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DEPARTMENT OF AGRICULTURE, ~ BUREAU OF ENTOMOLOGY—BULLETIN No. 109.-(/' 2, 1% /i"/2 L. O. HOWARD, Entomologist and Chief of Bureau. : PAPERS ON INSECTS AFFECTING VEGETABLES. CONTENTS AND INDEX. f aX 2 IssuED SEPTEMBER 9, 1916. WASHINGTON: GOVERNMENT PRINTING OFFIOE. 1916. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 109. L. O. HOWARD, Entomologist and Chief of Bureau. _ PAPERS ON INSECTS AFFECTING VEGETABLES. I. THE HAWAIIAN BEET WEBWORM. By H. O. MARSH, Agent, Engaged in Sugar-Beet and Truck-Crop Insect Investigations. Il. THE SOUTHERN BEET WEBWORM. By F. H. CHITTENDEN, In Charge of Truck-Crop and Stored Product Insect Investigations. Ul. THE IMPORTED CABBAGE WEBWORM. By F. H. CHITTENDEN, In Charge of Truck-Crop and Stored Product Insect Investigations, and H. O. MARSH, Agent. 3 IV. A LITTLE-KNOWN CUTWORM. By F. H. CHITTENDEN, InCharge of Truck-Crop and Stored Product - Insect Investigations. VY. ARSENITE OF ZINC AND LEAD CHROMATE AS REMEDIES - AGAINST THE COLORADO POTATO BEETLE. 7 By FRED A. JOHNSTON, Entomological Assistant. VI. THE SUGAR-BEET WEBWORM. By H. O. MARSH, Entomological Assistant. VII. THE HORSE-RADISH WEBWORM. é By H. O. MARSH, Entomological Assistant. . => _ ay ‘ ’ meh inl ‘ Wainer igi Dealin én a bel | =e eat il jal it : SM i a aN WASHINGTON: GOVERNMENT PRINTING OFFICE. 1916. BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Maruatt, Entomologist and Assistant Chief of Bureau. E. B. O’Leary, Chief Clerk and Executive Assistant. F. H. CuItTENDEN, in charge of truck crop.and stored product insect investigations. A. D. Hopxins, Forest Entomologist. W. D. Hunter, in charge of southern field crop insect iimestigations. —_—_—__—_____——, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, in charge of deciduous fruit insect investigations. E. F. Pumurrs, in charge of bee culture. A. F. Buresss, in charge of gipsy moth and brown-tail moth investigations. Rous P. Currie, in charge of editorial work. MABEL CoLcorD, in charge of library. Truck Crop AND STorED Propuct INsSEcT INVESTIGATIONS. F. H. CurtTENDEN, Entomologist in charge. C. H. Porpenot, T. H. Jones, M. M. Hieu, F. A. Jounston, anp D. E. Fring, entomologica! assistants. H. O. Marsa, F. B. Mmu1xKen, C. F. STAHL, FrANK R. Coz, A. B. Duckett, B. L. BoyrpENn, R. E. CAMPBELL, W. H. Wuirte, and PAvuLinE M. Jounson, Scientific assistants. NEALE F. Howarp, Specialist. .W. N. DovENER, Expert. II CONTENTS. The Hawaiian beet webworm (Hymenia fascialis Cram.).......- — O. Marsh. . pMPERRCNI rest Ae Unc hs eh ears Ua sate ciclo wr paletealaratela Snlacq 5 2 5 Me eOMMRRMCIR IA HIGH IUIRTLE OOo 8 8. 2 oc ak wae aa aw doe aja GARE aa tapw a een big hie EN at EAMG AIG eh oP ec e o dn ote a Sg aisha Vaal aian wie aoa 8 aE: SE LTE Syl emia tee Rg le le th RU ge gage ye PU eS fag Nl Te ace PEERS Wik ISeCtiCides J... 008 ek ea ine ete as ase canes Mumermiman of the earlier stages/... 2-722 eee ns eee eee OG Dyory: SN lee Sols nie apy <2 aldniae ness tes dale = 2 F. H. Chittenden. . fe-wertoion and Synonymy. ..2-2..-5 9.56... -- ee eee Ua care Gee PeteintviNGn 92) 50)... Slee sbi Sep ca N RM eh Ras Lb cients tN CIRAPAR eee Serre a NAS Ue RE SRI e warn mow alee haa ails ¢ The southern beet webworm (Pachyzancla bipunctalis Fab.)..F. H. Chittenden. . iaiurous occurrences and notes on habits..-.-.2...:25..25.-20-..452-+-: en Ete ta, ua mS! NCE Rok oe tlhe 2's. con citn ~ wwistee @ MCR Pee es Pd OO afaloe dod Aas oe Stoopid ea lye Mae ta th wie (4 Setters iMloptCal Notes 22. 4.308252. o ele Poker S. ME en te er Se er ke EN ogo Oe Ne matte 8 Es DRG Fic Gale Ree I Sealed aii 8 ec ae oie) ieee 4 noel Seppaeee dee ey LA See et Remedies. ...........- Ep geet Oe Gt NAIR Me OR Va le RR cae eh hae eye Rene ees 25 Ok EY ot ee Sate: tn SG Oh Seneiniehn ae op tateeen Wie Aiea meaner Meare eas i tee lee Sieh eas ee cee _ The imported cabbage webworm (Hellula undalis Fab.)...F. H. Chittenden EMERG Sei hye om oS ete RUN ae el ods a es gia ela awe ets Memmreriion spread, ane Tavares. 62 2020 ese eo. a cies dee sos os Description ad HiieshistonamOiedoe asses) Ghee yah Ce oe Meee ct |S TTL) RARER aes Bhagat Sept iat tpi ated ove ean a eek ae Ee COW IPOSIUION Ye. ee hc 2 oe se Se woth ania s bide ae theme oe SEA BL Eline cl 276 UB 2 UU go a Oe SU SELON TALE het SS SS a ae ae ge i ee GI REM a aad e MN fs )oarat Vols am Mic ec Ses wc hw v= cha lee (Pe ae Rep UTION. 2. 2. see ESE eR ORE i LENE Ae Or epee (So Pood plants. .....-.... BE at) Dai SCRE SEL GR xt ge EM Lt ae Je Ta meyer gh On ON bu) os OU a la wd lees Scaled gee ewes ithe imported cabbage webworm in Hawaii.........5...-00s.-.e00c5e ee Pate na ery amt ltetee Sa ek ol Bo eh Matin CNGHIIEN Im EPA Wallis... > -1scns 20. oko otek ee. wecce chee Papenments wittiimseeticies.