^Aavaan-i^ THE MONTHLY BULLETIN CALIFORNIA STATE DEPARTMENT OF AGRICULTURE Volume IX AUGUST, 1920 No. 8 Special Pest Control Issue SACRAMENTO, CALIFORNIA CONTENTS. Pane THE PUNCTURE VINE (Tribulus terrestris) COVER THE BLACK-SCALE PARASITE, Aphycus lounsburyi FRONTISPIECE MAKING A PURE SEED LAW EFFECTIVE G. H. HECKE__ 305 "TERRESTRIAL TRIBULATION" G. H. HECKE__ 306 IMPORTANCE OF CALIFORNIA AS A BOXED APPLE PRODUCING STATE F. W. READ 307 COMING EVENTS CAST THEIR SHADOWS BEFORE D. B. MACKIE__ 309 THE LIFE HISTORY AND INTRODUCTION INTO CALIFORNIA OF THE BLACK-SCALE PARASITE, Aphycus lounsburyi HOW : HARRY S. SMITH AND HAROLD COMPERE 310 THE APPLICATION OF VACUUM FUMIGATION TO FRESH AND PACKED DATES D. B. MACKIE__ 321 MISCELLANEOUS INSECT AND FUNGOUS DISEASES NEWLY REPORTED FROM HAWAII HAW. AGR. EXP. STATION__ 325 A TERMITE PEST OF VINEYARDS R. L. NOUGARET__ 327 THE SPREAD OF THE PUNCTURE VINE IN CALIFORNIA ETHELBERT JOHNSON 330 ARGENTINE ANT CONTROL FROM AN ECONOMIC STANDPOINT A. F. SWAIN__ 333 THE DANGER OF INDISCRIMINATE INTRODUCTION OF FOREIGN PLANT VARIETIES I. WILKANSKT__ 339 A RECENTLY DISCOVERED CITRUS PEST IN CALIFORNIA : R. S. WOGLUM 341 SEED PRODUCTION OF THE CANADA THISTLE IN SOUTHERN CALIFORNIA ETHELBERT JOHNSON__ 343 BEAN WEEVILS IN CALIFORNIA ANDREW LARSEN 344 PLANT QUARANTINE SERVICE: REPORT FOR JUNE, 1920 FREDERICK MASKEW 350 Si s I * r O '60 THE MONTHLY BULLETIN DEPARTMENT OF AGRICULTURE STATE OF CALIFORNIA DEVOTED TO AGRICULTURE IN ITS BROADEST SENSE, WITH SPECIAL REFERENCE TO PLANT DISEASES, INSECT PESTS, AND THEIR CONTROL. to Sent free to all citizens of the State of California. Offered In exchange for bulletins C-~y of the Federal Government and experiment stations, entomological and mycological r..-> journals, agricultural and horticultural papers, botanical, biological and other pub- ^ - lications of a similar nature. G. H. HKCKE, Director Censor C\j BRONTE A. REYNOLDS, Assistant Secretary Editor Entered as second-class matter October 6, 1919, at the post office at Sacramento. California, under the act of June 6, 1900. AUGUST, 1920 No. MAKING A PURE SEED LAW EFFECTIVE. Regardless of the expected legislation bearing upon the important tn question of pure seeds, it is evident that we must view the matter from o| certain angles, which may be affected only indirectly by any regulations or code of procedure. ^ The most potent and far-reaching factors having direct bearing upon ^ this important issue of clean, high-quality seeds are essentially educa- o tional and any good results to be had through .the enactment of pertinent laws must of necessity be influenced in a great degree by the care that has been employed in preparing both the consumer and the producer to meet the conditions which will be brought into action by fel such needed legislation. ff California at present has no pure seed law. Such meritorious legis- jj lation, however, has been in effect in other states for some time and J notwithstanding the faults and flaws that invariably crop out when 3 new codes and regulations are substituted for the old order, the 8 cumulative benefits to be had under the operation of such laws are readily appreciated and improvement as affecting their efficiency is < only a matter of time and progressive education work. The great advantages to be enjoyed by a given state from the enact- ment of pure seed legislation must accrue as well from other sources than those merely having to do with seed inspection and seed- testing. The farmer must of necessity be taught that poor seed is dear at any price. Under such conditions the dealers, being confronted by more critical buyers who decline to use cheap, and inferior seeds, will discontinue or discourage the sale of any but a better grade, produced under favorable conditions and ^naranlced as to germination and freedom from exces- sive admixtures of noxious weed seed. Any seed laws which may be placed on the statute books in a given slate will have for their primary object the improvement of the quality '59916 306 THE MONTHLY BULLETIN. of agricultural seeds, but to realize the greatest benefits to all con- cerned we must revert to the source of much of the past difficulty and apply certain remedial measures on the farms where the seeds are produced. The seed grower should understand that clean seeds reasonably free of weed seeds in the end are a matter of dollars and cents to him, and that the reputation of his business will receive the greatest stimulus through the exploitation of a guaranteed product, exceeding in fact the returns from any other known source of advertising. As an index to the great injury that misrepresentation can work a given seed house, we will cite the following : A lot of seed (sample X) was purchased for alsike and timothy mixture. Analysis showed it to contain 28 different kinds of weed seeds amounting to nearly 12 per cent by weight. This seed was shipped by a middle-western seed house that was guilty of many other infractions of the laws of common honesty. In the absence of a federal law it may not be possible for the state to hold up interstate shipments such as these, but we may rest assured that but few hard-headed, thinking farmers will go back to that seed firm when they want more alsike and timothy. Thus we may see that the efficacy of any so-called seed laws that may be established depends in a large measure upon the consistent observance of many related factors which may not for purely mechani- cal reasons be adequately covered by the law as written. To this end, then, we should have : (1) A wider, common knowledge of weeds and approved methods of control and eradication to be taught in the schools and agitated by the press through newspapers and farm journals. (2) The earnest cooperation of farmers, seed dealers and seed pro- ducers in California, making for the establishment of standardized grades of approved strains and varieties grown and stored in California under favorable conditions. (3) A radical departure from the over-colored extravagant style of advertising so-called phenomenal varieties to be replaced by a plain, honest, descriptive statement as to variety, merits, etc. (G. II. H.) "TERRESTRIAL TRIBULATION." With the waning of the 1920 summer season, the Department of Agriculture is beset with queries, protests and anxious ones, who want to know what to do about the novel and pernicious weed pest that is playing havoc with their automobile tires, and one which, from present indications, bids fair to rank as a first-class dangerous plant pest. The offender is the "puncture vine" (Tribulus terrestris), late of the Sahara Desert and recorded by Pliny and others of the elder historians, and "running true to name" it does puncture! This weed produces numerous prostrate runners which at frequent intervals bear burs consisting of clusters of five spiny nutlets. At maturity the nutlets fall apart, always with one spine pointing upward. By way of explanation, it should be noted that California is the land of "out-of-doors" and recent statistics show that "one of every THE MONTHLY BULLETIN. 307 seven" in the state operates an automobile. Also it is notable in pass- ing that the state is linked up by splendid highways, north, south, east, and west, making nearly every section easily and quickly available by motor, which fact commercially has aided greatly in marketing perish- able fruits and vegetables in times of car shortage. Now comes this Saharan weed, which while not having honorable mention among the Biblical "Plagues of Egypt," surely ranks first as an enemy of automobile tires in California. One outstanding feature of its dangerous character lies in the fact that, while classed as a plant fostered and nourished by arid desert conditions, it readily adapts itself and thrives in the warm, rich valley lands of our state wherever it has located. A good idea of the wide damage to be accomplished by this pest may be had from the recently completed survey, which shows it to be more or less widely distributed from Red Bluff on the north, through the Sacramento, San Joaquin, Antelope and Imperial valleys, to the Mexican border on the south, which constitutes in fact the main motor artery of the state. Few automobile tires are proof against its barbs; no bicycle tire is immune to injury; and horses and live stock have suffered serious injury as a result of contact with it. Although at this date the range of this weed has been rapidly extended, it is possible still, by properly supported action and concerted interest, to inaugurate a system for the eradication of this new pest, one of the most unique in the introduced plant history of the state. (G. H. H.) THE IMPORTANCE OF CALIFORNIA AS A BOXED APPLE PRODUCING STATE. Few people realize the importance of California as a boxed apple state. Of the total number of ears shipped in 1919, California ranked second, the State of Washington being the only one in the Union to exceed it. According to figures recently released by the Federal Bureau of Markets, California was followed in the number of cars shipped in 1919 by Oregon, Idaho and Colorado in the order named. From the State of Washington, the most important boxed apple state in the union, 19,760 cars of apples were shipped in 1919, and of this number 2257 cars were taken by New York City and 1366 by Chicago. The Bureau of Markets, over a period of years, has been compiling the number of carloads of the principal fruits and vegetables unloaded at the large market centers of the country. This information is very valuable as indicative of the consuming capacity of the larger terminal markets. The figures show that California shipped 4147 cars in 1919 and of that number 539 cars were unloaded at New York City, or about 76 per cent of the California apples unloaded at the ten principal market centers of the United States. It would seem, therefore, that NV\v York is by far the most important outlet for California stock. Chicago received 66 cars of California apples in the same year, Cin- cinnati 31, St. Louis 24, Philadelphia 21, Pittsburgh 16, and Kansas City 12. 