UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE GARDEN CENTIPEDE F. H. WYMORE BULLETIN 518 November, 1931 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA THE GARDEN CENTIPEDE F. H. WYMOEEi The garden centipede, Scutigerella immaculata (Newp.), is not a new pest in many truck and field crop sections of California. Thirty years ago asparagus in certain sections of the Sacramento and San Joaquin Delta region was so seriously damaged by the centipede that many large fields were plowed out, and in the same areas today it is still considered the worst pest of asparagus. Many reports have also been received of serious injury to various other crops throughout the state. This pest was first reported in California by Woodworth in 1905 and first came to the writer's attention in the fall of 1922. The data discussed in this paper were obtained during 1922 to 1925 with subsequent observations up to the present time. DISTRIBUTION The garden centipede is known to occur in Denmark, England, France, Germany, Austria, Czechoslovakia, Italy, and in Sweden as far as 60° north latitude (fig. 1). In Africa it is known in Algeria; in South America, in Buenos Aires, Argentina; in North America it occurs in Cordoba, Mexico ; in Canada, near Victoria, B. C. ; and in the United States (fig. 2), in California, Connecticut, Georgia, Illinois, Indiana, Kentucky, Louisiana, Massachusetts, New York, Ohio, Oregon, Pennsylvania, Texas, and Utah. In 1928 specimens were received from Hawaii where it is reported as a serious pest on pineapples. Oregon reports it injurious to many crops in 9 counties, and Utah in 3 counties. In California it has been reported as a pest to various crops in 14 counties (fig. 3). The world-wide distribution of this species indicates that any area might be subject to its attacks. LIFE HISTORY AND HABITS The garden centipede, 2 Scutigerella immaculata (Newp.), as the name implies, is a centipede-like animal belonging to the class Symphyla, members of which are considered by some students as 1 Associate in Entomology. 2 The garden centipede is not a true centipede, and is distinguished from the latter by having only twelve pairs of legs in the adult and fewer in the young, no eyes, and the genital aperture located in the venter between the fourth pair of legs. University of California — Experiment Station Fig. 1. — The dark areas indicate the known distribution of the garden centipede throughout the world. Fig. 2. — The dark areas indicate the known distribution of the garden centipede in the United States. Bul. 518] The Garden Centipede possibly ancestral to both insects (Class Insecta) and true centipedes (Class Chilopoda). The members of this group are delicate, soft-bodied animals scarcely % inch in length. They are pure white in color except that vi^ s ' It »*• I- ! T E H A 1 \5LENN 'VfclfRRA ° rXV v \ V\ /: i 1UURE \ %\ KERN X SAN BERNARDINO >»\ ,* I r ^ 1-7^, Vl R i V E R S i Fig. 3. — The dark areas indicate the known distribution of the garden centipede in California. the body may be tinted by the food material in the alimentary tract, easily visible through the thin body wall; for example, when feeding on tender white asparagus shoots, they are almost translucent white, while red radishes produce a pinkish cast; garden beets, a deep red, and decaying vegetation, etc., a brownish color. 6 University of California — Experiment Station The adults (fig. 4C) vary in length from 3 to 7 mm (% to % inch) ; they have twelve pairs of legs and each of the fourteen body segments is equipped dorsally with a prominent chitinous plate known as a scute. The garden centipede has no true eyes, orientation being effected by two many-jointed antennae or feelers which are kept con- stantly in motion as they move about. The delicate mouth-parts are of the chewing type and capable of inflicting considerable damage upon the tender portions of plants. From the last body segment there extend posteriorly two pointed appendages known as cerci, and in the Fig. 4. — The garden centipede, Scutigerella immaculata (Newport). A, Eggs (15 times natural size) ; B, eggs and newly hatched young (8 times natural size) (photo furnished by A. E. Michelbacker) ; C, adult (10 times natural size). tip of each is the opening of a spinning gland. Through each of these openings a very delicate web may be spun which is strong enough to support the weight of the centipede. The spinning of these webs has often been observed when the centipedes were suddenly shaken from a clod of dirt or upon picking them up with a needle or camel's hair brush. While studying them under the microscope, they have been seen to thrust down the tips of the cerci suddenly and spin a short web as they descended the wall of a small depression. These observations seem to indicate that this web may be used as a sort of anchorage. It is claimed by some students that the runways are lined with the webs, which thus serve as a 'lifeline' so that the centipedes may safely Bul. 518] The Garden Centipede 7 retrace their steps, and that the eggs are often covered with webbing. The writer's observations have been that very few webs appear in the natural runways or on the eggs as found in the fields, but that after keeping the centipedes or the eggs in a moist container for a few days a network of what seem to be webs appear all over the sur- face of the soil and the eggs. However, a microscopic examination showed that the majority of these web-like structures were mycelium threads of some fungus, which might be mistaken for a