al j an aK Mie Ft are 1 —"\" { > 4 \ ia er . =a ree b y, ly NH \ . S ‘ rien, * ‘ > i > ’ Be A x 4 i \ fl if A oF ies wt " eM » NA { ay ' ‘i : i » Gay ry ; aie, ; ee e a Sait er hs ved ’ t WA) ve, j ‘ ’ i = 4 i Fa | i= Sa Bi Noit i es, ea U.S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—-BULLETIN No. 123. L. O. HOWARD, Entomologist and Chief of Bureau. A PRELIMINARY REPORT ON THE SUGAR-BEET WIREWORM. — BY JOHN E. GRAF, Entomological Assistant, ~ Truck Crop and Stored Product Insect Investigations. Issurp FEBRUARY 28, 1914. o xt y cree NY . — . A a WASHINGTON: GOVERNMENT PRINTING OFFICE. 1914, i ‘ ; Monograph apd ca dele coe he ew soe te U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 123 L. O. HOWARD, Entomologist and Chief of Bureau. A PRELIMINARY REPORT ON THE SUGAR-BEET WIREWORM. BY JOHN E. GRAF, Entomological Assistant, Truck Crop and Stored Product Insect Investigations. Issuep FreBruary 28, 1914. WASHINGTON: GOVERNMENT PRINTING OFFICE, 1914, BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Martarr, Entomologist and Acting Chief in Absence of Chief. R. 8. Currron, Executive Assistant. W. F. Taster, Chief Clerk. H. Cuirrennen, in charge of truck crop and stored product insect investigations. . D. Horxuys, in charge of forest insect investigations. . D. Hunter, in charge of southern field crop insect investigations. .M. WesstTER, in charge of cereal and forage insect investigations. . L. QUAINTANCE, in charge of deciduous fruit insect investigations. E. F. Puruirs, in charge of bee culture. yee Buncess, in charge of gipsy moth and brown-tail moth investigations. Roiia P. Currie, in charge of editorial work. MABEL Co.corp, in charge of library. Truck CRoPp AND STORED PRopuct INSECT INVESTIGATIONS. i. H. CurrrENnDEN, in charge. ©. H. Porenor, Wm. B. Parker, H. M. Russert, H. O. Marsu, M. M. Hien, Frep A. Jounston, Joun E. Grar, C. F. Stanz, D. E. Fins, A. B. Duckert, F. B. Mr11KkEn, entomological assistants. I. J. Conpir, R. 8. Vare, collaborators in California. W.N. Orp, collaborator in Oregon. Tuomas H. Jonzs, collaborator in Porto Rico. Marion T. VAN Horn, Pautine M. Jounson, Anira M. BALiinGER, CECILIA Sisco, preparators. D, CF D. MAR 27 1914 LETTER OF TRANSMITTAL. U.S. DEPARTMENT OF AGRICULTURE, Bureau OF ENTOMOLOGY, Washington, D. C., February 24, 1913. Sr: I have the honor to transmit herewith the manuscript of a paper entitled “The Sugar-Beet Wireworm (Limonius californicus Mannh.),” by John E. Graf, an entomological assistant of this bureau. This very active enemy to the sugar beet in the Pacific region has been the subject of study in the Bureau of Entomology since 1909. The present paper is somewhat preliminary in character, but so many facts have been learned that it is believed advisable to submit them for publication at the present time. While this wireworm has been known in America for many years, no good report of its injuries was available until very recently. The paper sets forth the manner of injury, the history of the species, the insects associated with it in the destruction of the beet roots in different stages of growth, the number of its food plants, its life history and habits, suggestions as to the methods for its control, and other useful data, and is well illustrated. I recommend the publication of this manuscript as Bulletin No. 123 of this bureau and would urge that it be issued at an early date, as there is great demand for information on the part of the sugar- beet growers of the country, all of whom are more or less troubled by the ravages of wireworms. Respectfully, C. L. Maruatt, Entonuoldigit a ind Acting Chief of Burcu: Hon. JAMEs WiIson, Sap Secretary of Agriculture. a a : - } 1 See A i La ris } } bie ates & ‘ . yeas ig tees mia ; weet Prearkicct > ee ane Saka, ape ata net Ret ha AS eae , : Ab 416 Te Tat Peon rshL sae Laden? cieiehh nob ye : ‘ ea aides pre Eee ae he Rs KF le o ae ae te ome cog taaolees Gt: Bae a sh) 3g Pe Vee aeEae “ait Peay rg imme aay inala.