308 THE MONTHLY BULLETIN. The following table abstracted from the Market Keporter of the Bureau of Markets, under date of June 5, 1920, gives a very accurate idea of the competition met by California apples from the other boxed apple states: CARLOADS OF APPLES UNLOADED AT TEN LARGE CITIES. Unloads by States of Origin for Four Years. Originating state New York Philadelphia Pittsburgh 1919 1918 1917 1916 1919 1918 1917 1916 1919 1918 1917 1916 Boxed- Apples. 83 2 187 2,257 870 11 3,949 23 5 64 2,243 561 124 2 3,012 1 3 110 1,170 290 147 1,721 6 45 1,010 171 150 1,382 1 C 1 d 14 3 a 32 55 53 225 450 125 20 33 9 18 10 3 1 ! 308 546 193 a 99 Idaho 62 645 54 21 3 785 , 139 234 3 2 j 5 o ; o 144 239 3 334 3 3 343 Washington California All othr Totals - - - - Originating State Washington Cincinnati 1919 1918 1917 1916 1919 1918 1917 1918 Boxed Apples. Montana ._ ,.. ..... | Idaho 1 156 28 2 157 31 11 C 41 5 61 132 ^ 137 20 1C4 79 Washington .... California 31 18 242 8 4 18o 3 ; , 2 127 81 All othr 1 188 j 190 94 46 Totals Originating state 1919 162 22 10 242 1,366 65 2 1,953 Chicago ' St. Louis Kansas City 1918 41 16 69 490 26 27 L 639 1917 107 6 17 163 785 52 116 2 1,251 1916 1919 1918 j 1917 1316 1919 1918 1917 1916 31 Boxed Apples Colorado . ._ 95 8 1 10 676 33 39 1 79 180 36 6 44 40 1M New Mexico Utah . .. .. 80 17 24 264 14 28 162 6 12 1 889 6 1S8 150 56 4 1 391 2 133 6 8 1 156 1 73 238 12 12 1 381 23 265 11 12 355 4 4!) 188 1 2 38 r 8 280 6 17 3 34f> Idaho .. Washington Oregon .. .. California All other Totals THE MONTHLY BULLETIN. 309 Originating State Minneapolis St. Paul 1919 4 1918 10 1917 . 1 1916 4 1919 1918 1917 1916 Boxed Apples. Colorado Utah | Idaho - - 5 142 2 4 153 5 211 2 2 220 7 97 30 134 8 214 12 6 240 Washington -- . -- - ... .. 145 1 1 4 160 4 ! 183 5 57 12 258 158 10 172 Oregon --. - - _ _ All othr Total* - -. -- -- 155 176 California is a more important apple state so far as volume is con- cerned than is Oregon, Idaho, or Colorado. This fact emphasizes the importance of proper standardization work. If our stock is going to meet the sharp competition from other states, it is essential that apples moving out of California be graded strictly according to the California standardization law, and that every car maintain the reputation of this state for quality, grade and pack. That California will continue to be a very important factor in the shipment of boxed apples, is indicated by the statistics covering the nonbearing acreage in the state. Figures compiled by the California Development Board show that there were 690,835 nonbearing trees in San Bernardino County alone in 1919, which is more than the total number of bearing and m. lib-firing trees in Santa Cruz County for the same year. These figures may be taken as indicative of the nonbearing acreage in the southern California districts. Uniform enforcement of the apple standardisation law will prove beneficial to the industry, and assist in obtaining fair prices for the large crops which are bound to come in ensuing seasons. (F. W. R.) COMING EVENTS CAST THEIR SHADOWS BEFORE. The successful application of vacuum fumigation to the control of insects affecting food products marks a step forward in matters of pest control. While as yet the field of its possibilities is practically untouched, a list of the products which lend themselves to treatment by this method covers such a broad range that an attempt to name them would in all probability place one in the ranks of a false prophet. In view <>f the foregoing it is sufficient 1<> say that the question as to uum fumigation the field of food products imiir years will answer. (D.B.M.) THE MONTHLY BULLETIN CALIFORNIA STATE DEPARTMENT OF AGRICULTURE Vol. IX - AUGUST, 1920 THE LIFE-HISTORY AND SUCCESSFUL INTRODUCTION INTO CALIFORNIA OF THE BLACK SCALE PARASITE, APHYCUS LOUNSBURYI HOW. 1 By HARRY S. SMITH* and HAROLD COMPERED INTRODUCING THE PARASITE IN CALIFORNIA. The black scale (Saissetia oleae Bern.) which holds first rank as an insect pest in California, is a good subject for control by the biological or "parasite" method. To our knowledge, more than thirty species of insects are recorded as preying upon this pest in various parts of the world. While some of these parasitic and predaceous insects are of great value, others are not of much economic importance and their introduction into California would prove of little benefit. Professor Charles P. Lounsbury, government entomologist for the Union of South Africa, states in a letter under date of March 30, 1912: "As I have written before, I am firmly convinced that the black scale is held down in South Africa entirely through the influence of parasites. Its abun- dance on the material collected for dispatch to California is due merely to the local prevalence of the Argentine ant." It is evident from observations in the past, that no single parasite or predator controls the black scale; instead there are combinations of the different forms, which by concerted action dominate the pest in given localities. To introduce the most effective species which do not occur in California, and then to make them attain their greatest efficiency by rearing and distributing them in large numbers is one of the undertakings of the Pest Control Service of the California State Department of Agriculture. For several years the Commission of Horticulture, now the State Department of Agriculture, has been attempting to establish in Cali- fornia, additional natural enemies of the black scale. In this work we have continually had the active assistance of Dr. C. P. Lounsbury and C. W. Mally, entomologists for the Union of South Africa, to whom we are greatly indebted. In the summer of 1912 mention was made of rearing two hundred of what was supposedly Aphycus loimsburyi from material received from South Africa. It is now believed that this was a case of mistaken identity, another parasite being recorded under this name. In 1914, however, a shipment of black-scale material was received from Messrs. Lounsbury and Mally, from which we succeeded 'The life-history investigations recorded in this paper are the result of Mr. Compere's labors. (H. S. S.) 2 Entomologist, Pest Control Service, California Department of Agriculture, Sacra- mento, Cal. 'Assistant, Pest Control Service, California Department of Agriculture, Alharnbra, Cal. Tin; MONTHLY BULLETIN. 311 312 THE MONTHLY BULLETIN. in rearing a few specimens of what was unquestionably this species. The material was collected at Wynberg and Sea Point near Cape Town, and from the gardens of Cape Town itself. THE PARASITES DETERMINED. In 1914 some of these parasites were sent to P. H. Timberlake for an authentic determination. He replied that the parasites were undoubt- edly Aphycus lounsburyi Howard, although fully twice as large as the types. The following is transcribed from his letter : ' ' There is a series in the U. S. National Museum which I examined last winter and thought at first they might be distinct on account of the twice larger size, slightly exserted ovipositor, and of the ocelli being in an equilateral instead of a strongly acute triangle. The ovipositor is not exserted in the types, but they are very small specimens and wretchedly pre- served. Your specimens are intermediate as the ocelli are in an acute triangle. On account of the evident variation in this species, I hope you are in a position to preserve a good series showing such variations as I have indicated. Coloration, however, is remarkably uniform. ' ' Owing to the fewness in numbers of this parasite in the above- mentioned shipment, however, we did not succeed in establishing the parasite in the open, and it was not until we reared this same species in some numbers from material collected by the late E. J. Vosler in Australia, and applied to its propagation the recently developed method of growing the black scale on potato sprouts, that we were successful in firmly establishing Aphycus lounsburyi in the citrus orchards of California. DESCRIPTIONS OF APHYCUS LOUNSBURYI. The Adult. The adult of Aphycus lounsburyi is very fantastically marked as is strikingly shown in the frontispiece. For a detailed technical descrip- tion a portion of P. H. Timberlake 's work is herewith given. 1 Female Front and vertex apparently (being much shrunken in cotypes) nearly three times as long as wide; ocelli in an acute-angled triangle, the posterior pair close to the eye margin : untennal scrobes broad and shallow ; eyes nearly non- pubescent. Antennal scape about one-third as wide as long, widest just beyond the middle ; pedicel as long as the first three funicle joints combined ; first four funicle joints of nearly equal length, wider than long and hardly increasing in width, last two joints considerably longer and wider, the sixth a trifle longer than the fifth, both a little wider than long; club oval, rounded ;,t apex, about one-third- wider than the preceding joint and a little longer than the last four funicle joints combined. Wings uniformly ciliated; th:.- oblique hairless streak but little wider below, interrupted, the cut-off portion separated from ih' basal hairless streak on the posterior margin of the wing. Length: 0.7 mm. Front and vertex bright orange yello\\ : fatv. cheeks, and under parts pale yellowish; mesonotum dusky orange-yellow: concealed part of the occiput and the prouotum, the metanotum, propodfiiin. and dorsum of abdomen brown; collar of pronotum and tegulae sordid whitish; th- former with a minute, blackish dot on each corner, the latter witlr the posterior margin pale brown. Antennal scape black with a very narrow line en upper margin, th;* apex and a broad band on the basal third of the lower mar-in white: base of pedicel, first four funicle joints and club black; apical two-thirds of p;-dir.>l. last two funicle J *r TO : ^ S. Nat. Mus. Vol. 50, page 610. "Revision of the Genus Aphycus." P. H. Timberlake. THE MONTHLY BULLETIN. 