then released its hold, although not fully engorged. It deposited 
 several hundred eggs, which failed to hatch. The failure to hatch was 
 not attributed to the reattachment of the tick. 
 
 Experiment No. 1. December 7, 1907, a female recently molted was removed and 
 placed on the dewlap. December 8, female had taken hold. December 13, female 
 was still present. No further record. 
 
 Experiment No. 2. December 8, a recently molted female was removed and placed 
 on the outside of the left ear. December 9, tick had disappeared. 
 
 Experiment No. 3. December 9, a female was removed and placed on the median 
 line between the shoulders. December 10, female had taken hold. A male was placed 
 with it. December 11, male had disappeared. December 13, a male had located 
 beneath the female. December 14, male had disappeared. December 17, female was 
 shriveled. 
 
 Experiment No. 4- December 14, removed a female one-sixth grown and placed it 
 on the median line between the shoulders. December 15, female had disappeared. 
 
 Experiment No. 5. January 22, 1908, removed four females recently molted and 
 placed them on the escutcheon of a cow free from ticks. January 23, two of the ticks 
 had attached themselves. The others had disappeared. January 25, one tick had 
 disappeared. February 14, 'the remaining tick dropped from host, but died without 
 depositing eggs. 
 
 Experiment No. 6. January 24, transferred two young females to a new host. 
 January 25, ticks had disappeared. 
 
 Experiment No. 7. January 27, transferred three females just molted to a cow. 
 They were removed as nymphs January 25 and molted January 27. They were placed 
 on the escutcheon and in about half an hour had apparently attached themselves. 
 January 28, ticks had disappeared. 
 
 Experiment No. 8. January 30, placed a female just molted on a cow. Female was 
 removed as a nymph January 25 and kept in the laboratory. Molted January 30. 
 January 31, tick still present. February 2, tick had disappeared. 
 
 Experiment No. 9. February 23, placed a female, which molted in the laboratory 
 February 22, on the escutcheon of a tick-free cow. February 24, female had dis- 
 appeared. 
 
 Experiment No. 10. February 26, placed two females, which molted in the labora- 
 tory February 24 and 25, on the escutcheon of a cow. At the end of 30 minutes they 
 had apparently attached themselves. February 27, ticks had disappeared. 
 
 Experiment No. 11. March 2, a female which was removed February 24 and molted 
 in the laboratory March 1 was placed on a cow. At the end of three hours it was 
 observed attached to the udder. March 4, tick had disappeared. 
 
 Experiment No. 12. March 5, placed two females on the dewlap of a cow. They 
 were removed as nymphs on February 24 and March 2 and molted in the laboratory 
 March 5. March 6, ticks had disappeared. 
 
 Experiment No. 13.- March 7, placed two females on the escutcheon of a cow. 
 They had been removed as nymphs March 2 and 4 and molted March 7. March 8, 
 ticks had disappeared. 
 
 Experiment No. 14. March 9, placed a female, which was removed as a nymph 
 March 2 and molted March 8, on the left shoulder of a cow. March 10, tick had dis- 
 appeared.
 
 BEARING UNFERTILIZED FEMALES. 29 
 
 Experiment No. 15. March 18, placed three females on the flank of a cow. They 
 had been removed as nymphs March 17 and molted March 18. They had disappeared 
 half an hour later, apparently having been licked off. 
 
 Experiment No. 16. March 19, three females, collected as nymphs March 17 and 
 molted March 19, were placed on the neck of a cow. March 20, one tick waa attached 
 to the shoulder, one to the dewlap, and the other had disappeared. March 21, the tick 
 on the shoulder had disappeared. March 29, tick was about one-third engorged. 
 April 1, tick was dead. 
 
 Experiment No. 17. March 26, placed a female, which was collected as a nymph 
 March 17 and molted March 26, on the neck of a cow. The tick disappeared the same 
 day. 
 
 Experiment No. 18. April 1, two females, which were collected as nymphs March 
 17 and molted March 31 and April 1, were placed on the neck of a cow. April 2, ticks 
 had disappeared. 
 
 Experiment No. 19. April 2, placed a female, which was collected as a nymph from a 
 horse and molted April 2, on neck of a cow. April 4, tick was present. April 5, tick 
 had disappeared. 
 
 In the above experiments 32 ticks, shortly after the second molt, 
 were applied with special care. Twenty-four of them disappeared 
 either on the same or the following day and 8 remained attached for 
 periods ranging from 2 to 23 days. The one that was attached for 
 23 days (Experiment No. 5) became nearly engorged and dropped, 
 but failed to deposit eggs. None of the remainder approached 
 engorgement. Two of them died attached to the host, while the rest 
 simply dropped off. 
 
 Unfortunately no tests were made with ticks in the stage just after 
 the first molt. It seems likely that ticks in this stage, on account of 
 their smaller size, would attach themselves with much greater facility 
 and develop to maturity more frequently than do adult females. 
 A female one-sixth grown, mentioned in Experiment No. 4, failed to 
 attach. 
 
 In addition to this test, on April 13, 1908, five females, which had 
 just been collected from a horse, ranging in size from just after the 
 second molt to one-sixth grown, were placed on a cow, but none of 
 them became attached. 
 
 EXPERIMENTS ON REARING UNFERTILIZED FEMALES. 
 
 It is next to impossible to arrange an experiment for rearing 
 unfertilized females that entirely excludes the possibility of error. 
 Perhaps the most reliable method would be to obtain an animal free 
 of all ticks and infest it with females that have molted in the 
 laboratory. Unfortunately all the experiments described in the 
 preceding section to rear females to engorgement by this method were 
 unsuccessful except in the case of one female transferred to a new host 
 shortly after molting (see Experiment No. 5, p. 28), which, however, 
 failed to deposit eggs. In some additional work attempted along 
 this line a different method was used. An animal free of ticks was
 
 30 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 infested with a small number of larvae. The male nymphs were 
 removed as soon as the sexes could be distinguished. The animal 
 was examined twice a day, but in spite of the greatest care some males 
 escaped and were occasionally found beneath females. In such cases 
 both were removed and destroyed. The females kept under obser- 
 vation were examined as a rule both morning and evening. It can 
 not definitely be asserted that they were unfertilized, since the method 
 used did not exclude this possibility, but at no time were males found 
 beneath them. The- results, while they prove nothing with regard 
 to undoubtedly unfertilized females, show at least two interesting 
 things which will be mentioned below. 
 