| pee hha date: hertrai paride boy Hatter 3 2 al r a Pe 5 q hee ia ‘3 ee a oh ‘ wie adilelaes ore ‘econ ae tae sa phasing bi. santa use Sita baang pert Ore PREP ACK: The present bulletin is intended as a preliminary report of the investigations which have been carried on with the sugar-beet wire- worm (Limonius californicus Mannh.) since 1909. The life-history work has not been completed; in fact it was not until the spring of 1912 that it could be started on a scale which gave any promise of ultimate success. As tests of many of the control measures were finished during the latter part of 1912, and as it will be several years before a complete study can be finished, it has been decided to publish a report at this time giving all the observations and experi- ments which have been carried on thus far. During the coming years, in addition to the completion of the life-history studies, work will be carried on with other control measures. The relation of the birds of the sugar-beet fields to the wireworms will also be investigated, as will the bacterial and fungous diseases which have been observed to affect this species. The author wishes to acknowledge his indebtedness to Dr. F. H. Chittenden and Mr. H. M. Russell for assistance and suggestions throughout the work. Mr. Russell began the study of Limonius californicus in 1909. The cooperative work of Mr. R. S. Vaile, of the Ventura County horticultural commission, and Prof. H. S. Fawcett, of the University of California, is also deserving of grateful acknowledgment. J. Be G. 5 CONMEEN TS: [ESET ET UD Beh See ae eee cee ge Rte Seka SS Re PERE ES oe oa a tosses due to the:sucar-beet witeworm:........o2.sg-esSesc 2 oe de Bape Insects found with the sugar-beet wireworm........-.-.-...----------+++--+-- Wlasuhcation. synonymy. and common, names... =-245: ~.0 1. 2j35.2 3 eweeees DEER RTOS SA ee a og eA oe a a eR PPE is 8, PUI pea pers sehr ce oa sh arash AIS Sn VR PER NE Baier eet SER Oe aC plAnth eke 22 tek cab eee aot oe oes EE a eee SELEY Hae fe ila basthony cma) Ma Oats =o tote cet we pert ec fay eee oS aes od NE eee 1 VOY SX 22 e ey e, SeIS RON eEES OUELD T E A 0 nam SEE Pm tg tes Ree aaa! amend placeiol deposition) + sos. its) 8s od seen sac Sete Number and-hatchine of eves 2 20. eed Sok Balen ses See Menotin Gibeoe Star ec ce er ee eRe eels t penta Risen Bek etal ANSE Vea SNe fe Yat errno PONE re orey Se Re eras SI OR ee oats eae Pa emergence. inom, thre epi in oes ok Soe arte. nd o hela eee Whe mien ty wnabenen Maeve Meche oop eee ig by oP a nets VGATIne Capea mined a. sete hake cle eee ies pers! te lg Faas ee ie hae 2 Se iHabitstol the younmawireworms: seit y5! ohn GAs se ds thette tk =: Approximaterlength of larval. stage.“¢ 5: coe ssiod: Goleeciiwcles Hied-- Alb ITS Olu e Ol derawakeWwORMss nes ee aeee ee setae See oe eee Rocationsol food, byatheawireworms:...2.3:2/-ce arise ees eae el Te. Activaty of the. ware WwOLMss. 222 hei Senisce ot iiea? sejadsebs woh. Wirewormemjury to beets: 24 2ccerynns tis o2. eesice Set gle Se Time the wireworms can live without food................-.-------- Relation between injury in the beet fields and the size and abundance Ole wine wOnIs ae Ss nw ohn ore ee iS in ie Sener os poe Molting of the wireworms...- . eR piece Sa Pe anad BRS ct DTS Le eer epee Tenner ee Petar Sse Seo SL Bee eal Sek Se eR ed) DED SR EAT avy ALOU bey pee Peak eee Seen ree eg ORR Eee Pa Se tee Re eT ame Mie younalycelll ss. Ae ees cy hoes Breede re ae ae eee, inte Soil conditions aikcewne pupationas 2.) 225.00. Sood S222 eat ead Watality. of the wpa ses to teen Senn Re? See Changesanicolonol che pupacsassia yoo see te Sareea Re). . eee es > =e eneth of thepupal. stages 234-25 as snot Ra ee eee ERR Tale Ne 0 (0 Kas ae eet etree ene Benes Pe eee ee eS ik, ee ere nerrenceol the adult..: <.c% aev aay sean ete Seas Yenc Beriodioiemerg ences 5.42 ace ae ot beg Ae Re ds ees = Aetions directly ather emereence 3: 5-06 cet eee 2-2 Shak Soh 2S - Appearance at bectles\in. the springs... poke. sea vss ee eS Beginning ofthe period of activity... 7-22.25. --2acs.-2's: =24 sos eke Variation in the size of beetles... .-. BE 2 Sl aes Na si ae ea 8 THE SUGAR-BEET WIREWORM. Life history and habits—Continued. The adult—Continued. Page. Variation in’ the coloroftseetles= = .45- 5-542 5. 55262. -252 4a eee 34 Feeding of the adults, and food plants.--.22--2-5:¢ <2 2--2.. 22 See 35 Styles of rearing cares mised ewe. oo Sok oe eee wee eee Fs 36 Duration of life under varying conditions. ...........-.------ Beer 37 Length of time adultsican be'submerged -- . -:-.--+2--- et)--- +2252 - 38 Effect of temperature on thevadulis: =. * 2 222 cee eee 39 Ability of the adults to withstand unfavorable conditions. ........-.--- 40 Method and),time’ofaating.2 2 -tebsse es ee ee 49 Actions of the adults after mating.............------ SEE ey 3 ee 41 Ovi positionat se ee ee eee 46 Natural controls. tsa cs ose et Oe Gee ee ee ee ne 46 Enenues and checks ‘tothe beetless..52...taee eee eee 46 Hnemiesiand checks ‘tothe larvee:. 