3l3 joinis and some! imes the underside of the third and fourth joints white. Legs pale yellowish; middle tibia- with a pair of distinct, brown dots near base, another pair at the middle, and a narrow, brown annulus at: the apex; hind tibiae similar, but the markings fainter; front tibia* with the apical annulus faint and the two pair of dots replaced by a large but faint brownish blotch on the anterior or upper surface ; last joint of the tarsi faintly blackish. Wings hyaline, the veins pale yellowish. | Bedescribed from three females (cotypes) in poor condition, reared from Siiis.wtia oleae (Bernard), Cape Town, South Africa (C. P. Louns- Imry). The fourth cotype has been lost by dropping from the card point.] "The following material also examined: Seven females, one male reared from the same host, Cape Colony, South Africa (C. P. Lounsbury), and two females from the same host and locality (through II. S. Smith), California State Insectary No. 655cp. The females differ from the types as follows: !'< male Front and vertex varying from twice to nearly two and one-half times as lonir ;,s wide; ocelli in an equilateral triangle, or nearly so, but in three specimens in more or less acute-angled triangle, the posterior pair about one-fourth their own diameter from eye margin. Ovipositor protruded about one-tenth the length of abdomen. Coloration nearly as in types but the front, vertex, and mesonotum uniformly dark orange-yellow, but the dark parts nearly black instead of brown; dors-urn of abdomen with the lateral margins narrowly whitish posterior to the vibrissa? half way to the apex, and the anterior corners of the basal tergites invaded by the whitish of the venter; tibial bands and dots heavier and blackish and with an additional dot at the knee joint. Length : 1.4 mm. l//c Front and vertex a little less than twice as long as wide; ocelli in an equilateral triangle. Antennal scape narrower than in the female and the club smaller or no longer than the last three funicle joints combined. Wings as in the female, but the cut-off portion of the oblique hairless streak larger and con- nictinu with a branch of the basal hairless streak on the posterior border of wing. Length : l.o mm." LIFE HISTORY NOTES. Habits of Adult. The adult parasites escape from circular exit holes cut through the d(.rsal region of the shell. Cutting the shell of the older scales is a slow and laborious process. The parasites effect a small hole through the shell by biting out tiny pieces with their sharp-pointed mandibles. After a hole is cut, it is slowly enlarged by cutting around the edges. When the exits are large enough to permit escape the parasites force themselves out of the old shells. The adults are very quick and active. AYhon an attempt is made to catch them they dodge to the underside of the twigs or hide behind the leaves, something after the manner of a squirrel in a forest which attempts to hide on the approach of an enemy. The adults do not readily take to flight but depend on their agility to escape. Although very active and shy at the approach of an enemy, AI>IIIICUX is a very satisfactory parasite to bundle in confinement. Individuals confined in viaU with sugar and water and kept in a cold place, where oviposition was prevented, lived over six weeks before they were liberated on 314 THE MONTHLY BULLETIN. infested twigs. When confined in vials, the parasites need not be nursed like some of the more delicate insects. They do not easily become entangled in the syrup, and only an occasional freshening of the water is necessary. In the field A. lounsburyi does not have a tendency to spread very rapidly and must be aided by man, a trait which we consider to be greatly in its favor. The parasites usually confine their activities to the individual trees in which they are liberated, providing there is a supply of scale suitable for oviposition. In many cases they will haunt the particular limb on which they are first established. Unlike some parasites, this species is particularly thorough in its work; if in sufficient numbers it will parasitize practically every scale in the area of its abundance. This parasite will develop in any black scale containing sufficient nourishment to bring a single larva to maturity. It can commence work on the small scales, beginning about the time the raised "H" is readily discernible, and continues to multiply at the expense of the pest, until the bodies of the parent scale have shriv- eled, after their eggs are laid. This is a very decided advantage, for it enables the parasite to propagate, step- ping up its abundance uninterruptedly for almost the entire life of the host, which is normally one year. In con- trast with this, there are internal para- sites of the black scale which can con- tinue their activities for only a very limited period, because the scale in its FIG. 83. A. lounsburyi: Egg.be- growth forms physical characteristics p o r s?tio ( n? P iateTai SS^JSBUS which render ** invulnerable to the at- tack of certain species. When there is an opportunity for a choice, Aphycus lounsburyi will select the larger scales in preference to the smaller ones for oviposition. To a certain extent this also is a decided advantage, for it then first eliminates the scales which are likely to be early egg-bearers, thus prolonging the period in which it can do effective work. After the scales commence egg-laying this trait of selecting the older individuals works to a disadvantage; it disrupts the host and checks egg-laying, but the effects of the parasitism do not prevent the scale eggs which have already been deposited from hatching, thus providing for a partial new generation to reinfest the trees. The effectiveness of this parasite can not be judged merely by the number of exit holes showing in the scale. At times the older egg-bearing scale will be parasitized to an enormous extent; but the effect on the pest may be slight, owing to the fact that a hatch will occur from the eggs already deposited, despite the fact that the parent scales have been destroyed. This, however, may work to its advantage in another way, since it provides numerous parasites for the following generation of scales. The work of this parasite is characteristic and easily distinguished. In the advanced stages of parasitism the scales become bloated, which somewhat effaces the raised " H " and their color becomes a light amber. If the scales are lifted from the twigs, the ventral tissue is seen to be taut, membraneous and somewhat translucent. The exit holes are THE MONTHLY BULLETIN. 315 smaller than are those of Scutellista and usually there are two or more to each scale. In the case of A. lounsburyi the exit holes only penetrate the body cavity of the scale, while in the case of Scutellista cyanea Motsch. the exit holes penetrate into the egg cavity. As is well known, many species of insects, and particularly parasitic Hymenoptera, are parthenogenetic, i. e., the eggs of the unfertilized females will produce offspring. Most insects which reproduce in this way have progeny confined to one sex only, that is, they are either all male or all female. In the case of Aphycus laun-sburyi only females are produced when the parent female is unfertilized. On the other hand, if the female becomes fertilized the progeny is composed of a proportion of males. If the species does not weaken by parthenoge- netic reproduction, it would be a decided advantage if only the females are colonized, thus only increasing the individuals which are capable of reproduction. Observations extending over a long period of time, how- ever, would be necessary in order to determine whether or not the colonization of only the females would prove to be advantageous. Cam- eron, who has made extensive studies in parthenogenesis, thinks that this mode of reproduction involves a constitutional weakness, fewer of the parthenogenetic young reaching maturity. This, he suggests, may be compensated for when the parthenogenetic progency are all of the female sex, by the fact that all those which grow up are producers of eggs. D. Sharpe 1 after a review of the problem concludes: "It appears most probable that parthenogenesis and the special sex produced by it, whether male or female, are due to physiological con- ditions of which we know little, and that the species continue in spite of parthenogenesis, rather than profit by it. ' ' The studies of P. H. Timberlake on the subject of parthenogenetic reproduction of the Encyrtidae found in Hawaii is very pertinent. The following quotation is from his work 2 : "Parthenogenesis has also played a large part without much doubt in helping the establishment of certain of our immigrant species. As a general rule it may be stated quite confidently that all Encyrtidae and for that matter most, if not all, Chalcidoidea, in so far as their habits have been investigated, are able to reproduce parthenogenetically under stress of necessity. Probably most species of Encyrtidae produce only males when the reproduction is parthenogenetic, and in case of the usual method of reproduction they reproduce in different species a variable proportion of both males and females. Before studying the habits of our local species, I had never verified the existence of any other method of reproduction among the Encyrtidae, and was surprised to find that certain of our species are regularly thelyotokus (i.e. produce only females) in reproduction. In Adelencyrtus odonaspidis, Blep- yrus mexicanus, Encyrtus infelix, Pauridia peregrina, and Saronotum americanum, thelyotoky is the regular means of reproduction and males are rarely produced, being in fact entirely unknown in the case of Adelencyrtus and Saronotum. I have reared Pauridia through many generations without finding any males, and have in fact seen but a 'Insects: D. Sharpe. Pt. 1, p. 517. "Proc. Haw. Entom. Soc., 1918, p. 195. 