 April 19, 1908, a cow was infested with larvae. About one hundred were placed on 
 the right side of the neck and the same number on the inside of the left thigh. All the 
 nymphs that, so far as could be judged, were males were removed as soon as possible. 
 On May 12 a female with a male beneath her was removed. Both were destroyed. 
 May 22 a female dropped. It was not as large as an ordinary engorged female. 
 Length 8 mm., width 5 mm., very thin in the dorso- ventral axis, color yellow. This 
 tick began to oviposit May 27. The eggs developed white spots but failed to hatch. 
 On May 24 one female dropped but could not be found. On May 26 another female 
 dropped and was lost. No more ticks were collected from this animal. 
 
 A cow was infested May 27. Larvae were placed on the escutcheon and right side 
 of neck. Male nymphs were removed as soon as possible but some males escaped. 
 
 June 20, removed a fully engorged female beneath which a male was never seen. 
 Oviposition began June 24. Eggs hatched. 
 
 June 22, removed a fully engorged female beneath which a male was never seen. 
 Oviposition began June 24. Eggs hatched. 
 
 June 26, a fully engorged female dropped. A male was never observed with it. 
 Oviposition began June 29 and eggs hatched . 
 
 June 26-27, night, a female nearly engorged dropped. A male was never noticed 
 with her. Oviposition began June 29 and the eggs hatched . 
 
 June 29, removed two females nearly engorged; males were never seen with them. 
 Both oviposited and though the white urinary vesicle appeared in the. eggs not more 
 than half a dozen hatched. 
 
 July 18, removed a female two-thirds engorged. Eggs did not hatch. 
 
 July 24, removed the last two females. They were not fully engorged and had 
 grown very slowly. One died without ovipositing and the other laid a normal number 
 of eggs but these failed to hatch. 
 
 From the above observations it can be concluded that females 
 which at least have not had males with them for any length of time 
 (and possibly not at all) will as a rule deposit a normal number of 
 viable eggs. It should be mentioned that Morgan 13 (1899, p. 129) 
 records observations on a presumably unfertilized female which laid 
 viable eggs. Another thing indicated is that the parasitic period 
 may be prolonged by excluding males, and in consequence of this 
 the period that an animal remains infested is increased. In the case 
 of the animal infested May 27, the duration of the infestation was 58 
 days or about one and a half times as long as occurred in the case of 
 a cow infested May 23 of the same year. That the adult period is not
 
 THE OCCURRENCE OF DEAD TICKS. 31 
 
 always prolonged, however, is indicated by the experiment with a 
 newly molted female that was transferred to an animal January 22 
 and dropped February 14, after an adult period of 23 days (Experi- 
 ment No. 5, p. 28). This comes within the range (8 to 33 days) of 
 the adult period obtained at about the same time on another animal 
 (Table 2, Appendix) . The tick obtained from the cow infested April 
 19 remained on the cow 33 days and the one that dropped May 26, 
 37 days, which is 5 days and 1 day less, respectively, than the dura- 
 tion of an infestation of another animal made April 4. 
 
 THE OCCURRENCE OF DEAD TICKS ON CATTLE. 
 
 Dead ticks are frequently found attached to cattle. In some 
 instances, especially in the case of partially or fully engorged females, 
 they have clearly been crushed by the host rubbing or coming in 
 contact with fences, buildings, etc. In man}' instances, however, 
 dead ticks are found that have not been injured in this manner, and a 
 microscopical examination of a number of such ticks failed to reveal 
 a fungus or anything that might have caused death. 
 
 In observations made from November 6, 1907, to March. 26, 1908, 
 on animals used in the life-history studies, dead nymphs were noticed 
 most frequently, females next, and only one male and one larva were 
 found dead. The dead ticks did not occur uniformly over the entire 
 body. The greater number were foil ml on the neck and shoulders, 
 and then in the order named, on the tail, dewlap, vulva, and flank. 
 
 The following is a record of dead ticks found on cattle: 
 
 November 6, 1907, one nymph on tail. November 10, one nymph on tail. Decem- 
 ber 6, one nymph on side of neck. December 14, one nymph on side of neck. De- 
 cember 30, one nymph on dewlap. February 1, 1908, one nymph near vulva. Feb- 
 ruary 14, one nymph on neck. February 20, female one-sixth grown, on shoulder. 
 February 21, three nymphs on neck. February 22, one female on neck. February 23, 
 two nymphs on neck. February 26, female, nearly grown, at root of tail. February 
 27, two nymphs on neck. March 5, one larva on shoulder. March 17, one nymph on 
 neck. March 19, one nymph on shoulder. March 19, one male on neck. March 24, 
 one nymph on dewlap. March 25, a female attached near the edge of a pustule on the 
 right flank. March 26, female about one-third down on tail. She had a male beneath 
 her. 
 
 HOST RELATIONS OF THE CATTLE TICK. 
 
 Ixodes annulatus ( M. annulatus) was first reported by Say (1821) 
 from a deer (Cervus virginianusCariacus amcncanus] from east 
 Florida. There are specimens in the collection of the zoological 
 laboratory of this bureau collected from a deer in Santa Barbara 
 County, Cal., and at San Simeon, San Luis Obispo County, Cal. 
 Besides cattle, this tick occurs frequently on horses and mules running 
 on infested pastures. Hunter 11 (1907) reports the tick on sheep (Oris 
 aries) in Jackson, Calhoun, and Victoria Counties, Tex. During the 
 summer and fall of 1907, in the course of the work upon which the
 
 32 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 present paper is based the cattle tick was collected from sheep at 
 the Alabama Experiment Station, Auburn, and also in Wilcox County, 
 Ala. There are specimens in the zoological laboratory of this bureau 
 from a goat (Capra Tiircus) collected in Elmore County, Ala. 
 
 Ransom 17 (1906) in an account of an experimental infestation of 
 a cat reports ticks present in the larval and nymphal stage. Only 
 one nymph molted a female that never became engorged. Males 
 and females that molted in the laboratory attached themselves to 
 a tame rabbit, but the females failed to develop further. Din- 
 widdie 9 (1908) reared experimentally the cattle tick on a dog. The 
 females failed to reach the usual size but deposited viable eggs. 
 