\.. 2.150) Ahcbidge. Jlel is dee ee Experiment in screening a seed bed.................-.-.0-eeececeee DipmelIOM a Motes ud See ene recat re We mat oe atk as Peemommuese attiond toriconitol sic.) 0.45. Sele od = oa, Qe bec die wa Jada cece UME MPR ce Lou ek es ss wl ee III Page. _ a ey PAPERS ON INSECTS AFFECTING VEGETABLES, Page A little-known cutworm (Porosagrotis vetusta Walk.) ....... F. H. Chittenden. - 47 Enjurious occurrence. >. 322... -_ (ee eee a er 47 Results from applications of arsenate of lead.......... eh ie 49 Description... ...--2---. 2 4. ss a a ee 50 The moth. /2220.0.0 22 ee nc. - ies aac a i ee er 50 The darva. 22.222. 24 +. +. SPP 50 Distribution... 2... . ease ne Re ee ses Re. Bees 8 50 Natural enemies. 222... yon 3-4 5-5 oe Seth mie cle ee oe ee it oe Arsenite of zinc and lead chromate as remedies against the Colorado potato Beetle cose eS i ee ere ee Fred A. Johnston. . 53 Spraying experiments with arsenite of zinc and lead chromate in compari- son with other arsenteals...2. 022. 22-56 So oss pose od es 53 Spraying experiments with arsenite of zinc of different strengths........ 55 A report of progress regarding the sugar-beet webworm (Lozostege sticticalis L.), HT. OY Marsh.. 57 Tntrodvctionxx - 3. 02. cieiwelt(. L Seeeeie 6 A ee ce ee 57 General appearance of the sugar-beet webworm and nature of attack...... 58 Life history and habits........-.-.. ot Fee re te HR Rae ee 59 Character of injury ac... Jo. 2 oe Stat eee hee oe eee Ge pad, Pak 61 Natural enemies. 0... 8 ange Se eee 2 cl 62 ierenecks: 4 Fee ee ee ew ee a eette ass: vote) 2s ",, 2 Experiments with remedies... 022. 22. 2. 2. - oc sees - oe 5s - 2 rr 63 Spraying machinery........... woe Seok Ss oo eb oe oe ee rr 66 Cost of gprayime 0 5 ots co ki ee Le ee cn 1 “69 Conclusion. 20.00 52.020 0.2- 2 nok ee ie one Pe ee 70 The horse-radish webworm (Plutella armoracia Busck)........-- H. O. Marsh... 71 Pniroduction.: = 2005.22. fol le ae i ee oe ee 71 ecumence m Colorada: 2500.2 ce) ies See ee > oad a 71. General appearance and habits... ....--. eer 72 Pic MIBbOry 200s. 8 ae Nn een alee et alte: ¢ eet ante e e 73 Hearing records: 22262222 S Shee 2 ed 73 ee-laying record.) - esi. ee. hes ees. bs. ee ; 75 Natural enguiies .. 4. so. J 2s -ce 8 oes nel <4 oS oe ae ch ts 75 Experiments with insecticides:. -)2- 5.4. «sc s«iec Bel aoe deste 2 76 Recommendations for control.-..-..-..-.0.2.¢-2-sb 44500 = 76 RECIMELOT. «2 Lak oe Goce BC NL ene os oer Sa ation pict bien bi ie Z 76 BACK ote. ck bak bh beso ore eke ete eee ae 77 PLATE . Barrel sprayer suitable for use against the sugar-beet webworm . Barrel sprayer in action against the sugar-beet webworm = Pourrow attachment for beet sprayer. .........-......------- Oh er . Four-row attachment for beet sprayer . Four-row attachment for beet sprayer . Geared traction sprayer suitable for use against the sugar-beet webworm. . Geared traction sprayer in action against the sugar-beet webworm . Filling a traction sprayer for spraying against the sugar-beet webworm. . . Type of Vermorel nozzles suitable for spraying sugar beets against the . The horse-radish webworm: Larva, lateral and dorsal views . The horse-radish webworm: Pupa . The horse-radish webworm: Cocoon ILLUSTRATIONS. PLATE. I. Fig. 1.—Geared traction sprayer, suitable for the treatment of sugar beets against the Hawaiian beet webworm............:2/..-.-2!.- Fig. 2.—Geared traction sprayer in operation in sugar- pee Helo. oe: TEXT FIGURES. . The Hawaiian beet webworm (Hymenia fascialis): Female moth... . -- . The Hawaiian beet webworm: Egg, larva, pupa, details............-- . The southern beet webworm (Pachyzancla bipunctalis): Moth, larva, pee ee ee a ict Mob on Sea tu ya he hnt s tia ic ey Rte a cnt irene ang . The imported cabbage webworm (Hellula undalis): Adult, larva, pupa. . The imported cabbage webworm: Wing venation; head and antenna. . . Exorista pyste, a parasite of the imported cabbage webworm..-.........- Meme conipressed-air sprayer. ..2 220.220...) ok ek ek merosnaroms velusia: Moth, larva.(... 