web. The centipedes prefer the cool moist earth, but they may remain alive for several months in a can of earth at room temperature without the addition of moisture. S. R. Williams (1907) 3 found them breeding rather commonly in decayed logs. In strawberry beds where surface irrigation is practiced they may be found near the surface of the soil throughout the summer, but in fields that become dry they follow the moisture as it recedes. Too much moisture also retards their development, but, generally speaking, conditions that will promote vigorous growth of truck and field plants seem to be ideal for their development. The centipedes deposit their eggs (fig. 4A) in the runways in moist soil, usually in a cluster from 4 to 20, rarely more. They are tiny (0.5 mm in diameter), spherical, and covered with a network of minute projections. When first laid, they are pure white, but as the time for hatching approaches they become a dark olive-buff color (Ridgeway, 1912, plate XL). Centipede eggs may be found in the fields of the Delta region at almost any time of year ; however, they are most numerous in the spring during the latter part of April and throughout May. In one asparagus field (in 1924 and 1925) where the ground was kept fairly moist in the late summer, many eggs were found during the month of Sep- tember, while at the same time none were found in fields where the soil had become rather dry, even though the adult centipedes were numerous and there had been a heavy production of eggs in the spring and early summer. One grower, located near the coast in San Mateo County, reported that in 1930 centipede eggs Avere very abundant in his well-irrigated strawberry beds during the month of November. The proper amount of moisture would, therefore, seem rather an important factor in egg production. During the early summer months the eggs hatch within a week or ten days. The centipede eggs evi- dently have a very high fertility for seldom is an unhatched egg 3 See " Literature Cited" at the end of the bulletin for complete data on citations, which are referred to in the text by author and date of publication. 8 University of California — Experiment Station found in the field. In the laboratory they are sometimes attacked by a fungus which prevents hatching. The newly hatched young (fig. 41?) are minute, white, less than 1/16 inch in length, with ten dorsal segments, six pairs of legs, and six-jointed antennae. At this stage they appear to the naked eye to resemble an insect known as the seed springtail. Six molts occur before the centipedes acquire the fourteen dorsal segments and the twelve pairs of legs. At room temperature the first molt occurs 36 to 72 hours after hatching. At this time an additional pair of legs is acquired, the antennae become thirteen-jointed, and the movements of the young become more typical of that of the adults. In the laboratory the newly emerged young seldom move more than a short distance from the nest (fig. 45) and apparently do little or no feeding until after the first molt. An examination of the aban- doned nests in the soil almost always reveals many cast skins of the first molt in close proximity to the empty egg shells, indicating that the activities of the young under natural conditions are similar to those reared in the laboratory. The five successive molts occur at intervals of from ten days to two weeks. At each molt an additional body segment, bearing a pair of legs, is acquired just in front of the last segment and the antennae increase two or three segments in length. Additional molts may occur at various intervals even after the centipedes have acquired the twelve pairs of legs, but there is no increase in the number of legs or body segments. The life cycle extends over a period of several months. Under laboratory conditions centipedes have been kept alive in moist soil for nine or ten months. Filinger (1928) reports that his rearing records show certain individuals to have lived eleven to twelve months. ECONOMIC IMPORTANCE Apparently the first reference made to this centipede as a pest to agriculture was by Woodworth (1905, 1905 a ), who reported it as "a very serious pest to asparagus on Boldin Island and about Sacra- mento. " Davis (1912) reported it as occurring in 1908 on Asparagus plumosus and smilax in Illinois greenhouses. Essig (1915, pp. 20, 21) refers to it as the lima bean symphylid but states that it also attacks tender shoots of asparagus and morning-glory and germinating pea seeds, and that it is distributed throughout California. Lovett (1921) reported that it was generally distributed throughout the state of Bul. 518] The Garden Centipede Oregon and "attacks all kinds of sprouting seed, being particularly partial to peas and beans. Growing plants also suffer injury." Since 1924 many references have appeared in literature mentioning this symphylid as a serious pest to the various crops throughtout the country. On the Pacific Coast, and in Hawaii and certain sections of western Europe (fig. 1), the garden centipede is primarily a pest to crops grown out of doors, while in the eastern states injury is con- fined primarily to greenhouse plants. These little animals are subterranean and therefore attack, for the most part, the underground portions of the plants, or a leaf of a plant that comes in direct contact with the soil. The centipedes injure Fig. 5. — Plants showing centipede injury: A, radishes; B, garden beets. the plants by eating numerous holes or pits (figs. 5 and 6) into the stems or roots, usually