 In the course of the investigations reported in the present paper 
 larvae were applied to the rabbit, cat, dog, and sheep. 
 
 INFESTATION EXPERIMENTS ON RABBITS. 
 
 Experiment No. 1. A white rabbit was infested July 25, 1907, with larvae hatched 
 June 28-July 13. July 26, one larva attached to ear; four or five found crawlin'g 
 about through the hair. July 27, five larvse found attached to body and ears. July 
 30. one of the larvae found on ear continues to develop; one on the body dead, having 
 developed very little. August 1, one larva in the act of molting. August 6, a nymph 
 found on ear. August 12, nymph on ear still present, but not developing. A male 
 nymph had molted. August 17, no ticks could be found. 
 
 Experiment No. 2. August 19, 1907, white rabbit infested with larvae hatched 
 June 28-July 13. August 20, many larvae found attached to the ears. August 26, 
 one larva found on tip of right ear. August 29, one nymph found on inside of the tip 
 of the right ear. September 4, nymph still present. September 9 and 16, no ticks 
 could be found. 
 
 Experiment No. 3. September 25, 1907, white rabbit infested with larvae, the 
 progeny of ticks collected August 16 from a horse. October 8. no ticks could be 
 found. 
 
 Experiment No. 4- December 12, 1907, placed two females recently molted on 
 a white rabbit. The rabbit was also infested with larvae. December 13, no ticks 
 present. December 14, placed two more females recently molted on the rabbit. 
 December 15, the two transplanted females have disappeared. December 19, 30, 
 and January 17, 1908, no ticks present. 
 
 Experiment No. 5. January 20, 1908, a black and white rabbit infested with larvae. 
 Examinations made January 22. 30, and February 11 revealed no ticks. 
 
 Experiment No. 6. March 2, 1908, a black and white rabbit infested with larvae. 
 March 4, three dead larvae on the ears two attached and one in the hair. Two live 
 larvae seen crawling over the hair of the head and face. March 13, two dead larvae 
 noted. Neither showed any development. March 27, no ticks present. 
 
 Experiment No. 7. June 18, 1908, white rabbit infested with larvae. July 2, four 
 nymphs and a female just molted located on the ears. July 6, female had disappeared. 
 All the nymphs were dead. 
 
 Experiment No. 8. June 18, 1908, a white and gray rabbit was infested with larvae. 
 July 11, three dead nymphs were found on ears, one in stage of molting. A nymphal 
 skin was attached to the right ear. but the tick that had issued from it could not be 
 found. 
 
 It is evident from the above experiments that the rabbit is not 
 an appropriate host for the cattle tick. Out of a large number of
 
 HOST RELATIONS OF THE CATTLE TICK. 33 
 
 larvae placed on each rabbit none in sonic cases, in others compara- 
 tively few, attached themselves. It also appears that adults either 
 resulting from nymphs dislodged from cattle, or themselves dislodged 
 from cattle, would not be likely to attach to a rabbit in case an 
 opportunity were presented. 
 
 Larvae, nymphs, and adults (males and females) were reared on 
 rabbits, but in no case did females develop beyond the second molt. 
 The blood of the rabbit, or something else peculiar to the animal, 
 is unfavorable to the tick. This is evidenced by the fact that many 
 of the larvae and nymphs die without reaching the point of molting. 
 It seems possible, however, that in rare cases females might attain 
 partial or complete engorgement on rabbits, but the chances against 
 the tick on the rabbit are so great that such a possibility seems 
 negligible for all practical purposes. 
 
 In the above experiments only tame rabbits were used. An 
 attempt was made to raise a wild rabbit in captivity for use in the 
 experiments, but this was unsuccessful. A number of wild rabbits 
 obtained in the vicinity of Auburn, Ala., and in Wilcox County, 
 Ala., were examined for cattle ticks with negative results. Farmers 
 and stockmen in the South frequently state that they have found 
 cattle ticks on wild rabbits, but observation and experiment tend 
 to show that these must be other species of ticks, probably most 
 commonly Ilxmaphysalls leporis-palustris. 
 
 INFESTATION EXPERIMENTS ON A CAT. 
 
 Experiment No. 9. July 24, 1907, a kitten was infested with larvae hatched June 
 28-July 13. July 25, one larva was found attached to the inside of thigh. July 26, 
 larva on thigh still present and another located on left ear. July 29, larvae still present. 
 July 31, larva on thigh molted. August 6. nymph still present. August 10, nymph 
 disappeared. August 17, no ticks found. 
 
 Experiment No. 10. August 19. kitten infested with larvae hatched June 28-July 13. 
 August 20, a few larvae attached to the ears and abdomen. Examinations on August 
 26, 30, and September 4 revealed no ticks. 
 
 Experiment No. 11. A third infestation of the kitten was made December 12 without 
 result. 
 
 It appears so far as the above experiments go that the cat is even 
 a less favorable host than the rabbit. 
 
 INFESTATION EXPERIMENT ON A DOG. 
 
 Experiment No. 12. A dog was infested August 30, 1907, without result. 
 
 INFESTATION EXPERIMENTS ON SHEEP. 
 
 Seven attempts were made at various times to infest sheep with the 
 tick, and six of these were unsuccessful. In the case of one of the 
 unsuccessful attempts, made May 15, 1908, the animal was shorn on 
 
 a In July, 1910, 20 cottontails and 6 jack rabbits were shot on the Rincon Ranch. Gregory . Tex., and 
 examined for cattle ticks, with negative results. The rabbit tick (Ilsrmaphyaalis leporis-palu.*/ris) was 
 found on both jacks and cottontails, but was much more abundant on the former.
 
 34 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 the previous day to allow the larvae to reach the skin with greater ease. 
 In another, made September 25, the progeny of females matured on a 
 horse were used. 
 
 The record of the one infestation that was partially successful is as 
 follows : 
 
 July 24, 1907, a sheep was infested with larvae hatched June 28-July 13. July 27, 
 several larvae were attached to the ventral surface of the body. August 10, one female 
 tick a little over one-fourth grown was located on theoutside of the left ear. August 12, 
 tick had disappeared. There was a bloodstain where the tick had been attached, sug- 
 gesting that it may have been crushed. 
 