52-2 2 e224. oe ee eee 48 Fungiatiecting the pups and eggs. 025-2 sssecde ne tesa Se ee ee 49 Remedial measuress:.<2522 4252-2 se sete set Re eee 50 Historical j.25.2 2226 2ee Sets icin ck ck ecte eet ee ee eee 50 Tests of suggested remedies against the sugar-beet wireworm........------ 50 Attempts to destroy the adults with poisoned baits............---.--- 50 Fall plowing for destruction of the pupe......-.-..------2---+--+--+-- 51 Experiments with deterrents against the wireworms...........-.-.---- 52 The use of potassium cyanid against the wireworms...........-.----- 59 Experiments with poisoned bait against the wireworms.......-....--. 60 Experiments with guano fertilizer: . 2... 2.22222 -2e See ee ee 61 Protection of beets-by carly planting: : ..2-. 2) 222 2a eee 61 Clean culture against theadultey.22 02 2s. Se eS eee Eee as 61 Summary -......tateeest notes See h aes chee ee oe ee ee ee ee ene re 64 Bibliography ...\. 2:2 cseegect is 2 sket eee oee ee eee See ee eee 64 Puate I. TE XII. XIV. TELS eA tT LONS: TLATES. Adults of the sugar-beet wireworm (Limonius californicus), showing AYE Vine AVON STORE 7S al an Age BR i cigs or ee es Seen Stages of the sugar-beet wireworm. Fig.a.—Adult. Fig. b.—Newly hatched larvee. Fig. c.—BEggs:..2---2.---2.- 0.02. Sp ei . A sugar-beet wireworm in process of molting...............-...--- . Wireworms and wireworm-like larve..............-------2------6- . Papwolthe sugarbestiwirewormsc 5. yi 2ee) Ju... SO Ske Ee. . Injury by the sugar-beet wireworm to germinating beans.........- . Injury by the sugar-beet wireworm to germinating bean, enlarged - . . Fig. 1.—Sugar-beet wireworms in petri dish, killed by bacteria in cultures of agar. Fig. 2.—Root cage used in rearing young wire- . Work of the sugar-beet wireworm. Young sugar-beets, showing injury by wireworms to taproots; blackened feeding marks visible ONFEMCHOLNOOINS. ste cee at ee eee Me tee Ra Ses te Se SE . Work of the sugar-beet wireworm. Nearly mature beets killed by wireworms; blackened feeding marks noticeable on taproots.-.. . - . Work of the sugar-beet wireworm. Mature beets, showing old scars Fests irons, Ware WORM ADIN s see ss eee oe ee . Ravages of the sugar-beet wireworm. Beet field, showing small cleared space resulting from the work of wireworms...-......-.--- Ravages of the sugar-beet wireworm. Beet field, showing cleared spaces resulting from the work of wireworms..............------ Ravages of the sugar-beet wireworm. Beet field, showing cleared spaces, more extensive than in Plate XIII, resulting from the work COVER all Syy/A0) 001 Eee gre a oo EY Sea rR GES «ine rane ea A . Ravages of the sugar-beet wireworm. Beet field, showing very large cleared space resulting from the work of wireworms........-..---- . Adult of the sugar-beet wireworm issuing from pupal skin.......-.- . Habits of beetles of the sugar-beet wireworm. Fig. 1.—Beetles of the sugar-beet wireworm in secondary hibernation under slice of sugar beet. Fig. 2.—Beetles of the sugar-beet wireworm photo- graphed while feeding on slices of sugar beet....-.....-.-------- . Secondary hibernation of the sugar-beet wireworm. Beet tops used by beetles as quarters for secondary hibernation...........--.---- . Fig. 1.—Field of young beets at age when they begin to be partially safe from severest injury by the sugar-beet wireworm. Fig. 2.— Beet field showing conditions favorable for increase of wireworms. Weed hedges which shelter adults in secondary hibernation... . - - . Conditions favoring the sugar-beet wireworm. Beet field imme- diately after harvest, showing beet tops carelessly scattered over Page. 12 12 12 12 16 16 16 20 24 24 24 24 24 24 24 32 32 36 60 60 10 THE SUGAR-BEET WIREWORM. PuatE XXI. Clean culture against the sugar-beet wireworm. Natural method of clearing off beet tops, by pasturing cattle in the field. which has been inclosed by a temporary fence..........------ XXII. Clean culture against the sugar-beet wireworm. Collecting the beet tops in piles and hauling them from the field as food for XXIII. Conditions favoring the sugar-beet wireworm. Fig. 1.—Beet fields separated by a strip of alfalfa. Fig. 2.—Field of alfalfa adjoining field of sugar beets ...-...-.---.-. Tier omer see Bee TEXT FIGURES. The sugar-beet wireworm (Limonius californicus). Details of larva. 2. Map of California showing counties from which the sugar-beet wire- worm has: been reported ssi fo: Soswkes sis eee Se ee Injury by sugar-beet wireworm to field of sweet corn, Dominguez, Cal. 4. Diagram showing the period eggs of the sugar-beet wireworm were in the soil, with temperature; season of 1912, Compton, Cal......