just through the epidermis, causing wilting and often death. In the spring of 1929 the writer observed a 30-acre field near San Jose, California, that had been practically denuded of young spinach plants by this pest. In the same season certain areas from 1 to 10 acres in extent in large sugar-beet plantings in the Sacramento River Delta were observed on which the seedlings of the third successive planting had been almost completely destroyed. In both cases the plants were killed before they were 3 inches high. 10 University of California — Experiment Station Most of the asparagus used for canning purposes is grown beneath large ridges (fig. 7) thrown up over the crowns. The tender white shoots produced in this environment are extremely susceptible to centipede injury. It is very common to find fields of 30 or 40 acres so heavily infested that practically all of the shoots are perforated with small pits (fig. 8). At this degree of infestation many shoots are completely killed by girdling below ground or are so seriously injured Fig. 6. — Bean plants showing centipede injury: A, wax bean seeedlings; B, mature cowpea plants. that the ferns ripen prematurely during the summer (fig. 9). When a field of asparagus becomes so heavily infested, it is seldom profitable to cultivate the plants any longer, and, therefore, the crop is usually plowed out and other crops planted. Often this procedure, as in the case of sugar beets and spinach described above, is not successful. Alfalfa and celery have shown considerable resistance to the centipede attack ; however, in one case alfalfa of three successive seedings was destroyed on a 20-acre field. Bul. 518] The Garden Centipede 11 Fig. 7. — Section of a cutting ridge with dirt removed to show the succulent white shoots, that part of the plant to which the centipedes do greatest damage. Fig. 8. — Asparagus shoots showing nature of centipede injury. 12 University of California — Experiment Station Fig. 9. — Asparagus field showing premature ripening of the ferns due to centipede injury. PROBABLE SOURCES OF INFESTATION AND LOCAL DISSEMINATION In spite of the fact that the garden centipede represents rather an ancient animal and is likely to occur in almost any locality of the country, there are certain areas in the Delta region in particular, in which it either does not occur or at least does not occur in sufficient numbers to make its presence known by injury to plants grown in that vicinity. The fact becomes evident in fields newly planted to asparagus; for the centipedes very often first make their appearance in certain localized areas, such as in one corner of a field or in a circular area adjacent to the river levee. New infestations have some- times become evident in small slightly elevated spots almost in the center of a newly reclaimed swamp or recently flooded area. This would indicate that infestation might have originally taken place through floating logs, etc., during the flood. The growers have often requested information as to how they might prevent the spread of this pest from such sources. It has been observed that the principal spread from the original infestation is with the direction of the rows, the lateral spread being very slow. Therefore it seems only reasonable to assume that cultural practices are in a large measure responsible for the distribution of the centi- pedes from one portion of the field to another. Farm tools, such as plows, cultivators, drags, etc., and particularly the asparagus ridge Bul. 518] The Garden Centipede 13 leveler (fig. 10), would seem likely agents. This device usually con- sists of a large wooden beam 8 inches square and about 35 feet long weighted down with a railroad iron. It is drawn with a tractor from one end of the field to the other, leveling the large cutting ridges in one operation. Large quantities of centipede-infested soil (fig. 10) may thus be transported the full length of the asparagus field. Infested soil about the roots of plants is always a possible source of new infestations ; therefore due precautions should be exercised in transferring plants into noninfested soil. Fig. 10. — The asparagus ridge leveler showing how quantities of centipede-infested soil may be transported across the field. The feeling that barnyard manure is a very serious source of infes- tation and that it encourages the reproduction of the garden centi- pedes, is general among the asparagus growers. One report from an eastern state, however, credits barnyard manure with having repellent properties. In a number of observations the writer has never been able to find the centipedes in the main mass of a manure heap but found them in enormous numbers about the plant roots growing around the edge of the heap where the manure was very largely decomposed. Much care should, therefore, be exercised when moving the manure to the fields so as not to scrape too close to the infested area. While there may be a possibility of carrying centipedes in the young crowns from the nursery to the permanent asparagus beds, this seems highly improbable. The ordinary curing process, if prop- erly done, should destroy any living centipedes; for upon exposure to relatively dry air they soon become inactive and die within a short time. Certain growers have expressed the fear that the centipedes might be spread through the lug boxes brought back from the cannery. With 14 University of California — Experiment Station the modern methods of handling the asparagus this would seem im- possible ; for the shoots are usually