 In two of the negative experiments dead larvae were found in the 
 wool and also attached to the skin. At each infestation thousands of 
 larvae were applied, and, in most cases, to all parts of the body. The 
 very small number of larvae that attached themselves indicates that 
 sheep are not favorable hosts for the tick. The presence of dead 
 larvae seems to indicate that there are conditions on the surface of the 
 body or substances in the skin and blood unfavorable to the tick. 
 
 THE NATURAL OCCURRENCE OF THE CATTLE TICK ON SHEEP. 
 
 In order to determine to what extent, under natural conditions, 
 sheep serve as hosts for the cattle tick, some field experiments were 
 carried out, and in addition to this a considerable number of sheep 
 running on infested pastures were inspected. 
 
 In one of the field experiments six native sheep were allowed to run 
 with two cattle on an infested pasture containing about 4 acres, from 
 July 18, 1907, to November 6 of the same year. No ticks were found 
 at any time on the sheep, although the two cattle carried a moderate 
 infestation until shortly before the close of the experiment, when the 
 weather had become cool. 
 
 In a second experiment six native sheep were allowed to run alone 
 on an infested pasture similar to the above from July 18 to November 
 26, 1907. A ram and ewe were carefully examined on September 7. 
 The ewe was free of ticks and the ram had six ticks, as follows : One 
 engorged female, two males, and a dead female shortly after the sec- 
 ond molt, on the neck, one female about one-eighth grown on the 
 outside of the upper portion of one fore leg, and another female one- 
 sixth grown on the abdomen where hair was present. The engorged 
 female was unattached, but entangled in the wool in such a manner 
 that it could not drop from the host. It had been in this condition 
 for several days, as it had begun to oviposit. All of the sheep were 
 examined with great care on November 26, when the experiment was 
 closed, and were found free of ticks. 
 
 Through the kindness of Prof. D. T. Gray it was possible to inspect 
 sheep for cattle ticks at the experiment station at Auburn. The 
 sheep were running on an infested pasture, mostly woodland, along 
 with a few cattle.
 
 HOST RELATIONS OF THE CATTLE TICK. 35 
 
 On September 26, 1907, five sheep were subjected to a hand inspec- 
 tion and two were found infested. A native ewe had a female tick 
 on its ear; and a Dorset ram carried a number of males, females, and 
 one nymph. Some of the males were dead. They were unattached 
 and located in the wool. One female just after the second molt had 
 a male beneath her. The largest female collected was possibly a little 
 more than one-sixth grown. Most of the ticks were located on hairy 
 parts of the body, especially the legs. On one native ewe two dead 
 larvae were found. 
 
 On October 3, 12 native ewes and the Dorset ram in the above flock 
 were inspected. The ewes were free (one harbored a dead larva) and 
 the Dorset ram harbored two males. The skin of 7 of the ewes 
 was oily, that of the other 5 was moderately oily, and that of the 
 Dorset ram was not oily. On October 12 the ram was inspected 
 again. The wool and skin were very free from oil. Ticks were found 
 as follows: Two females one-third and one-sixth grown with males 
 beneath them on one hind leg a short distance above the hoof; a fe- 
 male just after the second molt on the posterior surface of the thigh 
 with a male situated some little distance below it; a female one- 
 fourth grown with a male, located on the scrotum; and a dead male in 
 the wool. On October 14 one of the females on the leg and the one on 
 the scrotum had become nearly engorged and were removed. The 
 former was crushed in removing. On October 16 another female 
 nearly engorged was removed from the hind leg. Both of the uninjured 
 ticks laid viable eggs. 
 
 On November 12 to 13, 1907, 36 sheep, principally grade South- 
 downs, in Wilcox County, Ala., were subjected to a careful hand 
 inspection. These sheep had been running continuously during the 
 summer and fall with 240 head of cattle that were grossly infested 
 with ticks prior to October 24, when they had been dipped. All the 
 sheep were in high flesh. All but one of them were free from ticks. 
 Thirteen of the sheep had wool that was not oily; 14 had moderately 
 oily wool; and S had oily wool. The one infested, a ram with 
 moderately oily wool, had a female tick one-half grown on the hairy 
 portion of the scrotum. 
 
 On November 14 to 18 a flock of 125 sheep in the same locality was 
 inspected. They had been running continuously during the summer 
 ami fall in a pasture of several hundred acres with over 200 cattle 
 which, at the time of the inspection, were grossly infested with ticks. 
 Three sheep, or about 2 per cent of the entire flock, were found in- 
 fested with live ticks. Dead ticks alone were found on 31 sheep, or 
 25 per cent of the flock. Rams were the hosts for the live ticks in all 
 three cases, and in the case of two of them the ticks were attached to 
 the scrotum. One ram had two ticks, a female just after the second 
 molt and another one-third engorged; another had but one tick, a
 
 36 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 female, newly molted, and the remaining one had a half-grown female 
 on the hairy portion of the leg. The wool of the first was moderately 
 oily and that of the other two not oily. 
 
 Dead ticks were found on 32 sheep. This includes one that also 
 had live ticks. Ticks in the larval stage were found on all these sheep, 
 and in addition one dead male was present in each of four instances. 
 The larvae were attached to the skin of the woolly regions of the body. 
 When they were removed a small scale of epidermis of the host was 
 brought way with the mouth parts, indicating that the larvae had 
 actually taken hold. The males were found unattached in the wool. 
 The condition of the wool of the entire flock was noted for the purpose 
 of determining, if possible, whether the amount of oil on the wool plays 
 any part in preventing ticks attaching to sheep. Eighty-six sheep, or 
 69 per cent, had wool not oily; 38 sheep, or 30 per cent, had wool 
 moderately oily; and 1 sheep, or about 1 per cent, had oily wool. 
 Twenty-seven per cent of the first class, 29 per cent of the second 
 class, and zero per cent of the third class of sheep carried ticks either 
 dead or alive. From this it would appear that the relative amount 
 of oil on the wool bears no important relation to the presence of ticks. 
 
 Summarizing the results of the observations on the natural infesta- 
 tion of sheep, it may be said that live ticks were found on the ears, 
 neck, legs, abdomen, and scrotum. In no case were they present in 
 great numbers. Rams seem to be much more favorable hosts than 
 ewes. Taking into account all the inspections made, ticks were found 
 on rams eight times and on ewes twice. In view of the large number 
 of ewes inspected as compared with the rams this result can not be 
 considered accidental. 
 