316 THE MONTHLY BULLETIN. single male, reared by E. M. Ehrhorn several years ago. I have like- wise reared Blepyrux through several generations and was able to find males of this species only by examining some vines at the sugar planters' experiment station [Hawaii] at a time when both host and parasite were unusually abundant. Of Encyrtus infelix, I was fortunate enough to rear a single male in a small series obtained in 1916, and this is the only male specimen that I have seen out of the numerous specimens examined from all parts of the world. Miss A. L. Embleton in her work on this species states that the males are exceedingly rare, only one occurring to about a thousand females. The existence of this habit of thelyotoky is obviously a great advantage to a species invading a new region, since it might become established under favorable conditions from a few females or from a single specimen. Conversely the arrheno- tokous (i.e. producing males only) habit of reproduction may act disad- vantageously before a species is well established, since the rapid dis- persal which usually takes place will tend to increase the difficulties of the sexes finding each other, and thus restrict the necessary fertili- zation of the female." In the case of Alphycus lounsburyi it was decided not to try to alter the usual mode of reproduction and both males and females were liberated. This has not affected the abundance of the parasites to any great extent, the males being very rarely met with in the orchards. We have never even observed a pair mating. Oviposition. This parasite gains its superiority by means of its singular method of attack, which enables it to overcome the protecting characteristics of the scale, and by means of the larval habits which permit its develop- ment in scale showing a wide variation in size. The method of attack is specialized so as to avoid the work of penetrating the tough leathery derm of the scale. The long flexible ovipositor is extended underneath the scale, and then curved upward so as to penetrate the soft ventral tissue. There is very little work prior to the insertion of the ovipositor, the female only tapping the scale with her rapidly-vibrating antennae. The lateral margins around the rim of the scale are the points selected for the insertion of the ovipositor. When oviposition occurs, the para- site stands facing away from the scale, with the ovopositor extended underneath the rim and then curved upward so as to penetrate the soft tissue. The act is usually complete within thirty seconds and the parasite withdraws. In one scale an individual will deposit from one to twelve or more eggs, depending on the size of the host. By gluing scales to cover glasses, and then turning the glasses upside down over a cell containing a parasite, it is possible to observe the act of oviposition in detail under a binocular microscope. A strong light will render the ovipositor and abdomen of the parasite transparent, and the interior of the scale will be rendered partly visible, so that the whole perform- ance can be viewed. When the egg is forced from the uterus into the ovipositor it is compressed to a long cylindrical form so as to pass through the channel in the long slender ovipositor. The egg is hardly recognizable as it passes through the ovipositor, for so rapid and even is the movement that it looks more like a flow of quicksilver than the THE MONTHLY BULLETIN. 317 passage of an egg. The forepart of the egg, which still retains its cylindrical form, acts like a probe to penetrate some distance beyond tiif tip of the ovipositor into the body of the scale. Suddenly the liquid contents of the egg rush forward, inflating the anterior portion, which rises like a miniature balloon being inflated. The hind section of the egg remains tube-shaped after the contents have rushed forward. The parasite then withdraws the ovipositor, leaving the tube moulded in position, suporting the bulb or main body at one end, and the other end of the tube projecting through the integument of the host into the outer air. "When the parasite withdraws the ovipositor, just as the end of the stalk issues, it gives several vicious jabs with the oviposi- tor. This may prove to be the means by which the end of the stalk is punctured so as to make an opening for the admittance of air. The Egg. The newly deposited egg is stalked (fig. 83), the bulb is elongate oval, translucent white, and with a smooth shining surface. The bulb iiir;isiires .2 mm. in length, and the greatest width .08 mm. A ventral ril> or stay extends about two-thirds the length of the bulb. The rib appears to be a prolongation of the stalk. This rib serves as a stay which gives rigidity when the bulb is being inflated. Immediately after deposition the stalk becomes dense white. Later when the larva hatches the stalk seems to function as an air line, and it then becomes chitinized and dark colored. The rib enters into the construction of the anal shield which forms with the larva. The ovarian egg is quite different in appearance from the laid egg. It is a double-bodied affair, the two bulbs being divided by a long neck or constriction. The larger bulb is the main body which later contains the embryo. The smaller bulb or accessory body is an enlargement of the neck which serves as a reservoir to aid in the transformation that takes place during the passage of the egg through the ovipositor. The ovarian eggs of many parasites have an accessory bulb and con- necting neck which is not transformed into an air-line for the use of the larva?. It is supposed that this peculiar egg construction is for the purpose of making it possible to pass a comparatively large egg through a long slender ovipositor. The First-Stage Larva. Tin 1 newly-hatched larvae are found suspended in the body of the scale by means of a long stalk or air-line which penetrates the integu- ment of the host. Eggs and larvae can be located by the presence of the stalks, the tips of which project into the outer air. The larva is composed of thirteen segments, exclusive of the head; the five posterior segments being inclosed in an anal shield, which serves to hold the larva in intimate connection with the air-line. The average sized newly-hatched larva 1 measures .5 mm. in length, and the greatest width about .12 mm. The head is slighly narrower than the first seg- meut, the body being of nearly uniform width throughout. The skin is smooth, white, and translucent. The anal shield and stalk are living organisms in vital connection with the larva, as suggested to be the case in Microtcrys flavus, which was studied by Mr. Timberlake. In this 318 THE MONTHLY BULLETIN. stage two stigmata are discernible, situated on a prolongation of the two main tracheal trunks which places them in contact with the air-line. The two trunks are connected by transverse branches through the first FIG. 84. A. lounsburyi : First stage larva, lateral view, showing stalk, anal shield, and tracheal system. (Original.) and tenth segments. On the segments from two to ten inclusive, there arise from the trunks simple undivided branches, which extend dorsally and ventrally. Near the anterior end of the trunks simple branches extend into the head. Situated on the main tracheal trunks near the junctions of the branches on segments two, three, and four, the stigmal branches which appear in the second stage are beginning to form. The Second-Stage Larva. Aside from the increase in size, in this stage there is no great change in the general structure and habits of the larva. The respiratory system shows the most development, stigmata having formed on the second, third, and fourth segments; and the branches which arise from the main trunks having become so divided as to form many fine tracheae. The Third-Stage Larva. Larvae of the third stage show a marked change in their structure and habits. By this time the parasitic larvse have consumed the liquid contents of the scale, the interior of which now becomes a dry shell. FIQ. 85. A. lounsburyi: Mature larva, lateral aspect. (Original.) There is a change in the method of respiration, the larvae no longer need- ing to have the air piped into the scale, for now they can breathe air direct. The intimate connection with the air-line is severed, freeing the THE MONTHLY BULLETIN. 319 larvae which are now equipped with a well-developed trac-heal system. There is a wide variation in the size of the mature larvse. Measurements ranged from .3 mm. to 1.7 mm. in length, and from .6 mm. to .9 mm. in width. The body segments from 1 to 9 are larger and more distinct than are the succeeding four posterior segments which are not easily defined. The body tapers towards the head and rear. The contents of the alimentary canal fill almost the entire body cavity. The mandibles are stout with a broad base and brownish in color. On the main tracheal trunks, in addition to the dorsal and ventral branches on segments 2 to 10 inclusive, there are branches which extend to nine A F iounsburi i P airs ^ P e n stigmata. The dorsal and ventral, as well Mandible of ma- as the branches leading into the head, give rise to numer- Si as v p'ec a t~. ous fine tracheae The Pupa. The pupas which are found in the dried body cavity of the host appear to be naked, and as with the larva? they are occasionally found packed very tightly. At first they are white, later they take on the color pattern of the adult. Generations. The time from egg to adult will vary from twenty-eight days to three months, depending on climatic conditions. Under artificial con- ditions in the insectary, twenty-eight days was the minimum time for development, while in the field during the winter months this period will last for about three months. ESTABLISHING THE SPECIES IN CALIFORNIA. Iii the fall of 1919 at the Limoneira Ranch, Santa Paula, California, 53 lemon trees heavily infested with black scale were left unfumigated (through the cooperation of Messrs. Teague and Culbertson) in order to provide a propagating ground for Aphycus lounsburyi. The para- sites were first liberated in September. Liberations of Aphycus fol- lowed throughout the winter months. These liberations were later supplemented by colonizations of Scutellista cyanea and Rhizobius r< /ifrnlis in order to form a combination