hauled to the packing sheds in small trucks, thoroughly washed, and then placed into clean boxes before being taken to the cannery. CONTROL Experiments with Flooding. — When properly done, flooding has so far proved the most practical means for the control of the garden centipedes if the asparagus or other fields are comparatively level and adjacent to an abundant supply of relatively cheap water. Fig. 11. — A good type of levee commonly used to retain the water on flooded fields. Approximately 400 acres of a large asparagus ranch on Ryer Island were kept submerged for from three to four weeks in the winter of 1924-25 in an attempt to destroy the pests, which were numerous on portions of these fields. It was necessary to construct over 5 miles of levee between 4 and 5 feet high (fig. 11) to retain the water on this area. The water for this project was pumped from the Sacramento River by three 12-inch pumps, operating day and night for three weeks or so until the fields became thoroughly covered (fig. 12), after which one pump was able to hold the water at the desired level. Numerous observations were made to determine the effectiveness of the flooding. Upon stirring the surface of the mud under water Bul. 518] The Garden Centipede 15 with foot or a hoe, the living" centipedes, as well as the dead, would float to the surface of the water. At the end of ten days only an occasional living centipede could be located in the well-flooded areas; that is, where the field was covered with at least one foot of water and no stubble was standing above the surface. On the other hand, in areas where the stubble or ripe tops were not completely sub- merged (fig. 12), living centipedes could still be found after being under a foot or so of water for four weeks. These observations were substantiated by making- a careful check of these fields during the following cutting season. This was done by an examination of the Fig. 12. — A view of flooding for the control of the garden centipede. The field to the right of the levee is thoroughly covered, whereas the ground about the buildings and at the end of the rows on the left now being flooded may prove a source for reinfestation of the whole field within a year or so. tender white asparagus shoots that were cut and arranged in small bunches on the ridge of every third or fourth row by the cutting- crew. Where the fields were thoroughly covered and the water held at a depth of a foot or more for three weeks, no signs of centipede injury were observed at all during the first cutting season 4 following- the flooding. On areas not thoroughly covered, the centipede feeding marks became apparent on the shoots toward the latter part of the season. On the strength of the results obtained in this flooding experiment, 736 acres were flooded the following winter, 1925-26, with results similar to those of the season before. 4 The cutting season for canning asparagus normally continues from April 1 to July 1. 16 University of California — Experiment Station The cost of the flooding in 1924-25 amounted to $11.50, and that of 1925-26 to $17.50 an acre. The great difference in cost of the two projects may be explained by the fact that the tenants of the flooded farms furnished all the hand labor for reenforcing levees, etc., in 1925-26, whereas tenants were not farming the land under the second project, and all the expense for the hand labor was figured in with the total cost. The plots in the second project were not so level as those of the first so that more levees were constructed in the latter. Considerable quantities of the asparagus tops were piled up along the inside of the levees to break the force of the waves. This afforded some protection to the newly constructed levees and was an improve- ment over the plain dirt levees upon which the waves did so much damage the season before. In the winter of 1928-29 an area of 698 acres was flooded for three to four weeks at a cost of $8.50 an acre. A part of this area had previously been flooded in either the 1924-25 or the 1925-26 projects and a considerable portion of the old levees was used, thereby greatly reducing the total cost of the treatment. A small field in a different locality to the others just mentioned was thoroughly flooded for one month (December 5, 1929, to January 5, 1930) at a cost of a little more than $9.00 an acre. Although there were no signs of the centipedes during the next cutting season, it was decided to flood the field again the following season to stimulate the plants to produce a heavy crop of green asparagus for the early spring market. All the levees about this field were carefully pre- served during the summer so that it was not necessary to construct any levees at all for the second season of flooding. Therefore, the cost of holding the water on this same area from December 3, 1930, to January 6, 1931, was approximately $0.75 an acre. In every instance cited, the water used for flooding the fields was pumped from the river by power from an electric or gasoline motor. Suggestions for the Best Success with Flooding for Control. — Considerable attention should be given to checking on the level of the fields in preparation for the construction of the levees. The human eye has in many cases proved a poor leveling instrument, and since water always seeks the lowest level, much trouble and extra expense may be avoided by making sure that the levees are placed in the proper location. Another item worthy of consideration in the place- ment of the levees is that, if