 THE PROGENY OF FEMALES MATURED ON SHEEP NONINFECTIOUS. 
 
 As previously stated, two of the female ticks that matured on sheep 
 laid viable eggs. One collected October 16, 1907, began to lay 
 October 23, 1907; hatching began April 9. and ended April 17, 1908. 
 The other, collected October 14, 1907, began to lay October 22 and 
 hatching began April 11, 1908. 
 
 On May 2, 1908, the larvae from the above ticks were placed on a 
 northern cow (No. 603) about 10 years old, at the Bureau of Animal 
 Industry Experiment Station, Bethesda, Md. Six hundred and 
 forty-three females matured, but the cow continued well and in 
 good condition, the temperature and number of erythrocytes remain- 
 ing normal. 
 
 On July 15, 1908, the progeny of ticks collected from the above 
 cow, May 28, 1908, were placed on two northern cattle, a bull (No. 
 585) and a heifer (No. 591), each about 1 year old. The temperature 
 of both animals remained normal.
 
 MAN AS A HOST OF THE TICK. 37 
 
 On September 14, 1908, and a number of times thereafter three 
 northern heifers (Xos. 582, 583, 584), each about 1J years old, were 
 infested with the progeny of ticks collected from bull No. 585, August 
 8, 1908, but none of them developed fever. 
 
 The above experiments show that the larvae were noninfectious, 
 but it is not known, of course, whether the two females of which 
 they were the progeny belonged to an infectious brood, and further- 
 more, if this were the case, it could not be known whether the two 
 females were infectious or not in their larval state, since it is fair to 
 assume that only a certain per cent of the progeny of infectious ticks 
 are infectious. Since, however, the particular sheep from which they 
 were collected ran on a pasture where infectious ticks undoubtedly 
 occurred and since ticks had been observed on this sheep a number of 
 times, the chances are, if the Texas-fever parasite could survive in the 
 blood of sheep, the blood of this one would have been infectious and 
 at least some of the progeny of the two females would have proved 
 infectious. 
 
 MAN AS A HOST OF THE TICK. 
 
 So far as known the cattle tick in its larval stage does not attack 
 man. Persons handling these larvae in the laboratory and passing 
 through fields infested with only cattle ticks are not attacked. Ran- 
 som 17 (1906) reports two experimental and one accidental attachment 
 of adults that molted in the laboratory. Below are records of the 
 attachment of ticks to man, obtained in the course of the present 
 investigations. 
 
 On June 18, 1907, 11.30 a. m., a female specimen of Margaropus 
 annulatus about one-third engorged was placed on the calf of the leg. 
 Shortly after noon it attached itself. It was removed June 19, 2.45 
 p. m., having drawn blood for more than 24 hours. At this time it- 
 had attained two-thirds of the usual size of an engorged tick. The 
 place where it was attached became highly inflamed, acquiring a 
 purplish color. 
 
 On August 13, 1907, a female that had molted in the laboratory 
 on August 7 was placed on the thigh. The tick attached itself, but 
 thereafter changed its location many times. It was present for 
 several days and then. disappeared. 
 
 On August 27 a nymph, shortly after the iirst molt, was placed on the 
 arm. It attached itself and remained so for several hours and then 
 disappeared, probably having been dislodged by the clothing.
 
 38 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
 BIBLIOGRAPHY. 
 
 The following list contains only works referred to in this bulletin: 
 
 1. COTTON, E. C. Tick eradication. The life history and habits of the North 
 
 American fever tick with special reference to eradication. Tennessee Agricul- 
 tural Experiment Station of University of Tennessee, Bulletin 81. Knox- 
 ville, 1908. 
 
 2. CURTICE, COOPER. The biology of the cattle tick. Journal of Comparative 
 
 Medicine and Verterinary Archives, vol. 12, No. 7, pp. 313-319. New York, 
 July, 1891. 
 
 3. About cattle ticks. Journal of Comparative Medicine and Veterinary 
 Archives, vol. 13, No. 1, pp. 1-7. New York, January, 1892. 
 
 4. The cattle tick (Boophilus boi'is Rileysp.). Texas Agricultural Experiment 
 Station, Bulletin 24. Bryan, 1892. 
 
 5. On the extermination of the cattle tick and the disease spread by it. Journal 
 of Comparative Medicine and Veterinary Archives, vol. 17, No. 9, pp. 649-655. 
 Philadelphia, September, 1896. 
 
 6. The cattle-tick plague, and what may be done to prevent it. Southern 
 Planter, vol. 58, No. 1, pp. 24-27. Richmond, January, 1897. 
 
 7. DALRYMPLE, W. H., MORGAN, H. A., and DODSON, W. R. Cattle tick and Texas 
 
 fever. Louisiana Agricultural Experiment Station, Bulletin 51, Second series. 
 Baton Rouge, 1898. 
 
 8. DINWIDDIE, R. R. Animal parasitism. Some Texas fever experiments, Arkan- 
 
 sas Agricultural Experiment Station, Bulletin 20. Little Rock, 1892. 
 
 9. Notes on the cattle tick and the tick fever of cattle. Arkansas Agricultural 
 Experiment Station, Bulletin 101. Fayetteville, 1908. 
 
 10. GRAYBILL, H. \V. Methods of exterminating the Texas-fever tick. United States 
 
 Department of Agriculture, Farmers' Bulletin 378. Washington, 1909. 
 
 11. HUNTER, W. D. Note on the occurrence of the North American fever tick on 
 
 sheep. United States Department of Agriculture, Bureau of Entomology, 
 Circular 91. Washington, 1907. 
 
 12. HUNTER, W. D., and HOOKER, W. A. Information concerning the North Ameri- 
 
 can fever tick, with notes on other species. United States Department of 
 Agriculture, Bureau of Entomology, Bulletin 72. Washington, 1907. 
 
 13. MORGAN, H. A. Ticks and Texas fever. Louisiana Agricultural Experiment 
 
 Station, Bulletin 56, second series. Baton Rouge, 1899. 
 