that would insure a natural control. The experiment proved satisfactory, and at this writing a new area comprising 10,000 trees has been set aside in an attempt to duplicate the performance on a commercial scale. In this demonstra- tion Aphycus lounsburyi accomplished more than did Scutellista cyanea and Rhizobius ventralis combined. However, the Aphycus was given the advantage both in the number of individuals liberated, and by making the liberations at an earlier period. In the city of Alhambra two other demonstration plots were selected ; one, comprising two and one-half acres set to oranges, and the other having 100 trees to the plot. In both of these plots the trees were heavily infested with black scale last fall. In these demonstration plots we were not able to make any quantity liberations until April. The results were not so satisfactory, as we were more than six months 320 THE MONTHLY BULLETIN. late in getting our insects in the field. This was due to the fact that the insectary was invaded by the predaceous mite, Pediculoidcs vcntri- cosus Newport, which forced us to destroy all of our material and make a new start. Apliycus is however now breeding abundantly in both orchards. To date about 30,000 Apkycus lountburyi have been liberated in our various demonstration plots. They have become acclimated and are rapidly increasing, thus adding to our fauna another beneficial insect. CONCLUSION. It is very possible that with the increase and spread of Aphycvs lounsburyi, setbacks will be encountered in the way of secondary parasites, or primaries that will adapt themselves to prey upon this species. Many newly-introduced parasites have been exploited as winners, and the disappointment which followed their failures is pro- verbial. Efforts should not cease how r ever until the black scale in Cali- fornia is controlled by its natural enemies, or the reasons for failure made clear. In the light of our present knowledge, the successful control of the black scale by the utilization of its natural enemies seems to be only a matter of time and work. If the beneficial insects which we now possess can not give the desired results in our fight against the scale, we can introduce other species from foreign lands. At this time w r e are engaged in trying to select the most effective exotic forms whose work will supplement that of the parasites we already possess. The black scale problem is a serious one. A single county in Cali- fornia is spending over three-quarters of a million dollars annually for fumigation, the major part of which is directed against this pest. If, as is hoped, control can be brought about by the biological method as was done in the case of the citrus mealybug, it will result in the saving of many hundreds of thousands of dollars annually to our California citrus growers. However, there should be no slackening in the present methods of handling the pest until the biological method of control is thoroughly demonstrated to be practical on a commercial scale. THE MONTHLY BULLETIN. 321 THE APPLICATION OF VACUUM FUMIGATION TO FRESH AND PACKED DATES. By D. B. MACKiE. 1 During the season of 1918 reports were sent to the State Department of Agriculture of heavy losses incurred in packed dates due to the inroads of certain storage insects, with the request that the office of pest control investigate the matter and endeavor to formulate measures that would give relief. In January, 1919, the writer was detailed to make a preliminary investigation and to report on the possibility of A VACUUM FUMIGATOR. FIG. 87. This vacuum fumigator was designed by the Pest Control Service of the California Department of Agriculture for the control of insects affecting dates. remedying conditions. In a conference the date growers pointed out that for some cause unknown to them the packed dates became infested and later, when in the channels of trade, would become so wormy that purchasers returned them in disgust, a condition which in turn caused merchants to decline to handle the product. Examination of infested packages showed Ihe dales to hi' heavily infested with the larvae of ike iiiioii dried fruit pest Plodia in-t<'ri>niicl< l/. Station Bull. 214, May. 1911. -Op. cit. 338 THE MONTHLY BULLETIN. effect on labor. It is true that the ants have no "sting" nor do they "bite" one, but it is rather annoying to have them crawling over one's face and hands and down his collar, and feeding on his lunch. And this is exactly what they do. To such men as pickers and pruners they are a very serious pest. Considerable loss is realized through the inef- ficiency of labor due to the presence of the ants both in lost time fighting them off, and in lost time breaking in new men to replace those who refuse to work under such conditions. A very conservative estimate of the loss of efficiency on this company's orchards is 15 per cent. That means if it takes 20 men 10 days to pick the fruit on a given block where the ants are not present, it will take over 11 days to pick; the same block if the ants are at all abundant. At $3 a day per man, this means an additional cost of about $70 a day. With a picking crew of 20 men working six months of the year, the additional cost for labor due to a loss of 15 per cent efficiency amounts to approximately $1,000. Add to this 20 more men working on the average of 200 days a year in various orchard operations, as hoeing weeds, irrigating, prun- ing, and so forth, and an additional cost of about $1,400 is realized. There is then a loss of about $2,400 a year due to the effect of the ants on labor. Ant control cost $1,400 and is good for at least two years and possibly three, which means a saving in the one item of labor alone of over $1,500 a year. Consequently if the relationship of the ants to the scale insects and mealybugs is not considered, the cost of treatment is more than warranted by the saving in labor costs. CONCLUSION. It has been demonstrated that the Argentine ant can be controlled under citrus orchard conditions in southern California, this costing less than 2^ per tree per year, possibly only 1J^ per tree per year. The ant is a prime factor in the Riverside district in the abundance of the soft brown scale and has necessitated the great expense of fumiga- tion, which is several times greater than the cost of ant control. It is also a prime factor in the abundance and spread of the Citrophilus mealybug, which is potentially a very serious orchard pest. The loss in efficiency of labor due to the ant is greater than the cost of ant control. THE MONTHLY BULLETIN. 339 THE DANGER OF INDISCRIMINATE INTRODUCTION OF FOREIGN PLANT VARIETIES. By I. WiLKANSKY, 1 Jerusalem, Palestine. The introduction of foreign varieties of plants used to be considered by our farmers in Palestine as a sign of progress and scientific manage- ment. Everybody tried to introduce something foreign, seldom stopping to consider whether it was worth while or whether the foreign was not inferior to the native variety. I am going to cite a few facts which will show how extremely cautious one has to be in introducing foreign varieties of plants. Our first European experts having rather naturally assumed a superior, disdainful attitude towards our native agriculture have also treated with contempt the native varieties which have grown in Pales- tine for thousands of years and have thoroughly adapted themselves to the local physical factors. One of their first acts was to introduce French varieties of olives, though we have had five good native varieties of oil producing olives. The Jewish farmers of Palestine saw something quite revolutionary about it the trees looked different and their fruit was large and they proceeded to imitate and grafted their trees to the new, imported varieties. But before the trees had come to bearing they were found to be infested with boring beetles (Bimatismus villosus and Phloeotri- lus olcae] and the olive fly (Bactrocera IDacus] oleae). Only the for- eign varieties were infested ; the native ones were free from these pests. The growers had to dehead trees as old as twenty years or more and regraft them to the native varieties. At present our Jewish olive growers carefully avoid taking grafting stock from our olive groves, in spite of the fact that our olive groves are much better than the groves of the native fellahin (peasants) for fear that they may stumble by mistake upon some imported, foreign stock. Grafting stock is therefore taken from the groves of the native fellahin in which only native varieties of the olive may be found. In the experimental farm, Ben Shemen, of which I have been in charge, I had the following happen to me. In my olive nursery I insisted upon using grafting stock derived exclusively from the famous olive forests of Lydda and Ramleh, in the foothills of Judea. The varieties of that district are called Rumi, hinting that they were planted by the Crusaders. Later however I discovered that a portion of the nursery was grafted with stock which was brought by a Jewish farmer from one of our colonies where French varieties of the olives were still grown. A grove was planted with stock from this nursery. Up to the bearing age of the trees nothing uncommon was observed in the growth of the trees, but on the eighth year, the olive fly broke out in the grove. Prior to this I never had observed the olive fly in Palestine. But I remembered it very well since a tour in Italy. There I saw hordes and hordes of flies covering the piles of olives gathered in their storehouses. In the restaurants when olives were served, my companion, an Italian 'Director of Agriculture of the Zionist Commisson, Jerusalem, Palestine. 