at all possible, they should be placed upon noninfested soil. Often a field along one side of a canal or irrigation ditch may be heavily infested with centipedes, whereas there is no evidence that they occur on the other. In such a case it is Bul. 518] The Garden Centipede 17 highly desirable to place the levee on the noninf ested field ; for the centipedes which occur in the soil will migrate into the levee as the water table is raised by flooding. A centipede-infested levee may become a source of reinfestation for the recently flooded field. If the construction of a levee on infested soil cannot be avoided, then a thorough treatment of the levees with carbon disulfide while the water is on the fields will greatly reduce the centipede population. An application of carbon disulfide at the rate of 2% ounces to a hole in holes 18 inches apart and 1 foot deep on the crest of the levees, and 2 ounces to a hole in holes 1 foot apart on the outside (away from the water) should destroy most of the centipedes in these areas. Any packing treatment of the soil and the wetting of the surface imme- diately after the application of the carbon disulfide will greatly aid in the fumigation. The Effect of Flooding Upon Asparagus Plants and the Soil. — Not only has flooding proved the most efficient means of controlling the garden centipede in the asparagus fields, but also, in most cases where it has been practiced, the crowns have been stimulated to an unusually early growth. In 1925 the water was drained from the flooded fields on January 14 and on February 4 six boxes of asparagus were cut from this area, while February 17 was the earliest cutting date on nonflooded fields. The plants on flooded fields also continue to produce much heavier than those on nonflooded fields for several weeks during the season. Certain growers have taken advantage of flooding to produce asparagus for the early season market, and in this they have usually been fairly successful. Occasionally, when the temperature is low at the time the water is drained from the flooded fields, or soon after, a decided retarding effect on the growth of the plants may occur for a short time. When the temperature rises again, however, in a few days the production per acre on the flooded fields surpasses that of the nonflooded area. In 1930 such a reaction oc- curred, on nonflooded fields in the Delta district the earliest cutting date was February 9 and on the flooded area February 17. This spring (1931) there was, however, in these same fields a decided stimu- lating effect on the growth of the plants on the flooded area. In this case February 13 was the earliest cutting date as compared with March 10 on the nonflooded fields. Complaints have been registered by certain growers who produce asparagus for canning that the stimulation due to flooding is so great that the tendency is to produce many small spears per crown rather than, as normally, a few large ones. Experimental data show that the removing of the shoots from a crown over too long a period 18 University of California — Experiment Station of time so weakens the plant that eventually all the spears produced are much smaller. There is a possibility that a similar reaction occurs in the plants on flooded fields where the grower has contracted to sell asparagus for canning, since a great amount of asparagus has already been cut before the canning season begins. A finely pulverized soil is one of the chief requirements in the construction of a good cutting ridge for the production of white or canning asparagus. Flooding has a tendency to puddle the heavy clay-type soils and where this has occurred, the growers have experi- enced considerable difficulty in working the ground back into a good physical condition before the cutting season begins. One grower largely overcame such a condition in his field by growing an intercrop of soybeans in late summer (1930) after the first cutting season. This vegetation, together with the ripe tops, was disked into the soil in the fall before flooding. At present the soil in this field is in better physical condition than after the first flooding. Soil Fumigants. — Of the numerous soil fumigants tested for the control of the garden centipede, only calcium cyanide and para- dichlorobenzene showed favorable results as applied in asparagus fields. Both of these materials were tested rather extensively, being applied at various times during the season and under varying soil conditions. In small test plots established May 25, 1923, with a soil temperature of 68° Fahrenheit, paradichlorobenzene exhibited con- siderable more killing power than calcium cyanide. Portions of aspara- gus rows were treated separately at the rate of % ounce of the materials to 3 linear feet on each side of the ridge in a furrow 3 or 4 inches deep. No living centipedes were found in the paradichloroben- zene plot, and approximately 80 per cent were dead in the calcium cyanide plot. However, under general field conditions these two mate- rials did not prove so satisfactory. On March 14, 1924, approximately % acre of asparagus was treated with granular calcium cyanide at the rate of 125 pounds per acre. The material was applied, with a machine applicator attached to an 8-inch garden plow, in three furrows on either side of the rows to a depth of 6 or 7 inches. Although large numbers of the centipedes were killed 3 or 4 inches from the point of application, the gas did not penetrate the soil sufficiently to be of any practical value as a control. On May 5, 