 14. The cattle-tick situation. Proceedings of the Society for Promotion of 
 Agricultural Science, Twenty-fourth Annual Meeting, pp. 72-74. Washing- 
 ton, 1903. 
 
 15. The Texas fever cattle-tick situation and the eradication of the tick by a 
 pasture rotation system. Louisiana Agricultural Experiment Station, Bulletin 
 82, second series. Baton Rouge, 1905. 
 
 16. NEWELL, WILMON, and DOUGHERTY, M. S. The cattle tick (Boophilus annulatus). 
 
 Studies of the egg and seed-tick stages. A simple method of eradicating the 
 tick. Louisiana State Crop Pest Commission, Circular 10. Baton Rouge, 1906. 
 
 17. RANSOM, B. H. Some unusual host relations of the Texas-fever tick. United 
 
 States Department of Agriculture, Bureau of Animal Industry, Circular 98. 
 Washington, 1906. 
 
 18. SCHROEDER, E. C. A note on the vitality of the southern cattle tick. United 
 
 States Department of Agriculture, Bureau of Animal Industry, Sixteenth 
 Annual Report, 1899, pp. 41-42. Washington, 1900.
 
 BIBLIOGRAPHY. 39 
 
 19. SCHKOEDER, E. C. Notes on the cattle tick and Texas fever. United States 
 
 Department of Agriculture, Bureau of Animal Industry, Twenty-second 
 Annual Report, 1905, pp. 49-70. Washington, 1907. 
 
 20. SCHROEDER, E. C., and COTTON, W. E. The growing of noninfected ticks and 
 
 afterwards infecting them. United States Department of Agriculture, Bureau 
 of Animal Industry, Sixteenth Annual Report, 1899, pp. 33-41. Washington, 
 1900. 
 
 21. The persistence of the Texas-fever organism in the blood of southern cattle. 
 United States Department of Agriculture, Bureau of Animal Industry, Twenty 
 second Annual Report, 1905, pp. 71-78. Washington, 1907. 
 
 22. SMITH, THEOBALD, and KJLBORNE, F. L. Investigations into the nature, causa- 
 
 tion, and prevention of Texas or southern cattle fever. United States Depart- 
 ment of Agriculture, Bureau of Animal industry, Bulletin 1. Washington, 1893.
 
 APPENDIX. 
 
 TABLE 1. Individual records of ticks used in experiments. 
 
 Num- 
 ber of 
 tick. 
 
 Date col- 
 lected. 
 
 Number 
 of eggs de- 
 posited. 
 
 Preovi- 
 position 
 period. 
 
 Ovi- 
 position 
 period. 
 
 Incuba- 
 tion pe- 
 riod. 
 
 Hatch- 
 ing pe- 
 riod. 
 
 Mini- 
 mum 
 longev- 
 ity. 
 
 Maxi- 
 mum 
 longev- 
 ity. 
 
 Entire 
 time. 
 
 Per cent 
 hatched. 
 
 I... 
 
 2 
 
 1907 
 June 1 
 do. 
 
 630 
 
 2,276 
 
 Days. 
 
 Days. 
 4 
 10 
 
 Days. 
 24 to 32 
 24 to 31 
 
 Days^ 
 11 
 
 Days. 
 13 
 9 
 
 Days. 
 50 
 46 
 
 Days. 
 83 
 79 
 
 86 
 94 
 
 3. 
 
 do. . 
 
 877 
 
 7 
 
 5 
 
 24 to 32 
 
 
 5 
 
 52 
 
 85 
 
 x 93 
 
 4 
 
 ..do.... 
 
 3,095 
 
 6 
 
 13 
 
 23 to 31 
 
 12 
 
 4 
 
 48 
 
 83 
 
 91 
 
 5 
 
 do 
 
 1,036 
 
 7 
 
 3 
 
 25 to 34 
 
 11 
 
 15 
 
 54 
 
 88 
 
 93 
 
 6 a... 
 
 do . 
 
 2,150 
 
 9 
 
 9 
 
 23 to 31 
 
 10 
 
 7 
 
 65 
 
 100 
 
 73 
 
 7 a... 
 
 . do 
 
 2,614 
 
 6 
 
 14 
 
 22 to 33 
 
 10 
 
 3 
 
 55 
 
 90 
 
 95 
 
 8 
 9. 
 
 July 1 
 .do... . 
 
 3,000 
 3,562 
 
 4 
 
 4 
 
 17 
 18 
 
 20 to 25 
 20 to 25 
 
 11 
 
 17 
 
 22 
 16 
 
 ' 82 
 62 
 
 112 
 91 
 
 % 
 96 
 
 10... 
 
 ...do.... 
 
 1,863 
 
 4 
 
 5 
 
 20 to 27 
 
 9 
 
 20 
 
 85 
 
 112 
 
 97 
 
 11. 
 
 do 
 
 3,515 
 
 4 
 
 20 
 
 19 to 25 
 
 15 
 
 16 
 
 
 103 
 
 95 
 
 12 
 13a.... 
 
 ...do. .. 
 ...do.... 
 
 1,858 
 3,820 
 
 4 
 
 4 
 
 4 
 16 
 
 20 to 25 
 19 to 25 
 
 4 
 15 
 
 24 
 20 
 
 55 
 
 67 
 
 82 
 98 
 
 90 
 
 94 
 
 14<J 
 
 do 
 
 2,814 
 
 3 
 
 10 
 
 20 to 25 
 
 9 
 
 19 
 
 79 
 
 109 
 
 % 
 
 15 
 
 16 
 
 Aug. 1 
 . .do 
 
 3,683 
 2,972 
 
 3 
 3 
 
 15 
 18' 
 
 20 to 25 
 20 to 24 
 
 8 
 15 
 
 22 
 10 
 
 160 
 
 187 
 
 187 
 218 
 
 90 
 96 
 
 17 
 
 do 
 
 2,536 
 
 3 
 
 15 
 
 20 to 25 
 
 15 
 
 4 
 
 15'-> 
 
 180 
 
 97 
 
 18 
 19 
 
 ...do 
 ...do 
 
 2,820 
 2,700 
 
 3 
 3 
 
 17 
 12 
 
 19 to 25 
 20 to 27 
 
 16 
 14 
 
 9 
 11 
 
 170 
 192 
 
 198 
 221 
 
 98 
 97 
 
 20a ... 
 21o.... 
 22 
 23. . 
 