-. 5. Janet ants’-nest plaster-of-Paris cage, used in rearing sugar-beet WANE WOLMIS Ae 2 2 ests Sea cs Seen I Raat eer eae 6. A sugar-beet wireworm devouring one of its own kind; to illustrate cannibalistic habibasoa2 a ace ee see ee Sean Sect ey ote Diagram showing length of life of sugar-beet wireworm without food. - 8. Screen cage used in observing oviposition of adults of the sugar-beet wireworm under field ‘conditions: <_.:2.-2.-,.)-avaeee ous seeeeee 9. Diagram of beet fields, to illustrate the effect of clean culture in reducing injury by the sugar-beet wireworm............-.-...--- Fie. e ° ~J Page. 60 60 60 THE. SUGAR-BEET WIREWORM. (Limonius californicus Mannh.) HISTORICAL. The sugar-beet wireworm (Limonius californicus Mannh.) has been known in the coast lowlands of southern California for many years, having been more or less destructive to sugar beets during the time they have been grown here, and prior to that time was known as an alfalfa and corn pest. In many localities the alfalfa had to be plowed up and replanted every few years, as the ravages of this larva so thinned it out that only a partial crop could be harvested unless replanting was resorted to at intervals. Owing to the fact that the ground in the alfalfa fields is nearly always damp to the surface, the wireworms seldom worked deep, and while they tunnelled through the crown of the plant, it was only a chance injury or a heavy infesta- tion that could make itself felt, so that its destructive powers in the alfalfa fields is proof enough of its abundance. The wireworm has also been noted as a corn pest for years, many growers reporting that on occasions it has been impossible to secure an average crop even with several plantings. Mr. Nelson Ward, of Compton, reports that on pulling up cornstalks he has discovered from 17 to 30 wireworms burrowing through the roots and into the crown of a single plant. LOSSES DUE TO THE SUGAR-BEET WIREWORM. There is great variation in the estimates of losses ascribed to this insect, and very probably the correct estimate would run far above the others. The reason for this is that unless the injury is excep- tional it is likely to go entirely unnoticed. When the wireworms work scatteringly, their injury is apparent only to the observer who is looking especially for it, and at the right time. The writer bases this assertion on observations made during the early spring of 1912. At this time the adults were being collected, and as several hundred acres of beet fields were carefully gone over several times, it was possible, by close observation, to get a good estimate of the progress of the injury and the total damage done. The sugar beets were quite small, having just been thinned, and were consequently at just the right age to receive the greatest injury. The roots were simple, not having swelled, and wherever a beet plant was attacked it was generally killed, as the roots were almost invari- ably severed by the feeding of the wireworms. All the plants which were noted wilting down were examined, and always with the same 11 12 THE SUGAR-BEET WIREWORM. result, viz, the tender taproot was cut and blackened and a search generally revealed the offender, a wireworm, in the soil near by. A great amount of just such work was noted, but it differed from that of 1911 in that it was more scattered. In 1911 the wireworms seemed to be working in groups, and many spots of varying size were completely cleared of beets. In 1912, however, the fields were almost entirely free from this type of work. Places were observed where from three to six beet plants had been killed in one group, but by the time the beets are mature their foliage so covers the ground that all trace of the injury is lost to the casual observer. One incident will illustrate this point. A small beet field of 10 acres located near the laboratory was carefully watched that some idea might be gained of the progress and time of injury. Every day many of the plants were found dead, but seldom were more than three or four plants killed in a place. While this injury was con- siderable it was kept wellscattered. At the time of the last examina- tion the beets, then nearly ripe, so covered the ground with their foliage that even where several adjoining plants had been killed it was difficult to find any signs of the injury. This shows that it is an easy matter to overlook the destructive power of this wireworm. The