1924, % acre was treated at the rate of 300 pounds per acre, Even at this dosage no greater percentage of the centipedes were killed than on the area where 125 pounds per acre whs used. On July 8, 1924, granular cyanide at the rate of 400 pounds per acre applied between the rows with a grain drill to a depth of Bul. 518] The Garden Centipede 19 4 or 5 inches had very little effect on the centipedes. A dust mulch of 3 or 4 inches and a soil temperature of 75° F probably allowed the gas to escape too rapidly. Calcium cyanide dust at the rate of 200, 300, 350, 400, and 500 pounds per acre was applied to 150-foot sections of asparagus rows on June 10, 1925. This material was applied as close to the crowns as possible by splitting- the ridges with a two-way plow. The dust was applied by hand in the furrows and covered immediately with a ridging disk. The new shoots in these plots were free from centipede injury for ten days to two weeks, but by June 26 fully 50 per cent of the shoots were again being damaged. No further observations were possible during the season because the ridges were leveled on July 1. Paradichlorobenzene was applied similarly to calcium cyanide. In none of these field tests did it surpass the results obtained with calcium cyanide. Carbon disulfide applied at the rate of 2% ounces to a hole, in holes 18 inches apart each w r ay and about 10 inches deep, was found by deOng 5 to be very effective in killing the garden centipede in asparagus fields of the Delta country. Small plots 30 feet square, isolated by a 3-foot ditch partially filled with water, were used in his experiments. A treatment of the above recommended dosage would require 3,344 pounds of carbon disulfide per acre, and at 7 cents a pound would cost $234 an acre for the material. Riley (1929) claims good control of the centipedes in greenhouses with a dosage of 1 ounce of carbon disulfide to every square foot of soil. At this dosage it would require 2,719 pounds of material per acre at a cost of $190, which at the present margin of profit on asparagus would hardly seem practical. For the treatment of small isolated or newly discovered infesta- tions or infested flooding levees carbon disulfide has proved very efficient in destroying large numbers of the centipedes. It is generally recommended that to obtain the best results from the use of carbon disulfide it should be applied only when the soil temperature is 65° F or higher and the soil should be wet down immediately following the application to prevent the gas from escaping too rapidly. Experiments are now in progress with a slowly volatilizing form of carbon disulfide and carbon disulfide emulsion for control of the centipedes, but these have not been sufficiently tested to warrant any recommendations as to their use on this pest. 5 deOng, E. K. Scolopetidrella oalifornica considered economically. Unpub- lished manuscript. 1913. 20 University of California — Experiment Station In both laboratory and field tests orthodichlorobenzene did not measure up to the results obtained with calcium cyanide or para- dichlorobenzene. In addition, this treatment caused blackening and hardening of the tender asparagus shoots for a few days, but there was no noticeable stimulating or retarding effect of the plants from any of the other materials. Also, the flavor of the asparagus was greatly influenced by the orthodichlorobenzene, and the taste persisted even after the shoots were cooked for 20-30 minutes. Cultivation. — The intensive methods of soil tillage are no doubt responsible for the destruction of great numbers of these fragile- bodied centipedes, but the most intensive cultivation has not, accord- ing to the writer's observations, controlled this pest. Natural Enemies. — Very little is known concerning the natural enemies of the garden centipede. A white, rapidly moving gamasid mite has been observed to attack injured centipedes both in the field and in the laboratory. Just what effect this or other predators have on the centipedes under natural conditions is difficult to determine. Four species of true centipedes (Chilopoda), Ethopoly xanti Wood, Oabius tiganus Chamberlain, Taiyuna Occident alis Meinert, and Gnathomerium melanonotum Wood, thrived on garden centipedes for several months in the laboratory. These animals, after being starved for a few days, voraciously attacked in rapid succession ten or fifteen of their smaller cousins which were placed within the cage. Filinger (1928) credits two species of the true centipedes, Lithobius forficatus Linn, and Poabius bilabiatus Wood, with having kept the garden centipedes under control in a greenhouse in Ohio. Larvae of various predaceous ground beetles are often found in the same habitat with the garden centipedes, but they have not been observed to attack them. Repellents. — The following materials were applied to asparagus rows above the crowns of the growing plants immediately before the normal cutting-season ridges (fig. 7) were thrown up: (1) 910 pounds of lime refuse, of a good quality, to 1,000 feet; (2) 500 pounds of air- slaked lime to 800 feet; (3) 300 pounds of hydrated lime to 600 feet; (4) 125 pounds of a so-called * combined fertilizer and insecticide' to 300 feet; (5) 50 pounds of tobacco dust to 300 feet. Observations continued every week for six weeks after the above applications and at no time were there any noticeable repelling effects. Like results were obtained by certain growers with sulfur applied in a similar manner. Bul. 518] The Garden Centipede 21 SUMMARY The