522.22, -..0225---! Be Sey aa . The sugar-beet webworm (Lovxostege sticticalis): Moth..............: hina . The garden webworm (Lozostege similalis): Moth, larva, pupa, details. . . A medium-sized sugar-beet plant defoliated by the sugar-beet web- worm in July en es . Sugar beets defoliated by the sugar-beet webworm in July....:...... . Large sugar-beet plants, showing defoliation and weakened roots due to attack by the sugar-beet webworm in August . Field of young sugar beets destroyed by the sugar-beet webworm in a a a a sugar-beet webworm . The ‘horse-radish webworm (Plutella armoracia): Adult or moth, side view and with wings spread a a -2e es ee es ee we ERRATA. Page 33, line 7, for Agrostis read Agrotis. Page 72, line 14, for scale like read scale-like. Page 76, last sentence, read, In this garden the larvxe have evidently been prudential by a ee haricrous parasite ee causing much damage, and at present no arieficial control measures are necessary. V Page. . s F m % - r - , ‘ al . . i é Shae ' ¢ ps ’ . x ’ . , / Fi es . ri % y 7 * \ ‘ \ \ ' 4 . hs he % pe , R ‘ae ah = Ci Sap mat eta er 2 ear GALE: Hes ee een eb : 4 ce ie v é{ ee . L ty } i, eae ‘ a3 we tel ex 7 Lee, < vi , ve ae ee i ‘ ee a’ Ve Ree sy b AE bys ess ee aaa ; wT “ONCE AN GP wee if Le ete OSI Sie ’ ae i net ee ae we P MAN Ph er oe Pies MDE asta ths “i yey a Sy x / i +f . Y r > + X . + 3 ithe aaa Bh ype aa Y U.S. DEPARTMENT OF AGRICULTURE, a BUREAU OF ENTOMOLOGY—BULLETIN NO. 109, Part I. [0 HOWARD. Entomolonnt snd Chet of Burcan: PAPERS ON INSECTS AFFECTING VEGETABLES. THE HAWAITAN BEET WEBWORM. BY HO] MARSH, Agent, Engaged in Sugar-Beet and Truck-Crop Insect Investigations. [Wits Appenpix By H. G. Dyar anp F. H. CHITTENDEN. ] Issupp NovemBer 6, 1911. cntsenian inst ~ Use ™ ‘70, NOV 10191] - Wy \N. "aA Mana! Mus Urns WASHINGTON: GOVERNMENT PRINTING OFFICE. 1911, BUREAU OF ENTOMOLOGY. L. O. HowarpD, Entomologist and Chief of Bureau. C. L. MARLATT, Entomologist and Acting Chief in Absence of Chief. R. S. CiiFron, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. CHITTENDEN, in charge of truck crop and stored product insect investigations. A. D. HopKINs, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. I’. M. WEBSTER, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, in charge of deciduous fruit insect investigations. EK. F. PHILLIPS, in charge of bee culture. D. M. Rocers, in charge of preventing spread of moths, field work. RoiLua P. CurRIg£, in charge of editorial work. MABEL COoLcorD, in charge of library. TRUCK CROP AND STORED PRODUCT INSECT INVESTIGATIONS. F. H. CHITTENDEN, in charge. H. M. RUSSELL, C. H. POPENOE, WILLIAM B. PARKER, H. O. MARSH, H. Jongs, M. M. HicH, FRED A. JOHNSTON, entomological assistants. I. J. Conpit, collaborator in California. P. T. Cote, collaborator in tidewater Virginia. W. N. Orb, collaborator in Oregon. MARION T. VAN Horn, preparator. LE THOMAS CONTENT S: The Hawaiian beet webworm (Hymenia fascialis Cram.)......-- H. O. Marsh. . 2 PEELE AOI cera coke ees eee ee Re area PPE Ma CECI ME ees Fe Ss ee ale os See cis Pubs es eset es OEE EES POUR GUL L110 FSGS eee ee ee Se ee Momuprmecteimeds. 6.2 8 oo vied. ewes oe ce ea ook ws TT Ns ee eae mepeninicmin with ihsecticides.- 2. .2..22.. 0.2 seeds. ee eed ee lee eee ee Mescription of the earlier stages........-..----+---.--------------H.G. Dyar.. PLEUS TRATIONS. PLATE. PuaTE I. Fig. 1.—Geared traction sprayer, suitable for the treatment of sugar beets against the Hawaiian beet webworm .............. Fig. 2.—Geared traction sprayer in operation in sugar-beet field TEXT FIGURES. Fig. 1. The Hawaiian beet webworm (Hymenia fascialis): Female moth 2. The Hawaiian beet webworm: Egg, larva, pupa, details Page. oA U. S. D. A., B. E. Bul. 109, Part I. T. Cc. & S. P. I. I., November 6, 1911. PAPERS ON INSECTS AFFECTING VEGETABLES. THE HAWAIIAN BEET WEBWORM. | (Hymenia fascialis Cram.) By H. O. Marsu, Agent, engaged in Sugar-Beet and Truck-Crop Insect Investigations. INTRODUCTORY. During the latter half of 1910 the author was engaged in a study of insects affecting truck crops in the Hawaiian Islands. The enemies of beets and of the so-called spinach (Amaranthus sp.) were among the insects which were studied. The species injurious to these two crops had previously received very little study from an economic standpoint, and the necessity of such study was further enhanced by the fact that a land company was experimenting with sugar beets on the island of Lanai! with the intention of growing this crop on a - large scale, if it should offer promise of becoming profitable. In the vicinity of Honolulu, on the island of Oahu, vegetables are erown in commercial gardens, managed by Chinese or Japanese. In a general sense, these growers may be considered “ good farmers” although they have little regard for the necessity of clean culture and seldom make any intelligent effort to combat insect pests or plant diseases. In the rare cases where an effort is made to cope with such troubles, the methods employed are extremely crude. Practically all cultivation is done by hand, except that occasionally the water buffalo is used for plowing the land before the crops are planted. From the Oriental point of view this plowing is considered sufficient if the surface of the ground is scratched to the depth of a few inches. The fertilizing material used is in liquid form. It is prepared by soaking stable manure or other refuse material in water and is appled directly about the plants. Table beets and “spinach” are produced exclusively for the local market. These vegetables are grown in beds, in a peculiar manner, which Mr. E. M. Ehrhorn has aptly designated “the graveyard style.” The beds, which are very often about 10 yards long by 1 1The sixth largest island of the group. 