sugar-beet wireworm may be considered the worst insect enemy of the sugar beet in southern California at the present time. It has this distinction for two reasons: First, it is constant, appearing every year to a greater or less extent; and, second, its injury occurs in such a manner that replanting is generally impracticable, or at least of little value. While beets and alfalfa appear to be the favorite food plants, the sugar-beet wireworm is also very injurious to corn (fig. 3, p. 18) and beans (Pls. VI, VII). It would be a difficult matter to figure the loss due to the wire- worm, either in percentage of the crop, tons, or dollars, but an approximation will show its importance economically. Mr. R. S. Vaile, horticultural commissioner of Ventura County, in his annual report for 1912, places the loss to lima beans alone in his county at $10,000. For 1913 he estimates the loss at $25,000 or more. If the other counties where this wireworm is destructive are taken into consideration it will be seen that probably the lima-bean growers alone lose at least $50,000 a year by this insect. Add to this the loss to sugar beets, which is probably even greater, and it is readily seen that this wireworm presents no small problem in southern California. INSECTS FOUND WITH THE SUGAR-BEET WIREWORM. Collections of wireworms in the beet fields of southern California show at a glance that they are made up of several species. These differ widely in appearance, hence there is little chance of their being mistaken for one another. Two of them, Limonius californicus Mannh. and Drasterius livens Lec., are of the waxy color usually found in PLATE lI. Bul. 123, Bureau of Entomology, U. S, Dept. of Agriculture. 4 eth Ane we ADULTS OF THE SUGAR-BEET WIREWORM (LIMONIUS CALIFORNICUS), SHOWING VARIA- TION IN SIZE. (ORIGINAL.) Bul. 123, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE II. STAGES OF THE SUGAR-BEET WIREWORM. FIG. @.—ADULT. FIG. b.—NEWLY HATCHED LARVA. Fila. c.—EGGs. (ORIGINAL. ) Bul. 123, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE Ill. A SuUGAR-BEET WIREWORM (LIMONIUS CALIFORNICUS) MOLTING; THE CAST-OFF SKIN SHOWING NEAR THE ANAL PLATE. (ORIGINAL.) Bul. 123, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IV. WIREWORMS AND WIREWORM-LIKE LARV4:; THE SuGAR-BEET WIREWORM (LIMONIUS CALIFORNICUS) BEING THE THIRD LARVA FROM THE LEFT, AND THE LARGE ONE AT THE RIGHT BEING A FALSE WIREWORM. ABOVE IS A DIPTEROUS PARASITE. MAGNIFIED. (ORIGINAL.) CLASSIFICATION, SYNONYMY, AND COMMON NAMES. 13 wireworms. The latter is considerably the smaller of the two, and only an occasional individual has come under observation. The other wireworms are white, with a slight yellow tinge. Two of them belong to the genus Cardiophorus, one having been identified by Mr. E. A. Schwarz, of this bureau, as Cardiophorus xneus Horn. The other has not yet been reared, but as several adult specimens of C. crinitus Blanch. have been taken in the fields, it is probable that it belongs to this species. The other wireworm found in the fields is a large, robust, whitish one, considerably larger than Limonius californicus. This has not been reared and remains undetermined. In the spring, when the adults are found in the beet fields, four other elaterids are found with them, though in lesser numbers. The most common one resembles in general characteristics Limonius californicus. It is of about the same size and outline, but differs from L. californicus in the color of its elytra, which are a decided buff instead of a deep brown. Dr. Chittenden has stated that this may prove to be a new variety of californicus, since, while it resembles that species quite closely, it seems to disagree in several small particulars. From the numbers of these which were found with L. californicus it is possible that they may be of economic importance. This species may be called the lesser sugar-beet wireworm to distinguish it from L. californicus. The other elaterids which were found occurred in very small num- bers, so that they may be disregarded from an economic standpoint. These have been determined as Drasterius livens, Cardiophorus sneus, and (. crinitus(?). These three are considerably smaller than L. cali- fornicus and there is therefore little chance of their being mistaken for the latter. Another beetle commonly noted in the fields is a carabid, Platynus sp., slightly larger than L. californicus, robust, black in color, with a slight metallic tinge. Two species of tenebrionids are also commonly