so-called 'centipede' discussed in the foregoing paper is most injurious to plants growing out of doors during the spring and sum- mer months and attacks the tender underground portion of practi- cally all kinds of plants, eating numerous small holes or pits into the stems and roots, causing wilting and often the death of the host. Indications are that infested soil carried on farm tools or on the roots of plants may be responsible for the spread of the centipedes in the fields. While the centipedes are not likely to be found in the main mass of a manure heap, they are commonly found in the edges where the manure is well decayed and vegetation may be growing. Much care should, therefore, be exercised when moving manure to the fields so as not to gather up the infested material. Flooding has proved the only practical method for controlling the garden centipede in asparagus fields. Levees for holding the water should be substantially constructed and so placed that all portions of the field may be covered to a depth of 1 foot or more for two to three weeks. The proper time for flooding is during the winter when the plants are in a dormant condition. All infested levees or small newly discovered field infestations should be treated with carbon disulfide at the rate of 2y 2 ounces to a hole, in holes 12 inches deep and 18 inches apart each way. Soil fumigants have not proved practical as a general field treat- ment for control of this centipede. ACKNOWLEDGMENTS The writer wishes to express his appreciation of the helpful sug- gestions and criticisms given by Professor W. B. Herms, Professor E. 0. Essig, and Mr. G. H. Vansell. Much credit is due Mr. J. Van Tonningen and others of the California Packing Corporation for their enthusiastic cooperation in the experiments conducted in their large asparagus fields. Mr. A. Brown and other growers generously donated portions of their asparagus fields for experimental purposes. 22 University of California — Experiment Station LITERATURE CITED Davis, J. J. 1912. A new fern-asparagus and smilax root borer. 27th Report of the State Entomologist on the Noxious and Beneficial Insects of the State of Illinois, p. 138. EssiG, E. O. 1915. Injurious and beneficial insects of California. California State Comm. Hort. Mo. Bui. Supplement. 541 p. Filinger, G. A. 1928. Observations on the habits and control of the garden centipede, Scutigerella immaculata, a pest in greenhouses. Jour. Econ. Ent. 21:357-360. Lovett, A. L. 1921. Myriapoda, Scutigerella sp. Insect Pest Survey Bui. 1:127. RlDGEWAY, R. 1912. Color standards and color nomenclature. 53 colored plates. Williams, S. R. 1907. Notes on S. immaculata, its eggs and larvae. Proc. 7th Internatl. Zool. Cong., Cambridge, Mass., 1912, 7:656-659. 5 figs. WOODWORTH, C. W. 1905. Asparagus attacked by centipedes. California Fruit Grower 30 (889) :1. 1905a. A new centipede of economic importance. California Jour, of Technology. 6:38-42, figs. 1-3. STATION PUBLICATIONS AVAILABLE FOE FEEE DISTKIBUTION BULLETINS No. 253. Irrigation and Soil Conditions in the Sierra Nevada Foothills, California. 263. Size Grades for Ripe Olives. 279. Irrigation of Rice in California. 283. The ©live Insects of California. 310. Plum Pollination. 381. Phylloxera-resistant Stocks. 335. C'ocoanut Meal as a Feed for Dairy Cows and Other Livestock. 343. Cheese Pests and Their Control. 348. Pruning Young Olive Trees. 349. A Study of Sidedraft and Tractor Hitches. 357. A Self-Mixing Dusting Machine for Applying Dry Insecticides and Fun- gicides. 361. Preliminary Yield Tables for Second Growth Redwood. 364. Fungicidal Dusts for the Control of Bunt. 368. Bacterial Decomposition of Olives During Pickling. 369. Comparison of Woods for Butter Boxes. 370. Factors Influencing the Development of Internal Browning of the Yellow Newtown Apple. 371. The Relative Cost of Yarding Small and Large Timber. 373. Pear Pollination. 374. A Survey of Orchard Practices in the Citrus Industry of Southern Cali- fornia. 379. Walnut Culture in California. 386. Pruning Bearing Deciduous Fruit Trees. 389. Berseem or Egyptian Clover. 392. Frtiit Juice Concentrates. 393. Crop Sequences at Davis. 394. I. Cereal Hay Production in California. II. Feeding Trials with Cereal Hays. 396. The Mat Bean, Phaseolus Aconitifolius. 404. The Dehydration of Prunes. 406. Stationary Spray Plants in California. 407. Yield. Stand, and Volume Tables for White Fir in the California Pine Region. 408. Alternaria Rot of Lemons. 409. The Digestibility of Certain Fruit By- products as Determined for Rumi- nants. Part I. Dried Orange Pulp and Raisin Pulp. 410. Factors Influencing the Quality of Fresh Asparagus After it is Harvested. 416. Culture of the Oriental Persimmon in California. 417. Poultry Feeding: Principles and Prac- tice. 418. A Study of Various Rations for Fin- ishing Range Calves as Baby Beeves. 419. Economic Aspects of the Cantaloupe Industry. 420. Rice and Rice By-Products as Feeds for Fattening Swine. 421. Beef Cattle Feeding Trials, 1921-24. 423. Apricots (Series on California Crops and Prices). 425. Apple Growing in California. 426. Apple Pollination Studies in California. 427. The Value of Orange Pulp for Milk Production. 428. The Relation of Maturity of California Plums to Shipping and Dessert Quality. 431. Raisin By-Products and Bean Screen- ings as Feeds for Fattening Lambs. 432. Some Economic Problems Involved in the Pooling of Fruit. No. 433. 435. 436. 439. 4 4 6. 447. 448. 449. 4 50. 4 52. 454. 455. 456. 458. 459. 462. 464. 465. 466. 467. 468. 469. 470. 