2 INSECTS AFFECTING VEGETABLES. yard wide, are mounded up about 6 to 8 inches above the surrounding surface, the top is leveled, and the seeds are planted on these elevated plats, which have an appearance very suggestive of graves. Although the climate is rather humid the normal rainfall, at Honolulu, is so light that irrigation is necessary to produce a crop. Practically all the gardens have an abundant supply of artesian water, but, owing to the manner in which the beds are elevated, it is impossible to run the water between the rows of plants, and as a result they have to be watered by hand. This is accomplished by dipping up the water in large watering cans and sprinkling it over the beds. It would seem that this slow and laborious method of irri- gation could be eliminated if the beds were prepared in a more up-to- date manner. The so-called spinach is not the plant which is recognized by that name in mainland markets, but is a species of Amaranthus. The leaves and stems of the young and tender plants, when properly cooked, make fairly palatable “ greens.” FOOD PLANTS AND INJURY. The most conspicuous enemy of this class of vegetables is the Hawalian beet webworm (Hymenia fascialis Cram.). In the Ha- walian Islands the larve of this species include among their food plants table beets, sugar beets, stock beets (mangel-wurzels), several species of Amaranthus, Euxolus, purslane (Portulaca oleracea), cucumbers, and chenopodiaceous weeds. Among the wild food plants; Amaranthus is the favorite. These weeds grow in abundance along fences and in neglected spots, and it frequently happens that the plants are so completely stripped of foliage that large patches of them die. Cultivated Amaranthus is likewise severely damaged. Beets are a close second in attractiveness, and it is not unusual to see beds of this vegetable with nothing remaining of the foliage but the petioles. When infestation is very severe the plants are oc- casionally killed outright, and even when the larve are less abun- dant the infested beets are stunted in growth and injured in quality. Sugar beets are attacked as readily as the table variety. During the latter part of August, 1910, the author received some sugar beets from the experimental plats on Lanai, from which practically all the foliage had been stripped, and it was reported that all the beets in the plats were in a similar condition. This webworm is the most serious insect pest which menaces the production of sugar beets in Hawaii, and unless it is controlled it is unlikely that this crop can be profitably grown. Cucumbers are apparently only rarely attacked and the occasional larve which were found infesting this cucurbit were doubtless feeding on it because more attractive food was not avail- able. Portulaca is commonly attacked but apparently is not so favored a food as Amaranthus or beets. | | THE HAWAIIAN BEET WEBWORM. 3 LIFE HISTORY AND HABITS. All stages of this pest can be found throughout the year. The moths (fig. 1) are usually to be found in abundance among the foliage of Amaranthus, beets, or other low-growing plants. During the day they remain concealed, usually on the underside of the leaves, but when dis- turbed they fly readily. They are but rarely attracted by lights. The scale-like iridescent eggs (fig. 2, a) are almost invariably deposited on the underside of the leaves. They are placed singly, in pairs, or in rows of five or more. On beet leaves, the favorite place for depositing eggs is along the midrib and larger veins. As many as 40 eggs, which had been deposited in the field under normal condi- tions, were counted on a single beet leaf. The eggs have been ob- Fic. 1.—The Hawaiian beet webworn (Hymenia fascialis); Female moth. Enlarged. (Original. ) served to hatch in 4 days. The young larve feed on the lower sur- face of the leaves. On beets, and probably on other plants, the larvee, except when nearly mature, consume only this surface. This: habit of remaining on the underside of the leaves, without eating through the upper epidermis, adds to the difficulty of successfully treating this pest with insecticides. (See larva and details, fig. 2, b-e.) In some cases the larve spin light webs, under which they rest. This web-forming habit is not very pronounced, and it is not unusual to find hundreds of larvee without any webs whatever. Under normal conditions the larve reach