found with Limon- dus californicus. Both are short, very robust, and dull black in color. One is Blapstinus sp., the other a species of Coniontis. CLASSIFICATION, SYNONYMY, AND COMMON NAMES. Inmonius californicus (Pl. 1; Pl. II, fig. a) belongs to the common genus Limonius of the family Elaterids. It further belongs to the tribe Elaterini and group Athoi. It was described from America in 1843 by Mannerheim as Cardio- phorus californicus and has since been referred to the genus Limonius. Cardiophorus californicus is its only known synonym. The larvee of this entire family of insects are commonly known as wireworms. The adults, due to their habit of throwing themselves into the air when placed on their backs, have received the names “skipjacks,”’ “click-beetles,” ‘spring-beetles,”’ and ‘“ blacksmiths.” 14 THE SUGAR-BEET WIREWORM. DESCRIPTIONS. Tuer ADULT. Following is the original description by Mannerheim?! in Latin, followed by a translation into English. 136. Cardiophorus californicus: elongatus niger, punctatissimus, tenue pubescens, thorace convexo, subquadrato, elytris dorso depressis, leviter punctato-striatis, sterno profunde punctato, convexo, tarsis articulis omnibus et unguiculis simplicibus. Longit. 54, 44 lin. latit. 12, 13 lin. Habitat in California, D. D. Blaschke et Tschernikh. [Translation.] Cardiophorus californicus: Elongate black, closely punctate, finely pubescent; thorax convex, subquadrate; dorsal surface of elytra de- pressed, feebly striate-punctate; thorax beneath deeply punctate, convex; all joints of the tarsi and claws simple. Length 102-94 mm., width 34-34 mm. Habitat, California (Blaschke and Tschernikh). THE Kaa. The egg of Limonius californicus (Pl. I, fig. c) is for the most part opaque white, though it shows small, irregular, semihyaline areas when placed on a white surface in dim light. The surface appears smooth under the low power of the microscope, but under the high power it appears to be slightly scaly. It reflects light weakly from the lighted side. That the shell is quite tough is proven by the fact that even when the eggs are rolled about in the soil they are seldom distorted. The egg is ellipto-cylindrical in shape. Both ends are broadly rounded and resemble each other. Measurements of 30 eggs gave an average length of 0.69 mm. and an average width of 0.5 mm. The length varied between 0.63 and 0.735 mm. and the width be- tween 0.473 and 0.53 mm. THE LARVA. The nearly mature larva of Zimonius californicus (fig. 1; Pl. II, jig. 6; Pls. III, IV) is subeylindrical in shape and shiny, waxy yellow- ish-brown in color. The segments are very minutely and sparsely punctate. The head and venter are flattened dorsally and darker in color. There is a light dorsal stripe on the posterior end of each seg- ment with the exception of the venter. sik The head is depressed and considerably narrower in front. The mandibles are strong, notched, deep brown in color, changing to black at the tip. 1 Bul, Soc. Imp. Nat. Moscou, vol. 16, p. 238, 1843. DESCRIPTIONS. 15 The first thoracic segment is broad and long, being about equal in length to the venter. The other thoracic segments are short, being about equal in length to the first two abdominal segments. The remaining abdominal segments are a little longer and quite similar. The legs are short and armed with heavy, short brown spines. The abdominal segments are slightly constricted where they join one another. There are from two to four hairs on the lateral side of each segment. The spiracles are brown, conspicuous, and are situated in a poorly defined, light lateral stripe. They are slightly nearer the anterior end of the segment. The venter is depressed dorsally, with raised edges. It is sparsely hairy around the edge. The caudal notch has a small tooth on each side pointing — slightly upward and backward. The margin of the notch varies from deep brown to black. The average length of the mature larva is from 18 to 21 mm., and the width is from 2.5 to 3 mm. Tuer Pupa. When first formed the pupa is opaque white, but after a time the eyes show through as pale, dusky, blue spots. About this time the tho- racic segments become a pale waxy yellow, but ~ other changes take Fic. 1.