340 THE MONTHLY BULLETIN. horticulturist, would cut the olives open to show me the galleries and labyrinths made by the fly in the meat of the olive. Olive after olive he would cut open and every one of them would invariably show these characteristic labyrinths. I knew that in Italy the olive fly was con- sidered one of the greatest pests known and that the best of Italian ento- mologists were devising means to combat it. Prof. Berlese was dis- tributing at that time in the olive groves of Italy baits of molasses and arsenic, placing the pots among the branches of the trees. And here I had the same "problem" before me. Was it possible that I failed to observe this pest in Palestine until it affected my own trees? I immediately proceeded to inspect carefully the old native groves located within a mile or so of the farm in my charge. Not on one tree grown on those thousands of acres have I discovered a trace of the pest. I showed olives affected with the fly to the owners of those groves no one of them had ever seen it before. I visited our Jewish colonies none of the trees grafted to native varieties was affected. Only in one small grove I found the olive fly. The owner wanted to produce a Provence variety and he did not graft his trees to a native variety. Nor do the boring insect Himatisms inllosus, Phloeotribus scarbc- oides and Hylesinus oleiperda attack the native Palestinian varieties, the wood of the native varieties being firm and hard while that of the French varieties is tender and soft. And if we compare the yields of the native varieties with those of the foreign ones, we shall see that they are inferior neither in quality nor in quantity. It is obvious, then, that in this case it was inadvisable to introduce foreign varieties. But even if the foreign varieties were superior, it is still very questionable whether it would pay to sacrifice the great resistance and peculiar adaptation of the native varieties for the sake of superiority in other respects. Therefore extreme vigilance and careful judgment should be exercised when it is proposed to introduce foreign varieties. In general it is best to leave the matter of introduction from foreign countries in the hands of specialists and experts on the staff of introduction gardens, they being best qualified to exercise all the vigilance and judgment required. THE MONTHLY BULLETIN. 341 A RECENTLY DISCOVERED CITRUS PEST, PLATYNOTA TINCTANA (WALK.) IN CALIFORNIA. L5y R. S. WOGIATM, U. S. Bureau of Entomology. INJURY TO ORANGES BY WORMS. Injury to oranges from short burrows in the rinds, frequently the forerunner of decay, is familiar to most packing-house managers and to many growers in southern California. These burrows or tunnels, each with a small exit, for the most part open but sometimes partly filled with web. have generally been attributed to the orange tortrix (Tur- ///./ ci(rana'). Xo other tortricid larva appears to have been recorded as injuring citrus in this state, although several species have been reported as minor pests of the orange in Florida. REARING WORK AT ALHAMBRA. In 1915, some oranges and lemons attacked by lepidopterous larva? were collected at Alhambra and placed in rearing cages. The moths which emerged differed greatly from the orange tortrix (T. citrana) and proved to be identical with specimens reared in July, 1913, from larvae collected in citrus nursery stock at Whittier. This same species did considerable damage during the spring of 1915 to the young growth of citrus nursery stock on the laboratory grounds at Pasadena by rolling up or binding together and destroying the tender bud leaves. Speci- men.-, of these moths submitted at that time to Dr. H. G. Dyar of the I'. S. National Museum, were identified as Platynota sp., and more recently August Busck determined material from the same lot as /'////- in/fa tinctana Walker. OUTBREAK OF ORANGE WORMS IN 1916. A severe outbreak of orange worms occurred during the autumn of 1916 in the Alhambra-Pasadena district, causing a heavy loss of fruit. This outbreak was reported by Quayle 1 who attributed the injury solely to the orange tortrix. The writer, however, made a care- ful study of the situation at that time and collected many larva- and infested fruit in orchards suffering most severely. The moths which emerged proved to be partly Tortrix citrana and partly Plat]) not a tine- tana. More recently (1919) reports of severe tortrix injury in Orange County led to an investigation of fruit conditions in packing houses and orchards with the result of proving the damage to be due to both species of orange worms. The orange tortrix, however, predominated at the time of the inspection in August. SIMILARITY TO PLATYNOTA. This pest appears to be identical with specimens of Platynota which were highly destructive to carnations, asters and chrysanthemums at Hollywood in 1913 by destroying the buds, webbing together the leaves or eating into the stalk. The moths have frequently been observed 'California Citrograph, April, 1918, p. 133. 239916 342 THE MONTHLY BULLETIN. about lights both at Pasadena and Alhambra at times when a careful search of the nearest citrus trees failed to show evidence of infestation. In a letter enumerating the known food-plants of this insect August Busck states that "the species of Platynota are all general feeders and that orange is only one of the food-plants of Platynota, tinctana Walker. In fact I have it in the collection from various greenhouse plants and from cotton and carnations." DESCRIPTIONS. The adult The adult is a rather small moth, with pointed head and somewhat heavy forewings which, when folded, form a rooflike ridge over the body. The females are a variable grayish-brown with a faint indication of an oblique darker colored band on each wing. They aver- age slightly less than half-an-inch long with folded wings. The males are fully one-third smaller than the females, somewhat darker and the surface of the forewings is roughened with elevated tufts and ridges of coarse scales. This tufted and ridged condition of the male fore- wings, their darker color and conspicuously smaller size, readily dis- tinguishes the adult of the orange webworm from the cinnamon-colored smooth-scaled, V-banded orange tortrix. The egg The eggs are deposited upon the surface of leaves in patches of transparent yellowish-green color, each egg overlapping another after the manner characteristic of this group of insects. The larva The larvae are dark colored with a conspicuously black head. This coloration readily separates them from the greenish-white larva? of orange tortrix. HABITS OF THE LARVA. When present on fruit-laden orange trees the larvas are usually found webbed within old dried leaves or fallen flower petals close to the fruit, or even webbed against the fruit itself. Not infrequently they lurk in the protection of touching fruit, especially if in large clusters. The fruit is damaged through puncturing of the rind. The orange web- worm does not appear to confine itself within the burrows in the fruit so closely as does the orange tortrix, nor does its burrow usually pene- trate so deeply toward the rag. PARASITES OF ORANGE WEBWORM. The worm and pupa are highly parasitized even as is the orange tortrix. At least three distinct species of hymenoptera have been reared from the Iarva3 and pupa3, including two internal species and one ectoparasite. These parasites appear able to control the pest except on occasional years. An example of the rapidity with which natural control may occur is well shown by the history of an infested orchard in Orange County. Worms had been abundant in the spring and were numerous in August. Specimens collected during this latter month were heavily parasitized. An examination the following May failed to reveal a single worm and evidence of injury to the new crop of fruit was difficult to find. THE MONTHLY BULLETIN. 343 DISTRIBUTION. Mr. Busck gives the distribution as the west coast of the United States extending down into Mexico and Central America. The apparent wide distribution of this newly recorded orange pest and its diversity of hosts portends a recurrence of its attacks to oranges from time to time even as has been the history of the orange tortrix. The writer's studies, however, lead him to believe that the pest will prove less injurious than the tortrix. SEED PRODUCTION OF THE CANADA THISTLE IN SOUTHERN CALIFORNIA. By ETHELBERT JOHNSON/ Sacramento, California. The Canada thistle, Cirsium arvense, is a weed pest with an exceed- ingly bad reputation which is not yet widely distributed over California. Patches of it are found, however, in Orange and San Bernardino coun- FIG. 95. Heads of Canada thistle, in the order of their stages of development ; Top row, the female; bottom row, the male. (N. Z. Journ. Agric.) ties, and at least one infestation has been reported from Los Angeles County. It is also more or less abundant in Humboldt and other northern counties. In the south, the Canada thistle produces seed rarely or not at all. Unlike other thistles, the Canada thistle produces two types of flowers, male and female, which are nearly always borne on separate plants. The male heads are nearly round, short and stumpy, and more or less 'Technical Assistant, California Department of Agriculture, Sacramento, Cal. 344 THE MONTHLY BULLETIN. flattened near the top. The female heads are somewhat elongated, and narrowed in at the top. For seed to be formed it is necessary for the pollen to be carried by insects from the male to the female plants. Even then seed is frequently not formed, since hot weather destroys either the pollen or the stigmatie surface, and fertilization fails to take place. Most of the patches in southern California have apparently devel- oped from a single seed, hence are usually of one sex only, and the development of seed is impossible. In company with Earl L. Morris and G. W. Wardwell, I examined a large number of female heads in various localities of the Santa Ana delta section this season (1920) but was unable to find a single via hit- seed. That seeds are occasionally formed in certain years is not improbable, although its spread in that section can be explained by its introduction as an impurity in imported beet seed and by the washing down of pieces of the rootstock from lands upstream during the heavy floods which occasionally occur. In spite of the handicap of not producing