471. 472. 473. 474. 475. 476. 477. 479. 480. 481. 482. 483. 484. 485. Power Requirements of Electrically .Driven Dairy Manufacturing Equip- ment. The Problem of Securing Closer Rela- tionship between Agricultural Devel- opment and Irrigation Construction. I. The Kadota Fig. II. The Kadota Fig Products. The Digestibility of Certain Fruit By- Products as Determined for Rumi- nants. Part II. Dried Pineapple Pulp, Dried Lemon Pulp, and Dried Olive Pulp. The Feeding Value of Raisins and Dairy By-Products for Growing and Fattening Swine. Economic Aspects of the Apple In- dustry. The Asparagus Industry in California. A Method of Determining the Clean Weights of Individual Fleeces of Wo»l. Farmers' Purchase Agreement for Deep Well Pumps. Economic Aspects of the Watermelon Industry. Irrigation Investigations with Field Crops at Davis, and at Delhi, Cali- fornia, 1909-1925. Economic Aspects of the Pear Industry. Rice Experiments in Sacramento Val- ley, 1922-1927. Reclamation of the Fresno Type of Black-Alkali Soil. Yield, Stand and Volume Tables for Red Fir in California. Factors Influencing Percentage Calf Crop in Range Herds. Economic Aspects of the Fresh Plum Industry. Prune Supply and Price Situation. Drainage in the Sacramento Valley Rice Fields. Curly Top Symptoms of the Sugar Beet. The Continuous Can Washer for Dairy Plants. Oat Varieties in California. Sterilization of Dairy Utensils with Humidified Hot Air. The Solar Heater. Maturity Standards for Harvesting Bartlett Pears for Eastern Shipment. The Use of Sulfur Dioxide in Shipping Grapes. Adobe Construction. Economic Aspects of the Sheep In- dustry. Factors Affecting the Cost of Tractor Logging in the California Pine Region. Walnut Supply and Price Situation. Poultry Houses and Equipment. Improved Methods of Harvesting Grain Sorghum. I. Irrigation Experiments with Peaches in California. II. Canning Quality of Irrigated Peaches. The Use, Value, and Cost of Credit in Agriculture. Utilization of Wild Oat Hay for Fat- tening Yearling Steers. Substitutes for Wooden Breakpins. Utilization of Surplus Prunes. The Effects of Desiccating Winds on Citrus Trees. Drying Cut Fruits. BULLETINS— (Continued) No. 486. Pullorum Disease (Bacillary White Diarrhea of Chickens). 487. Asparagus (Series on California Crops and Prices). 488. Cherries (Series on California Crops and Prices). 489. Irrigation Water Requirement Studies of Citrus and Avocado Trees in San Diego County, California, 1926 and 1927. 490. Olive Thinning and Other Means of Increasing Size of Olives. 491. Yield, Stand, and Volume Tables for Douglas Fir in California. 492. Berry Thinning of Grapes. 493. Fruit Markets in Eastern Asia. 494. Infectious Bronchitis in Fowls. 495. Milk Cooling on California Dairy Farms. 496. Precooling of Fresh Fruits and Tem- peratures of Refrigerator Cars and Warehouse Rooms. No. 497. 498. 499. 500. 501. 502. 503. 504. 505. 506. 507. 508. 509. A Study of the Shipment of Fresh Fruits and Vegetables to the Far East. Pickling Green Olives. Air Cleaners for Motor Vehicles. Dehydration of Grapes. Marketing California Apples. Wheat (Series on California Crops and Prices). St. Johnswort on Range Lands of California. Economic Problems of California Agri- culture. (A Report to the Governor of California.) The Snowy Tree Cricket and Other Insects Injurious to Raspberries. Fruit Spoilage Disease of Figs. Cantaloupe Powdery Mildew in the Imperial Valley. The Swelling of Canned Prunes. The Biological Control of Mealybugs Attacking Citrus. CIRCULARS No. No. 115. Grafting Vinifera Vineyards. 279. 127. House Fumigation. 178. The Packing of Apples in California. 282. 212. Salvaging Rain-Damaged Prunes. 230. Testing Milk, Cream, and Skim Milk 288. for Butterfat. 290. 232. Harvesting and Handling California 292. Cherries for Eastern Shipment. 294. 239. Harvesting and Handling Apricots and 296. Plums for Eastern Shipment. 240. Harvesting and Handling California 301. Pears for Eastern Shipment. 304. 241. Harvesting and Handling California 305. Peaches for Eastern Shipment. 307. 244. Central Wire Bracing for Fruit Trees. 308. 245. Vine Pruning Systems. 310. 248. Some Common Errors in Vine Pruning and Their Remedies. 311. 249. Replacing Missing Vines. 312. 253. Vineyard Plans. 257. The Small-Seeded Horse Bean (Vicia faba var. minor). 316. 258. Thinning Deciduous Fruits. 259. Pear By-Products. 317. 261. Sewing Grain Sacks. 262. Cabbage Production in California. 318. 265. Plant Disease and Pest Control. 319. 266. Analyzing the Citrus Orchard by Means 320. of Simple Tree Records. 269. An Orchard Brush Burner. 321. 270. A Farm Septic Tank. 276. Home Canning. 278. Olive Pickling in Mediterranean Countries. The Preparation and Refining of Olive Oil in Southern Europe. Prevention of Insect Attack on Stored Grain. Phylloxera Resistant Vineyards. The Tangier Pea. Alkali Soils. Propagation of Deciduous Fruits. Control of the California Ground Squirrel. Buckeye Poisoning of the Honey Bee. Drainage on the Farm. Liming the Soil. American Foulbrood and Its Control. Cantaloupe Production in California. The Operation of the Bacteriological Laboratory for Dairy Plants. The Improvement of Quality in Figs. Principles Governing the Choice, Oper- ation, and Care of Small Irrigation Pumping Plants. Electrical Statistics for California Farms. Fertilizer Problems and Analysis of Soils in California. Termites and Termite Damage. Pasteurizing Milk for Calf Feeding. Preservation of Fruits and Vegetables by Freezing Storage. Treatment of Lime-induced Chlorosis with Iron Salts. 13ih-10,