—The sugar-beet wireworm (Limonius californicus): a, Head; place until shortly be- b,anal segment from above; c, same, lateral view. Highly mag- fore emergence. Se ert ie aaa The pupa (Pl. V.) very much resembles the adult beetle in shape, except that the abdomen is slightly longer in the pupal stage. The head is bent forward slightly, and each anterior angle is armed with a long, heavy spine, which tapers regularly to a point. The mouth parts are conspicuous. The antenne are laid along the margin of the head on the ventral side, and their tips are behind the tibie of the second pair of legs. On the underside of the head and near the prothorax are two short, heavy spines. There are also two short, stout spines on the dorsal side of the head near the posterior angles. The case covering the springing apparatus is plainly visible between the anterior coxe. The leg cases are folded similarly to 16 THE SUGAR-BEET WIREWORM. those of other Elateride. All of the posterior pair, excepting the tarsi, are covered by the wing cases, which are curved around and almost meet on the ventral side, at the distal end of the third abdomi- nal segment. The abdomen is contracted sharply at the seventh segment, so that the eighth segment is only a little more than half as wide as the anterior end of the seventh. The anal segment bears two long, heavy spines on its posterior angles. These spines are slightly divergent, are pitted, and the distal half of each is brown, changing to black at the tip. The pupe vary greatly in size. Measurements taken from sey- eral individuals give an average length of 11.5 mm. and a width of 3.6 mm. DISTRIBUTION. This wireworm is found quite generally throughout the western half of California. It is abundant in the lower sugar-beet lands of southern California. The main districts affected by it are those of Ventura, Orange, and Los Angeles Counties. These three districts comprise probably the choicest sugar-beet land in southern Cali- fornia. The station for the study of this insect was located in Compton, in Los Angeles County, about 10 miles from the coast, and surrounded by about 12,000 acres of sugar beets. Inmonius californicus has been reported from the following — places, all in California: Riverside, San Bernardino, Los Angeles, Lake, Monterey; and El Dorado Counties, by Prof. H. C. Fall; near Owens Lake, collected by Dr. A. Fenyes; Marin County, specimens in the collection of the University of California; Orange, Ventura, and San Diego Counties. (See fig. 2.) Prof. A. L. Melander, entomologist of the Washington Agricultural Experiment Station, Pullman, Wash., reports that in the collection there they have a single specimen which was collected in eastern Washington. It is thus seen that this species is fairly well scattered along the western half of California. It is probably not of economic impor- tance outside this State. FOOD PLANTS. The larve of Limonius californicus have been noted to feed on the following plants: Sugar beet. Alfalfa ( Medicago spp.). Wild beet (Bela sp.). Pigweed (Amaranthus retroflerus). Potato (Solanum tuberosum). Chrysanthemum. Lima bean (all varieties). Nettle (reported by H. M. Russell). Corn (all varieties). Wild aster (reported by H. M. Russell). Johnson grass (Sorghum halepense). Mustard (Brassica niger). Dock (Rumex hymenosepalus), PLATE V. griculture, Bureau of Entomology, U. S. Dept. of A 72 Bul (IWNIDINO) ‘QA9NVINA ‘“LHOIY LV M3IA TVS¥Od ‘371GGI| NI M3IA WWYLNAA +1337] LV MalA TWESlV] ‘ j 4 é "ANHOMAUIM LISG-YVONS SHL 4O vVdNd PLATE VI. Bul. 123, Bureau of Entomology, U. S. Dept. of Agriculture. (CAVNIDINO) ‘3ZIS IVUNLVYN Lnosy ‘SNVAQ DNILVNINYSS OL WHOMSAYIM L3ESG-YVONS AHL Ad AYNEN| (CTIVNISIYO) ‘Q39YUVINA ‘NV3g ONILVNINYSS OL WYHOMAYIAA L33Q-YVONS SHI Ag AYNPN| PLATE VII. Bul. 123, Bureau of Entomology, U. S. Dept. of Agriculture, FOOD PLANTS. 17 It is difficult to note a preference of this wireworm for any par- ticular food plant, as sugar beets, lima beans (Pls. VI, VII), corn (fig. 3), potatoes, and alfalfa all seem to be favored. After these SAN LUIS OBISPO santa Ban 22 eee ee 16-17, 35-36 Jungi affecting pups: ‘and espe!) 25s. ees eee 49-50 habits and life history. \<52 2! Se eee 18-42 hibernation 222 282.22 0s See eee eee 43 “secondary 22 Sass: See SE roars 33, 44-45 INDEX. 67 Page Inmonius californicus, historical... ...-....-- 02.5222 2.28 bE TEE 9 11 Dib 1] 06 27S eee eee ee sci Sic Sen ee 26-27, 29 iNeEectstoune Gere with. 22. oS. CANS Le SS 12-13 dara redescmp ion 225 2.0 5212S. Se Ee 14-15 duraonvet lite without food2ia.s 225... 25215. 27-28 emerzence irom epg: 2.5255 ee eee Se 20 Peapod sete EL eet RR Lees th, Saree 22-26 injury to beets... .