maturity in from 9 to 13 days. They then leave the plants, burrow slightly beneath the surface, and form firm, compact, oblong cocoons of webbed-together 4 INSECTS AFFECTING VEGETABLES. grains of earth. From the time of hatching until fully mature, the larvee are pale green, but while engaged in constructing their cocoons (fig. 2, h), they change to a reddish pink. They usually pupate about 2 days after entering the soil, and the adults issue from 7 to 13 days later, thus completing a generation in from 22 to 31 days. (See pupa and details, fig. 2, 7, g.) The climate of Hawaii is so equable that this pest is enabled to breed continuously, and it is possible that ten or twelve gen- erations might be produced an- nually. Owing to the overlap- ping of broods and to the fact that eggs, larve, pupe, and adults are to be found at almost any time, it is practically impos- sible to work out the number of generations for a given year from field observations alone.* Beginning in July, 1910, and continuing past the middle of January, 1911, the author reared this species through six genera- tions in the insectary. The rec- ords of five of these generations. are given below. The actual Fic. 2.—Hawaiian beet webworm: a, Egg on first (July-August) generation leaf; b, larva, dorsal view; c, larva, head Was reared from larve which and first thoracic segment; d, abdominal were collected in the field. and segment, lateral view; e, anal segment; f, 2 pupa, lateral view; g, cremaster; h, co- aS the egg stage was not ob- ROOM. «All exianees ek Osea tained the record is incomplete and is not included in this paper. For the sake of convenience the August-September generation is mentioned as the first, although, in reality, it was the second. The five following generations are in direct line of descent. FIRST GENERATION. August 20.—At this date four moths were collected in the field and confined in a cage. Ayenst 25. ee ee First eggs deposited. Amgust 29.0020 000 ee The eggs hatched. Bentember Too... ee First larve reached maturity. mentermber 9.00 First larvze pupated. memerber 16... ee First adults issued. 1It is not probable, however, that more than six generations can be produced succes- sively, beginning with one pair of moths, since insects in general, in the writer's experience, always undergo a resting stage—sometimes two.—F. H. CHITTENDEN. ie THE HAWAIIAN BEET WEBWORM. 5 From the above record the stages are as follows: Days Pa E ceemnetiay tea sv Sch oy Pll) oh ocho he, he ai Rigg ete et a aa eRe 208 8 ee ee eee RES ea. 4 NOPE Teeter eres oh SO i ac de I ene Se Bn ee Be Sip 3 Ua ae 2 fp gear NOS ie, IE ey Sa ee AES Res eg Nat hos, Ft, fe eae ToL) 22 SECOND GENERATION. Deeper POs ae its, isstied, a aS SO a Say FON pea eee First eggs deposited. E20 ee) Ai a ara He aS Sa ETS The eggs hatched. 0 a ee ee ____First larve reached maturity. EE PAI ee First larve pupated. _ LE TN ae 2 MSGS ERED ST First adults issued. From the above record the stages are as follows: ; Days a IN OD Dh a, GE oe re ae 4 IPERS ERNIE aw Line ey ee ee ek ee Beis QUES PGETEEeE Meer tnt ste ots IPR Eo ek eet 230" SIP SEM tS Are Sen els Rie at) dE ee ee i as al 27 THIRD GENERATION. SS ee a ne ae pope Sf Adults issued. eee peihcaetpe nul Mla ca First eggs deposited. 2 ap aa pepe The eggs hatched. 5 i eel lll ial le a ea seechentipt First larvee reached maturity. ummenamamermneit ans! eh tes EO Sel Ae First larve pupated. REI e SED inte, cee lak ee woe ob First adults issued. EI hats SI More adults issued. From the above record the stages are as follows: sit Days TE EE EEL UE PPE See me Me ae Vee ae mee 4 I ie ee Ae Pe te ON a EN ee ee ey 18 Eee aE IRIE I a RR TOS 0 NS NR. A i 9 eee rare Nee PRES Th Seat A ave tty weak Asya Wet gti n whe erty 26 Curiously enough the first moths, 10 in number, which issued No- vember 12, failed to deposit any eggs, so the first eggs deposited by moths which issued the following day (Noy. 13) were retained to commence the’ succeeding’ generation. FOURTH GENERATION. ; ' November Noe Seesaw ae epee ek oe a ult dssaeds ola) 3 fia ce MTU ies Pi ee ek First eggs deposited. ES REY Le a Ye Ce The eggs hatched. (NL eS es ER NSTC a a le a a a) ETA First larve reached maturity. LT ae A ne First larve pupated. eter eet ee. SO ee eee First adults issued. 6. INSECTS AFFECTING VEGETABLES. From the above record the stages are as follows: Days Wipe sige | bwevel Stnge 2. re 15 Papal Silage... -- <2 - - -- 8 e 12 Total... a rrr ee ene nt ol FIFTH GENERATION, December Li... eee eee Adults issued. December TO") 2 2 Se eee First eggs deposited. December 23__. 2. 2 ae eeee ee The eggs hatched. January 4_________-_________--45_22-___ a. 2 _ First Taye Treated eo JanvaryG 8 ee eee eee First larve pupated. Jantany 10. 