seed, the Canada thistle is an exceedingly unwelcome intruder. Its rootstocks are not infre- quently twenty feet long, producing plants at frequent intervals, and being exceptionally persistent in the face of control measures. In fact, the only means known to eradicate it is to prevent it from forming green leaves over a period of two years. BEAN WEEVILS IN CALIFORNIA.' i:\ ANDREW O. LARSON^ Alhambra, Caliform';i. LOSSES FROM BEAN WEEVILS. According to statements from officials of the California Bean Growers' Association, and others, who are prominent in the bean industry in California, losses caused by bean weevils 3 have been gradually increasing year by year until 1918 when an exceptionally haevy loss was sustained. Apparently a number of factors combined to make losses greater that year than ever before. Some of these factors are: (1) The greater acreage and correspondingly greater yield; (2) early planting of much of the crop; (3) spread of weevils, through seed or otherwise, to pre- viously uninfested areas; (4) unusually hot weather in some sections early in the summer; (5) unseasonable rains early in September; (6) shortage of labor. The U. S. Bureau of Crop Estimates gives the acreage of 1917 as 558,000 and the California Bean Growers' Journal, Vol. 1, No. 2, page 24, estimates the yield in 1917 as 3,616,000 centals (100-pound sacks) ; while in 1918 it was 4,405,000 centals, exclusive of limas, which are estimated at 1,545,000 centals. According to H. W. Nimms of the California Bean Growers' Asso- ciation and J. E. Clifford of the Sacramento Public Bean Cleaner, and others, the early beans are looked upon with disfavor and are put onto 'Published with the approval of the Secretary, U. S. Dept. of Agriculture. 2 Scientiflc Assistant, Bureau of Entomology, U. S. Dept. of Agriculture, Alhambra, 'Bruchus obtectus Say and B. quadrimaculatus Fab. THE MONTHLY BULLETIN. 345 the market as soon as possible because the degree of infestation is likely to be high. "They are good beans to be rid of." A quotation from the Pacific Rural Press of April 12, 1919, while of questionable value in itself, gives the opinion quite generally held by many of the leading bean growers : AVOID BEAN WEEVILS. "To avoid weevils in Lady Washington beans, David Klotc of Sacra- mento County believes July planting works. In 1917 he planted a few in his garden late in May and got about 100 pounds, all 'buggy.' In 1918 he planted about July 7 and got no bugs, though a neighbor with three acres planted about June 1, 1918, harvested 21 sacks, ' alive with bugs.' Mr. Kioto's beans matured in fine shape from July planting, as this variety requires only about 90 days." "While some bean-growing sections such as Salinas and Lornpoc are free from weevil injury, other sections, notably points in the San Fernando Valley, reported weevil injury in 1918 for the first time. Various parts of California reported unusually hot weather in July and August, causing bean blossoms to fall and early beans to ripen prematurely. The north and central parts of the state received an unprecedented amount of rainfall beginning about September 11 and continuing until early in October. It did a great amount of damage to prunes, raisins and beans. The rainfall, together with the shortage of labor, made it necessary for the beans to remain in the fields longer than usual before thrashing. The labor shortage was also felt in the warehouses, where many of the beans were stored before they were properly dried. Many of the warehouse men claim that beans which have been rained on "always get buggy." Whether the foregoing or other reasons caused the greater activity of the weevils, the fact is that they caused an enormous loss estimated at from 2 to 33 per cent of the crop, according to the variety of beans. While exact figures are not available, estimates from various well- informed men from the bean centers Sacramento, San Francisco, Stockton. Modesto, Los Angeles and San Diego all agree that the above estimate is conservative.. David F. Lane, general manager of the Turlock Merchants' and Growers' Association, Inc., said: "My idea is that one-third of the crop of 1918 was infested with weevil. I do not think this is exaggerating. I base this percentage on the amount of offerings or samples that we take during the day. Out of eight lots we have had to turn down four, and out of twelve lots, ordered to be inspected by a certain bank, we had to turn down four. In taking a general average of all beans offered us during the week I do not think that Ave have been able to accept more than 66 2/3 per cent." While this undoubtedly is true in a very large bean-growing section adjacent to Turlock. Modesto and Merced, it seems too high for the entire state. J. Waterman of the Waterman Selling Agency in Los Angeles and Oxnard, said: "Ten per cent injury from bean weevils to all varieties of beans in this state is very conservative. While it is a little too high for limas, it is far too low for some other varieties, notably pinks, black- eyes and whites." Accepting Mr. Waterman's estimate of damage and 346 THE MONTHLY BULLETIN. 5,150,000 as the number of centals of beans produced and 8 cents per pound as the value of the beans (which in the fall of 1918 was low until the importation of Oriental beans broke the market) we have a loss of 515,000 sacks of beans, worth $8 per sack, or $4,120,000. If this estimate is even cut in half, the loss is still enormous. IDENTITY OF WEEVILS CAUSING DAMAGE TO BEANS. As far as the writer has been able to learn, this injury is all caused by two species, the four-spotted weevil (Bruchus quadrimaculatus Fab.) and the common bean weevil (Bruchus obtectus Say.). Before this investigation began, it was supposed that the common bean weevil was causing all the damage, as B. quadrimaculatus had not been reported in the state. However, the writer finds that W. B. Parker collected speci- mens of this species in El Centre in 1913. It is now quite widely distributed, specimens having been taken by the writer from Sacra- mento, Lodi, Stockton, Ripon, Los Angeles, "Wilmington, Huntingtoii Beach, Santa Ana, Puente and Corona. NOTES ON BRUCHUS QUADRIMACULATUS. Bruchus quadrimaculatus confines its operations to black-eyed cow- peas, as far as the writer has observed, but others, notably Dr. E. A. Back (Farmers' Bulletin 983) reports it attacking other varieties of peas and beans. This led the writer to try to rear it on Mexican reds, pinks and Lady Washingtons. After daily observations as to the variety of bean on which it prefers to oviposit, the writer concluded that its preference was in the following order: first, Mexican reds; second, pinks; third, blackeyes; and fourth, Lady Washingtons. Because of this decided preference for the Mexican reds and also because the eggs can be seen most easily on that variety, it was used for making daily records of the number of eggs deposited by each of a series of females during their lives. As a result, eggs were laid by each female on all varieties but principally on Mexican reds. All the eggs were put together in one container for each day. Towards the latter part of the series only Mexican reds were used. Between July 7 and 25, 5718 eggs were deposited; of these 2661 were on Mexican reds having no other variety among them. Of the other 3057 eggs, the majority were on Mexican reds and 358 weevils emerged from the black-eyed cowpeas. Approximately two-thirds of the eggs deposited on black-eyed cowpeas produced adult weevils, while not a weevil emerged from the other varieties of beans. The young larvae in some instances had bored into the cotyledons of beans other than blackeyes far enough to show tiny cavities after the testa had been removed, but usually the larva? died while trying to bore their way through the testa. The length of time required for the life cycle varies not only with temperature and moisture but also with the offspring of single pairs where the eggs were deposited within a few seconds or minutes of each other and were kept in the same small container until emergence. From 90 eggs deposited on 77 black-eyed cowpeas June 7, 52 weevils emerged, the first one appearing July 10 and the last one on July 29 ; while from 57 eggs deposited the following day (June 8) on 54 cowpeas 28 weevils THE MONTHLY BULLETIN. 347 emerged, the first one on July 8 and the last on July 25. Of a lot of 196 eggs deposited August 15 a variation of 16 days was noted from the time the first weevil emerged until the last one appeared. Thus the weevils required from 33 to 49 days to complete their life cycle. During the period June 8 to December 18, four generations have developed, as follows : (1) June 8 to July 8 30 days (2) July 8 to August 1033 days. (3) August 10 to September 17 38 days. (4.) September 17 to December 18 92 days (first emergence only). There appears to be little if any difference in the time required for the development of males and females but when confined on dry beans or cowpeas the life of the adult females is from 2 to 5 days longer than that of the males. During the summer, the females lived from 9 to 20 days, while the males lived from 7 to 19 days, with the majority living only 14 days. Mating usually takes place a few hours after emergence, and egg laying begins the next day, but sometimes eggs were deposited before the weevils were 24 hours old while in other cases several days elapsed before oviposition began. The number of eggs laid varies daily with the same individual and with different individuals, the greatest number usually being deposited when the weevil is about 3 days old. Thirty- nine eggs in one day and 117 for one individual are the highest numbers recorded by the writer. In summer, 85 is about the average for one female. The following is a typical example: (the female emerged September 20 and died October 6). Sept. 21 :22 :23 :24 :25 :26 :27 :28 :20 :30 : Oct. 1 :2 :3 :4 :5 :6 Eggs 15:17: 4:13: 6:15: 7: 0: 4: 0: Eggs 2:0:0:1 :0:0 Total 84. So far as the writer has observed in the field, eggs