- ae Et ees = ene ae 26-27 length of stave, “approximate s. 2. anee00... ee 24 Iie hastory and habits: 22223225598. Pee. 20-30 FOU rat eo Se I RE FO 29-30 Mewhymirateted sais! Deal eee SRI IM 20-21 Pegtineaces Used! ot ost tS LY WSS USO ae 21-22 relation between size and abundance and injury Is becinheldssees sivaws SMe oY Be ce 2688 29 life'cycle; approximate leneth - 2.222.222.2222 ee 42 Mighihy and mAhises seeae te SNe AL Boy UL ae 18-42 loskes'dine to wOrkeene retains. foe. Sete oe Jat 11-12 SCE RUDY a crate Su ln SC hn 40-41 mortality: dune hibermatiomies 2 2 eel 43 NAMES; |COMMMOMS sees ee ese eee eee ese EL REIS Se 13 occurrence of beetlestimitiel dees ss a a eet 45 OVAPOSUtON 2k see eee eee are ete hes ALINE)! Oo) FEE 42 pups, -chanves im colors ee seer cerns on al eed 3l descr ptio ness 2) eee eee ee Ua eh 15-16 lensthiol stage ssa ee ek Rok So ces 31 MG MIS LONYy Sec 2 emer ee eee Se oe 30-31 SULLY GR tes foe ee a eee os eS! 3l Pulpal cell esa a. ee ce ae = aE eel no o's 30 DUP SHON Go ee os core Bas os Ue ete ee cies 22 St 30-31 PETE IAL MICAS ULER oc craic’ atom ee eee ee icy alai ees s «G2 50-64 deterrents against larvee, experiments 52-60 fall plowing for destruction of pupe. - 51 historical 2-0. \.s-coeemer we ee eae Se 50 polsoned halicg = eros nee bee 2 50-51 Sennon a lalnistor yer tetce 1. setys Sy sly Baie Stasis css Se 42-46 soil conditions affecting pupation...-......-.....------- 30-31 SUMMA Vee eters one NOt RASS SNES Le gs soe ee seer 64 NEMO TGV et siesta (eee 8. S22 b: sie ths See epee eter 13 Lophortyx californicus vallicola, enemy of Limonius californicus......--.-.------ 47 Meadowlark, western. (See Sturnella neglecta.) Medicago spp. (See Alfalfa.) Mustard. (See Brassica niger.) Myiarchus cinerascens cinerascens, enemy of Limonius californicus........-.----- 47 INetilesiood plantiotelzmonnisicalijornicisass 6 --- ease = a ee eae eee eee 16 Nicotine, free, solution, against sugar-beet wireworm.................-..4----- 525 O sulphate against sugar-beet wireworm......-............-.---.---.- 52, 57 Nighthawk, western. (See Chordeiles virgvnianus henry.) Oxyechus vociferus, enemy of Limonius californicus.....---- eet fre re fin oka 47 Paris green in poisoned baits against sugar-beet Wireworm........-.------------- 51, 60 .Pigweed. (See Amaranthus retroflexus. ) Platynus sp. in sugar-beet fields with Limonius californicus.............------- 13 Potassium cyanid and flour in poisoned baits against sugar-beet wireworm....-. 60 ‘2 68 THE SUGAR-BEET WIREWORM. Page Potassium cyanid, solid, against sugar-beet wireworm....-......--......-.- 52, 59-60 solution against sugar-beet wireworm................... 52, 59-60 sulphid solution against sugar-beet wireworm....................... 52, 58 Potato, food plant of Limoniis caliormicts-< 224. i>. 26 tae. ee 16, 17 Quail, valley. (See Lophortyx californicus vallicola. ) Rumex hymenosepalus, food plant of Limonius californicus.....-.........--...- 16 Salt solution against sugar-beet wireworm..........-...--------+--------e-e- 52, 58 Shrike, California. (See Lanius ludovicianus gambeli. ) “Skipjacks,’’ colloquial. namesor Blaterida:...-.. -.-.55 --.--~ 212. pee 1B; Soap, whale-oil, against sugar-beet wireworm.............-....----2.-----20- 52, 55 Solanum tuberosum. (See Potato.) Sorghum halepense, food plant of Limonius californicus...-...-...........-.---- 16, 35 Sparrow, native, enemy of Limonius californicus beetles..............-....- ae 47 ‘‘Spring-beetles,’’ colloquial name for Hlateride...........-.....--....-.-..0- is Stormsas checks to Limonius californicus beetles.....-.....---.--------+--+--- 47 Strychnine in poisoned bait against sugar-beet wireworm beetles................ 51, 60 Sturnella neglecta, enemy of Limonius californicus beetles....................--- 47 Sugar-beet wireworm. (See Limonius californicus.) Sulphur, dry, against sugar-beet wireworm . ..2 ....- 2-2 deeses< see vee ses ss aeee 52, 58 Tar water against sugar-beet wireworm .........-.2.-+--2---2--6------20008 52, 55-56 Temperature as affecting adult Limonius californicus......-.-.--...-------+--+- 39 Turpentine against sugar-beet wireworm . 2... - 2 ..-2---2sse2+---+-2022s00e5 52, 53-54 Variaiiomin beetlesof Limoniiuscalifornveus).2-. 2-3: aee eee oie oe ee ee ee 34-35 Wireworm, lesser sugar-beet, undetermined species near L. californicus...-.-.-.- 13 Wireworms Jound in sugar-beet fields...2...)2-tea.b54%,-a0- > te one eee oe 12-13 jee COPIES of this publication may be procured from the SUPERINTEND- ENT OF DOCUMENTS, Government Printing Office, Washington, D. C., at 25 cents per copy nie i baria J hits q 1 eerie Wea i j I } \ i f 4 i IMMA