9. een Lee ee eee First adults issued. From the above records the stages are as follows: Days LLG Be 1 5 a i A ee etc me ee Se 4 harval ‘stage... =. ee 14 Pupal. stage 2k ee ee A is Motal coe) oe a a These records were obtained in an open-air insectary at Honolulu. The moths were confined in open-wire cages, which contained an inch or more of moistened, sterilized soil. Beet or Amaranthus leaves, upon which the eggs were to be deposited, were placed in the cages and food was supplied the moths by putting in wads of ab- sorbent cotton, which had been saturated in molasses and water. This food was evidently greatly relished. The moths were very “wild” and flew about very actively whenever the cages were ap- proached. Copulation evidently took place at might, as during the several months that the species was kept under daily observation, in the insectary and field, no mating pairs were observed. Owing to the failure to obtain mating pairs and to the fact that it is difficult to distinguish the sexes when the moths are fluttering wildly about in the cages, no individual egg-laying records were obtained. In one case three newly emerged and unfertilized female moths were placed in a cage and supplied with molasses as food. They lived 10 days, and during this time deposited 300 eggs. Such a record is not con- clusive, but it indicates that each female is capable of ‘depositing at least 100 eggs. This is doubtless far short of the actual number of eggs that one female could deposit under normal conditions. THE HAWAIIAN BEET WEBWORM. 7 Temperatures at Honolulu during the time the specics was reared. Average | Minimum | Maximum | mean tem- | Month. tempera- | tempera- | perature ture: | ‘ture. for entire month. 1910. a SF". | =. rr . mri ‘Ate ‘ae a A oe oe & 1 * wy J hax? ft > an oe ee JSUT AIS se 2% pe Bee ‘ hey A Loe eee) By hay aia Sdn DS a eS ey ae, aie es i y ” — oe rth ot mite an “ees q ‘ ° yy NE ek ~ we aed Pay & is oe Lie te dee? Li We + . * ; 1? :* ; oa ha ure ry Oe ae | eg | ve a a Tee z ited = 2 weed eee ’ | fi o 4 » Y Aupyal Saree, Cee Sl Oe ee. oat wictiort. ihdet wetaaete hs er TES Tey Te + AROTT Ra ico fe etl hint ae al alk, Ome oe , ert ie we q = , ; “s ihe . nee aay dl nee dey " i’ down, Pree retac” 7s . , » \ ; Pet A.B. HM. Bul. 109, Part, 1V. ¥. Ck S..P. 11, April 5. 1912. PAPERS ON INSECTS AFFECTING VEGETABLES. | A LITTLE-KNOWN CUTWORM. (Porosagrotis vetusta Walk.) By F. H. CHITTENDEN, Sc. D., In Charge of Truck Crop and Stored Product Insect Investigations. INJURIOUS OCCURRENCE. During the past decade authentic evidence, based on specimens which have been reared to the adult, has been received of the in- juriousness of the cutworm Porosagrotis vetusta Walk., and com- plaints have reached the bureau of other cases of injury doubtless wrought by the same insect. * April 22, 1901, Mr. R. W. Caviness wrote from Southern Pines, N. C., sending numerous specimens of this cutworm, many nearly mature, with information concerning its ravages. His place at that time was described as literally alive with them, and there was an outbreak of the same species the previous year (1900), when it was impossible to get a stand of watermelons until the cutworms had matured. They seemed to eat “ every green thing.” Many cutworms were found on and about dewberry, sometimes a dozen or more to a vine. They crawled up the vines and ate the buds and leaves, and treated young peach and other trees in the same manner. It was impossible to get a stand of beans, cabbage, or any other garden “stuff.” They were described as most abundant and doing their _ worst damage on cowpeas. In 1900 they cut fall-sown turnips until _ .the weather became too cold for the larve to work. May 18 Mr. Caviness made another sending of this cutworm taken from melon vines, 100 having been caught in an hour’s time. They infested small vines that were just coming up, entirely destroyed one field of corn, and it was found necessary to replant both melons and _ corn. The land had previously been planted to cowpeas, but there _ Was no apparent reason why this crop had any influence on the 47 48 PAPERS ON INSECTS AFFECTING VEGETABLES. development of the cutworm except for some evidence that it might be a preferred food plant. The moths issued in our rearing jars during the first and second weeks of September, and conditions were such at that time that this is probably about the same period of issuance as that under natural conditions. In May, 1902, this cutworm was again very abundant in the same locality, particularly around watermelon hills. Our correspondent wrote further of this species and of a related form (probably the granulated cutworm, Feltia annexa Treit.) with which it was asso- ciated, that it had been a terrible pest in