 ...do.... 
 ...do 
 Aug. 31 
 do . 
 
 1,851 
 2,267 
 2,809 
 2,699 
 
 3 
 3 
 3 
 3 
 
 13 
 19 
 19 
 
 18 
 
 20 to 25 
 21 to 26 
 28 to 54 
 29 to 48 
 
 12 
 14 
 39 
 31 
 
 6 
 9 
 5 
 13 
 
 144 
 192 
 224 
 204 
 
 172 
 221 
 258 
 240 
 
 98 
 94 
 83 
 95 
 
 24. ... 
 
 ...do.... 
 
 2,049 
 
 4 
 
 15 
 
 30 to 50 
 
 31 
 
 7 
 
 1% 
 
 234 
 
 66 
 
 25 
 
 do. 
 
 2,266 
 
 3 
 
 19 
 
 30 to 66 
 
 49 
 
 11 
 
 219 
 
 270 
 
 57 
 
 26. 
 
 .do .. 
 
 2,262 
 
 4 
 
 14 
 
 29 to 52 
 
 34 
 
 i 
 
 234 
 
 272 
 
 95 
 
 27 a 
 
 do 
 
 39 
 
 4 
 
 9 
 
 
 ( 6 ) 
 
 
 
 
 
 28 a 
 
 do 
 
 2,344 
 
 2 
 
 14 
 
 29 to 50 
 
 32 
 
 7 
 
 192 
 
 230 
 
 97 
 
 34 
 35... . 
 
 Oct. 1 
 ...do.... 
 
 2,780 
 2,942 
 
 4 
 4 
 
 36 
 34 
 
 167 to 182 
 170 to 185 
 
 21 
 26 
 
 5 
 
 8 
 
 91 
 
 85 
 
 276 
 276 
 
 90 
 
 87 
 
 36 
 
 do 
 
 2,838 
 
 4 
 
 36 
 
 166 to 186 
 
 31 
 
 5 
 
 94 
 
 276 
 
 92 
 
 37. 
 
 .do. . 
 
 2,570 
 
 4 
 
 37 
 
 169 to 186 
 
 25 
 
 4 
 
 92 
 
 281 
 
 77 
 
 38 
 
 ...do.... 
 
 3,383 
 
 4 
 
 35 
 
 170 to 186 
 
 24 
 
 4 
 
 99 
 
 288 
 
 82 
 
 39" 
 
 do 
 
 960 
 
 6 
 
 21 
 
 173 to 188 
 
 16 
 
 3 
 
 98 
 
 281 
 
 80 
 
 40 ... 
 45 
 46 
 
 . ..do.. . . 
 Nov. 1 
 do . 
 
 2,467 
 2,961 
 1,936 
 
 4 
 
 7 
 9 
 
 31 
 99 
 
 81 
 
 165 to 185 
 151 to 170 
 139 to 158 
 
 29 
 
 13 
 11 
 
 3 
 
 8 
 9 
 
 90 
 69 
 60 
 
 279 
 239 
 236 
 
 84 
 6 
 4 
 
 47. . 
 
 ...do... 
 
 2,281 
 
 10 
 
 80 
 
 118 to 125 
 
 7 
 
 21 
 
 37 
 
 213 
 
 .09 
 
 48 
 
 do 
 
 991 
 
 20 
 
 118 
 
 154 
 
 
 
 25 
 
 25 
 
 200 
 
 .1 
 
 49 
 
 do . 
 
 2,855 
 
 8 
 
 151 
 
 138 to 158 
 
 13 
 
 13 
 
 76 
 
 244 
 
 4 
 
 50a 
 
 ...do.... 
 
 1,985 
 
 9 
 
 82 
 
 117tol68 
 
 15 
 
 21 
 
 78 
 
 253 
 
 3 
 
 51 a . 
 
 do 
 
 1,896 
 
 9 
 
 78 
 
 122 to 169 
 
 18 
 
 5 
 
 73 
 
 244 
 
 / 
 
 61 
 
 Nov 30 
 
 (c) 
 
 
 
 
 
 
 
 
 
 62 
 
 do 
 
 3,207 
 
 58 
 
 54 
 
 57 
 
 4 
 
 20 
 
 27 
 
 187 
 
 1 
 
 63 
 
 do 
 
 2,103 
 
 98 
 
 20 
 
 50 to 60 
 
 11 
 
 10 
 
 91 
 
 249 
 
 18 
 
 64. .. 
 
 ..do... 
 
 3,023 
 
 38 
 
 87 
 
 51 to 68 
 
 11 
 
 7 
 
 57 
 
 215 
 
 4 
 
 65 
 
 do 
 
 357 
 
 70 
 
 40 
 
 
 (b) 
 
 
 
 
 
 
 72 
 
 Dec 29 
 
 (c) 
 
 
 
 
 
 
 
 
 
 73 
 
 .. do 
 
 3,180 
 
 63 
 
 18 
 
 56 to 66 
 
 14 
 
 13 
 
 46 
 
 181 
 
 1 
 
 74 
 
 .do. 
 
 4,272 
 
 39 
 
 63 
 
 48 to 80 
 
 25 
 
 7 
 
 73 
 
 207 
 
 35 
 
 75 
 
 do 
 
 1 970 
 
 46 
 
 37 
 
 
 (6) 
 
 
 
 
 
 76 
 
 77 
 
 1908 
 Jan. 1 
 
 1907 
 Dec 30 
 
 3, 173 
 
 (c) 
 
 63 
 
 24 
 
 48 to 07 
 
 14 
 
 8 
 
 69 
 
 201 
 
 25 
 
 82... 
 83 
 
 1908 
 Feb. 4 
 Feb. 3 
 
 4,276 
 3,900 
 
 28 
 29 
 
 39 
 36 
 
 48 to 65 
 45 to 62 
 
 26 
 25 
 
 4 
 
 6 
 
 99 
 76 
 
 189 
 172 
 
 81 
 
 86 
 
 a Eggs were not counted, 
 larvae had died. 
 6 Eggs failed to hatch, 
 c Did not oviposit. 
 
 40 
 
 The unhatched eggs and the larvae in each tube were counted after all the
 
 APPENDIX. 41 
 
 TABLE 1. Individual records of ticks used in experiments Continued. 
 