were deposited only on the pods of black-eyed cowpeas, usually only a few eggs being found on a pod ; but as many as 63 have been found by the writer on one pod. Apparently the weevil prefers to oviposit on pods where the cowpeas are just beginning to harden, the writer having never observed new-laid eggs on ripe pods where green ones could be found. The eggs are laid singly and are firmly cemented to the pod in the field or the bean in storage. As the young larva bores its way through the under surface of the egg it fills the eggshell with borings, giving the shell a straw- white appearance. NOTES ON BRUCHUS OBTECTUS. The habits of Bruchus obtectus are quite different from those of B. quadrimaculatus, although the larval stages are very similar. In the field, B. obtectus gnaws a hole in the green pod, showing a dislike for only limas and teparies among the many varieties observed by the writer. However, it successfully attacks both of the above varieties. The holes are gnawed into the sides of the pods or into the sutures, pref- erably the dorsal suture. After a hole has been made eggs are deposited therein. Following the deposition of each egg the weevil turns around and uses its mouth-parts to force the egg further into the pod. The 348 THE MONTHLY BULLETIN. writer has observed one female thus deposit 14 eggs in 5 minutes. He has counted as many as 67 eggs which had been thus inserted into one hole adjacent to the dorsal suture. While this weevil inserts its eggs in young, tender pods it prefers to find pods that are ripe, as these usually crack open at least for a very short distance along the dorsal suture. These tiny openings in the suture are found and the eggs are deposited in them in great numbers. The early beans are far enough advanced to receive eggs before the later pods are sufficiently developed. When the early pods ripen and begin to crack open the weevil appar- ently confines its attack to them, leaving the later beans free. In stored beans, B. obtectus eggs are deposited loose among the beans so that a little agitation causes them to fall to the bottom of the con- tainer. A casual observer, therefore, does not see the eggs at all. It appears that B. obtectus shows more uniformity of oviposition and emergence than does B. quadriniaculatus. Equal numbers of eggs of each species when deposited the same day and kept under like condi- tions show that B. quadrimaculatus will begin to emerge from two to five days before any of the others appear but it also continues to emerge several days after B. obtectus is through emerging. B. obtectus seldom oviposits until it is two or three days old; then it deposits a fairly uniform number of eggs daily ; the daily and total number of eggs being as a rule smaller than is the case with B. quadrimaculatus. The period during which the former oviposits is the greater. Typical Examples of Egg- Laying of B, obtectus. Both Emerged June 30. July 1: 2: 3: 4: 5: 6: 7: 8: 9:10:11:12:13:14:15:16:17 :Total :Died Eggs 0:15:15: 5: 5: 7: 5: 7: 4: 7: 2: 5: 0: 0: 0: 0: : 77 : 7/22 Eggs 0:10:12: 0: 0:11: 2:2:1:2:5:5:0:2:10:3:7 :72 : 7/24 The highest number the writer has observed from one female in one day is 26 and 85 is the highest total recorded by him for the life of an individual. Probably greater numbers are deposited in the field, as the writer has found 67 eggs inside a pod adjacent to one puncture. He has recorded the emergence of 35 weevils from three pink beans. the contents of one pod having only one puncture when collected. He also recorded the emergence of 37 weevils from four Lady Washington beans, the contents of one pod. From the very few days required for the emerging period, it would appear that the eggs in each pod had been deposited the same day if not by the same female. MECHANICAL DEVICES IN CONTROL OF BEAN WEEVILS. Bean dealers frequently suggest that a mechanical agitator could be made which would be capable of eliminating the weevil in stored beans. This led the writer to try shaking vigorously each day a vial containing pink beans with a few B. obtectus and their eggs. On June 26, ten weevils were put on 58 beans in a glass container; they were shaken vigorously each day. No weevils were removed until the last one was dead and the eggs were left in the vial. August 13 emergence began and 116 emerged between that date and August 21. On examining the beans after August 21 they were found to contain 36 dead larva?, i pupa3 and 14 adults, all dead. Of these, one adult and 31 larvae had evidently starved in one bean. There were 28 beans containing no THE MONTHLY BULLETIN. 349 weevils. A check of 48 beans and ten weevils, receiving the same treat- ment except for shaking, showed emergence of 266 between August 7 and 19. Later examination showed 4 larvae, 5 pupae, and 14 adults dead within the beans. Only 12 beans were free. A revolving cylinder with finely perforated walls would probably be effective on a small scale. It could be turned a few minutes every fourth day in warm weather and would throw out the eggs which had been deposited since the last agitation. This, however, would be of no use in controlling B. quadrimaculatus because the eggs are cemented too firmly to the bean. The expense of operating would prohibit its use commercially as a control for B. obtectus. FUMIGATION IN CONTROL OF BEAN WEEVILS. The results of numerous fumigation tests with carbon disulphide show it to be an effective means of control in the warehouse. The fol- lowing data shows the efficiency of fumigation when done properly. The sample, 200 beans, was taken from a lot of badly-infested cranberry beans which had been fumigated 48 hours with six pounds of carbon disulphide to 900 cubic feet. Results of Fumigating Infested Beans With Carbon Disulphide. Number of beans Number* weevils in each Per cent of sample Adults Pupae Larvse P ST t 41 o 205 1 19.5 40 2 20.0 24 3 120 91 4 100 14 5 7.0 9 4 5 7 7 3 5 1 A. 5 2 t) 10 "T" 2 10 1.0 1 12 5 " 200 . 100.0 1 108 393 100 Later trials show that the eggs also are killed by this treatment, the writer finds. NATURAL ENEMIES. Undetermined chalcids have been found working on B. quadrimacu- latus, and a predaceous mite, determined by Dr. Ewing as probably Pediculoides ventricosus Newport, has been found by the writer attack- ing both species. While the mite is a very effective check in the laboratory, it causes so much human discomfort that its use is not to be recommended. 350 THE MONTHLY BULLETIN. QUARANTINE; fah)i SERVICE REPORT FOR THE MONTH OF JUNE, 1920. By FREDERICK MASKEW. SAN FRANCISCO STATION. Steamship and baggage inspection: Ships inspected 88 Passengers arriving from fruit-fly ports 5,901 Horticultural imports: Parcels Passed as free from pests 76,673 Fumigated 1,593 Refused admittance 38 Contraband destroyed 130 Total parcels horticultural imports for the month 78.434 PESTS INTERCEPTED. From Central America: Pseudococcus sp. and Aspidiotus cycmophylli on bananas. From China: Formicid (undetermined) in water chestnuts. Lepidopterous larva in dry herbs. Larva of borers (undetermined) in twigs. From Hawaii: Diaspis bromeliae and Pseudococcus bromeliae on pineapples. Larva of Trypetid (undetermined) in tomatoes. Coccus elongatus and Aphis sp. on betel leaves. Hemichionaspis minor on red peppers. Saissetia nigra and Pseudaonidia duplex on hibiscus cuttings. From Japan: Fungus (undetermined) on Japanese pears. Lepidopterous larva (undetermined) in dried chestnuts and dried fruit. From Mexico: Calandra sp. and Silyanus surinamensis In squash seed. Lepidosaphes gloverii and Chrysomphalus aurantii on limes. From New Zealand: Larva of Diptera (undetermined) in decayed potatoes. From Oregon: Actinomyces scabies, Rhieoctonia and F'usarium on potatoes. Epochra canadensis In gooseberries. From Pennsylvania: Pseudococcus sp. on Gardenia. From San Salvador: Lepidosaphes gloverii and Lepidosaphes beckii on limes. From Washington: Actinomyces scabies, Rhizoctonia and Fusarium on potatoes. LOS ANGELES STATION. - Steamship and baggage inspection: Ships inspected 56 Fish boats inspected 7 Passengers arriving from fruit-fly ports 11 THE MONTHLY BULLETIN. 351 Horticultural imports: Parcels Passed as free from pests __ 65,891 Fumigated 12 Refused admittance 24 Contraband destroyed 21 Total parcels horticultural imports for the month 65,948 PESTS INTERCEPTED. From Alabama: Melanose and Lepidosaphes beckii on grapefruit. From Central America: Pseudococcus sp., Aspidiotus ctidoniae and Aspidiotus cyanophylli on bananas. From Cuba: Diaspis bromeJiae on pineapples. From Illinois: Lecanium corni on black currant bushes. From Mexico: Unidentified weevils in tamarinds. Anastrepha ludens in mangoes. Chloridea obsoleta in tomatoes. From New York: Green aphis and Tetranychus sp. on chrysanthemum plants. Melanose, unidentified fungus and Lepidosaphes beckii on Cuban grapefruit. Melanose and Lepidosaphes beckii on Florida grapefruit. From Ohio: Green aphis on chrysanthemum plants. From Oregon: Rhizoctonia on potatoes. From Philippine Islands: Larva on weevil in sweet potatoes. From Texas: Tetranychus mytttaspidis, Aleyrodes sp. and Ceroplastes floridensis on Cape jessamine buds. SAN DIEGO STATION. Steamship and baggage inspection: Ships inspected 22 Fish boats inspected Passengers arriving from fruit-fly ports 40 Horticultural imports: Parcel* Passed as free from pests 6,436 Fumigated Refused admittance Contraband destroyed Total parcels horticultural Imports for the month -- 6.451 PESTS INTERCEPTED. From Central America: Aspidiotus cyanophylli, Aspidiottts sp. and Pseudococcus sp. on bananas. From Mexico: Diatraea saccharalis in sugar-cane. From North Dakota: Rhizoctonia on potatoes. From Utah: Rhizoctonia on potatoes. EUREKA STATION. Steamship and baggage inspection: Ships inspected Passengers arriving from fruit-lly i Horticultural imports: Passed as free from i i i 5092 8-20 TM UNIVERSITY OF CALIFORNIA AT LOS ANGELES *"'' T~> A nv UNIVERSITY of AT LOS ANGELES LIBRARY MIIVJ-JO^ CAllFOfl^ ^OF-CAIIFO^ S c^ > JITVDJO^ %OJIW3-JO ; CALIFOff^ ^OF-CAIIFO^ ^