his vicinity during the two years previous, and that in 1901 the insects were notably more numerous than before. He stated that it would have been impossible to have grown a crop like cotton or tobacco on his place that year. Some of the larve were remarkably late in transforming to pupe, this being painfully evident in his melon field. No positive information concerning damage by this species was reported for a few years thereafter, but there can be no doubt what- ever that it was injurious, more or less, during many if not all of the remaining years. In 1908 this species was observed by Mr. C. H. Popenoe and the writer injuring kale, spinach, and lettuce in June at Norfolk, Va., where it was also associated in every instance of observed injury with the granulated cutworm (Feltia annexa). fs 3, 1909, near Poplar Branch, N. C., these cutworms were found by “Mr. W. L. McAtee, of the Biclowiag Survey of this department, to be exceedingly numerous in a ‘Tittle truck garden kept by Capt. J. T. Westcott. Single rakes of the fingers over 6 inches of the sandy soil disclosed from 6 to 12 cutworms. He gathered a quart of these for fish bait in a few minutes. Canta- loupe and watermelon vines were entirely defoliated and corn and tomatoes were slightly attacked. March 22, 1910, Mr. F. A. Johnston examined a field of about 3 acres of cultivated dandelions on the farm of Mr. Bruce Carney, at Churchland, Va., and found it badly infested with cutworms of this species. Hidden in the dead leaves around the base of some plants there were as many as 5 or 6 young larve. Some were quite small, and no appreciable damage had been done to the crop up to that date by this pest. The winter had been severe on the dandelions, most of them being killed back to the ground, but since the warmer weather set in the plants had made quite rapid growth and were in very fair condition. The crop was being cut for market and it seemed quite probable that a thorough spraying of the leaves that remained after the crop was harvested with either arsenate of lead or Paris green would control the pest. A LITTLE-KNOWN CUTWORM. 49 Some of the larve obtained from this source were kept for rear- ing in this bureau. The first adult issued May 20, and others trans- formed to moths September 15 and 20. During the first days of September, 1910, in an extremely heated spell, this species attracted attention on the farm of Mr. B. C. Haines, near Shelton, Va. Mr. Haines was advised to use arsenate of lead at the rate of 4 pounds in 50 gallons of water, and when the writer visited the infested locality a few days later he found that this remedy was producing excellent results. It should be mentioned that on Mr. Haines’s farms truck plants are grown in alternate years, so as to produce four alternate crops. In this case parsley, growing between rows of lettuce, was badly affected. As soon as the lettuce was cut for market parsley began to appear and was cut off by the worms even with the ground, so that only a few plants could be seen here and there. The farm is being conducted by irrigation, both overhead and by means of hose, and it is probable that the prompt success in the use of arsenate of lead was doubtless due to the fact that the insects were watered, and thus cooled, at night and heated again by the extremely hot weather occurring during the day. It was found impossible to trace the occurrence of this species earlier in the season, and it was finally agreed between Mr. Haines and the _ writer that in all probability the cutworms had been introduced with stable manure grown up freely with grass and weeds which had been used when the lettuce and parsley were first planted. They could not have come from any outside source or from any earlier crop. The success of Mr. Haines in his treatment of this pest is shown in the accompanying abstract from his letter. RESULTS FROM APPLICATIONS OF ARSENATE OF LEAD. NoRFOLK, Va., November 18, 1910. I received your letter of the 16th instant, in regard to the cutworms on my parsley and the ravages of the army worm in this section this fall. As you remember, I had a hard fight with the cutworms on my parsley field, but I feel fully compensated for my work and expense in fighting them. I had several places in each bed where I had to reset plants where the cutworms cut them off, but aside from those few spots I have a perfect stand and am now marketing my crop, and I wish you could see that crop. The best out- look I have ever had. I kept constantly spraying my parsley with arsenate of lead (4 pounds to 50 gallons of water), and in all I think I gave it five applications. * * * B. ©. HAINES. It should be added to the above that a careful survey of the in- fested field by the author showed plainly that an arsenical was the only remedy that could be conveniently used after the outbreak was at its height. It should be added also that the arsenate of lead was not applied five successive times on the same plants. 