 Num- 
 ber of 
 tick. 
 
 Date col- 
 lected. 
 
 Number 
 of eggs de- 
 posited. 
 
 Preovi- 
 posilion 
 period. 
 
 Ovi- 
 posit ion 
 period. 
 
 Incuba- 
 tion pe- 
 riod. 
 
 Hatch- 
 ing pe- 
 riod. 
 
 Mini- 
 mum 
 longev- 
 ity. 
 
 Maxi- 
 mum 
 longev- 
 ity. 
 
 Entire 
 time. 
 
 Per cent 
 hatched. 
 
 84... 
 85 
 
 87 
 
 1908 
 Feb. 4 
 Jan. 30 
 .do 
 
 806 
 3,620 
 3,725 
 
 Days. 
 36 
 35 
 34 
 
 Days. 
 22 
 33 
 43 
 
 Days. 
 53 to 63 
 49 to 63 
 48 to 64 
 
 Days. 
 14 
 26 
 26 
 
 Days. 
 
 6 
 7 
 2 
 
 Days. 
 
 77 
 86 
 81 
 
 Days. 
 
 177 
 186 
 176 
 
 39 
 t>5 
 72 
 
 88<J.. . 
 
 89a. 
 
 Jan. 29 
 do 
 
 3,269 
 3,718 
 
 37 
 37 
 
 36 
 41 
 
 48 to 65 
 47 to 65 
 
 25 
 
 18 
 
 7 
 21 
 
 59 
 64 
 
 156 
 156 
 
 34 
 14 
 
 95 
 98o.... 
 105.... 
 106 
 
 Feb. 27 
 Feb. 28 
 Mar. 26 
 do 
 
 2,302 
 2,925 
 4,559 
 2,680 
 
 10 
 
 8 
 5 
 6 
 
 24 
 36 
 34 
 24 
 
 47 to 64 
 45 to 62 
 36 to 53 
 43 to 53 
 
 18 
 27 
 13 
 12 
 
 4 
 2 
 7 
 
 7 
 
 94 
 80 
 90 
 98 
 
 162 
 143 
 149 
 155 
 
 62 
 96 
 77 
 
 78 
 
 107 
 
 . .do 
 
 2,731 
 
 8 
 
 14 
 
 43 to 52 
 
 15 
 
 12 
 
 101 
 
 161 
 
 66 
 
 108 
 
 do 
 
 3,024 
 
 5 
 
 17 
 
 44 to 53 
 
 12 
 
 11 
 
 101 
 
 159 
 
 89 
 
 109 
 
 do 
 
 4,035 
 
 6 
 
 23 
 
 39 to 53 
 
 14 
 
 6 
 
 97 
 
 155 
 
 95 
 
 liofc.. 
 
 lllfr. . 
 1126 
 
 Mar. 29 
 ...do 
 do 
 
 3,712 
 3,405 
 3.622 
 
 4 
 5 
 4 
 
 35 
 27 
 26 
 
 37 to 52 
 38 to 51 
 39 to 51 
 
 14 
 16 
 14 
 
 13 
 5 
 5 
 
 92 
 89 
 
 88 
 
 146 
 144 
 
 144 
 
 92 
 92 
 
 97 
 
 113 fr 
 
 do . 
 
 3,796 
 
 4 
 
 25 
 
 37 to 51. 
 
 15 
 
 10 
 
 103 
 
 156 
 
 93 
 
 125.... 
 126 
 
 Apr. 29 
 ...do 
 
 4,244 
 3,966 
 
 4 
 6 
 
 22 
 19 
 
 24 to 36 
 26 to 34 
 
 18 
 12 
 
 5 
 6 
 
 113 
 
 89 
 
 152 
 
 128 
 
 96 
 33 
 
 127 
 
 do 
 
 3,929 
 
 6 
 
 25 
 
 24 to 33 
 
 18 
 
 4 
 
 118 
 
 156 
 
 98 
 
 128 
 
 do . 
 
 4.385 
 
 4 
 
 24 
 
 25 to 36 
 
 16 
 
 9 
 
 116 
 
 156 
 
 96 
 
 129 
 
 .do 
 
 5,105 
 
 6 
 
 24 
 
 24 to 33 
 
 18 
 
 7 
 
 116 
 
 154 
 
 84 
 
 130 &. . 
 
 ...do 
 
 3,942 
 
 6 
 
 23 
 
 24 to 33 
 
 17 
 
 9 
 
 105 
 
 145 
 
 98 
 
 1316.. 
 
 ...do... 
 
 3,949 
 
 7 
 
 19 
 
 23 to 33 
 
 13 
 
 10 
 
 93 
 
 133 
 
 98 
 
 132 b . . 
 1336. 
 
 ...do 
 .do 
 
 4,035 
 3,246 
 
 6 
 
 7 
 
 27 
 21 
 
 24 to 33 
 24 to 32 
 
 17 
 18 
 
 6 
 10 
 
 128 
 79 
 
 173 
 
 122 
 
 98 
 93 
 
 134 o .. 
 
 ..do 
 
 
 6 
 
 24 
 
 23 to 33 
 
 22 
 
 5 
 
 92 
 
 131 
 
 
 135 a. . 
 
 ...do... 
 
 
 5 
 
 22 
 
 25 to 34 
 
 19 
 
 11 
 
 % 
 
 138 
 
 
 136 a 
 
 do 
 
 
 G 
 
 21 
 
 24 to 33 
 
 16 
 
 6 
 
 91 
 
 131 
 
 
 137 a 
 
 do. 
 
 
 6 
 
 26 
 
 25 to 34 
 
 17 
 
 19 
 
 94 
 
 131 
 
 
 138 c. . 
 
 ...do 
 
 
 
 22 
 
 24 to 32 
 
 20 
 
 
 108 
 
 149 
 
 
 
 
 
 
 
 
 
 
 
 
 
 a Eggs were placed in test tubes directly on moist sand. No water was added to the sand after the tube 
 was made. 
 
 ft Eggs were placed in test tubes provided with two cardboard disks. No water was added to the 
 sand after the tube was made. 
 
 c Eggs were floated on water in test tubes.
 
 42 
 
 BIOLOGY OF THE TEXAS-FEVER TICK. 
 
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