50 PAPERS ON INSECTS AFFECTING VEGETABLES. DESCRIPTION. The moth.—The moth of this species is quite unlike any common form which inhabits the North Atlantic region, being much paler in color. The forewings are gray, with a pinkish tinge in fresh speci- mens. There is a submedian dark spot and a row of spots in the form of a curve in the outer third of the wing. The markings are well illustrated in figure 8 (above). It will be noted that the hind- wings, which are silvery whitish and are more or less tinged on the outer edges with gray, are considerably shorter. The thorax is of about the same color as the fore wings and nearly uniform through- out. The anterior portion of the abdomen is white and the posterior portion, sometimes a little more than half, is gray. The lower sur- face is pale, with the fore wings more or less suffused anteriorly with fuscous. The posterior legs are distinctly tessellated. The abdomen is rather more robust than in many related forms, being narrower in the male. The wing expanse is 14 inches and_ the length of the body is about five-eighths of an inch. The eggs and ear- ler stages of the larva have not been studied to the writer’s eae knowledge. Fic. 8.—Porosagrotis vetusta: Moth and larva. The ltarva—tThe larva is subject to considerable variation, which may be dependent on the soil. Speci- mens received from North Carclina, in a very sandy soil, are pale, with a decidedly pinkish tinge. The arrangement of the tubercles is shown in figure 8, as is also the form of the thoracic plate. The larva, when alive and when fully matured, measures about 14 inches, but the inflated specimens run as high as 2 inches in length. No specimens of the pupa have been preserved for description. DISTRIBUTION. All of the specimens of this species in the United States National Museum are from New York State, and are labeled as follows: Albany, Long Island, Carver, Rochester, and Franklin County, ‘ibe There are also specimens of what appear to be races of this species, one of them being labeled Porosagrotis satiens, from Coleville, Wash., Glenwood Springs, Colo., and from Arizona, and a second A LITTLE-KNOWN CUTWORM. 51 species labeled P. catenula Grote, from Los Angeles, Cal., Glenwood Springs, Colo., Phoenix, Ariz., and Kaslo, British Columbia. We have reared Porosagrotis vetusta, which displays only slight variation as compared with many other forms of cutworm moths, from Shelton, Churchland, and Norfolk, Va., Rocky Ford, Colo., and Southern Pines, N. C. Another locality is Poplar Branch, N. C. In 1895 Slingerland? mentioned this species in connection with other climbing cutworms under the name of the “ spotted-legged' cut- worm,” stating that it occurred in Erie, Lewis, and Monroe Counties, N. Y. Less than 2 per cent, however, of the climbing cutworms received from western New York in 1893 and in 1894 belonged to this species. Beyond the fact that it was found on peach buds, noth- ing was then known of its habits. The larve and moth were figured. NATURAL ENEMIES. This species no doubt has many natural enemies. The following, however, are the only ones at present known, both being parasitic: Apanteles n. sp., near agrotidis, issued from larve of this cut- _ worm received from North Carolina, May 18, 1901. Determined by _ Ashmead. Linnemya picta Meig., a tachina fly, issued from the second lot, from North Carolina. It was identified by the late D. W. Coquillett. _ The same species of tachina fly was reared from this cutworm from material received from Norfolk, Va., the flies issuing October 8, 1910. 1 Bul. 104, Cornell University Experiment Station, pp. 570-571. HIS PUBLICATION may be pro- cured from the Superintendent of Documents, Government Printing Office Washington, D. C., at 5 cents per copy at ithe ieee a is oe te wh 3) 3 fore9%s 3 * i " =< j Ls 2 ‘ae eS te 4 ‘ 2 54 4 Sa SB te ae Si - ¢ < 4, e iC 4.% > ; { ; ote v , d , ey y 5) oe eS “és a Aeh i pat egrt FS . Lf i ‘ ; , ime Lit Bier. | apt ‘pit Lovaiqoe ard f y TL tif. Taro AO { Ji iS + he I's J "4 2. _ S z P ® « 2 * ¥ Th Attaobaeee, See the 3 3. ‘ *: oF * 5 : Py a > £4 LTRS L. $i J yotle a BT b a 4 . me j ‘ } ¢ { 4 44 bit oe a Lee : | apt Est? Pyne te ee Sainten d faa STAN - aa we 4 z i \ af 340 ; Fi i i ~F = 7 TS , ft ry (Th en a wT: f ¢ a ; 0 ks 4 ¥; i. Se q! ( : Lyi pies & a ee ’ i % a * ue ’ 7 at * 4, ~ if ‘ i? Ss e oaks ed ToD % at bre M it an. , : << 4 P ‘ ~~ - : ners \ 4 j : eH Hy SUVs, Sv atees-. ea Se! pe il a ee Ph 2 amt eS ‘3 | “| ath; - i wh . -. Sin ee ee ee ee Bae te concen emis ‘gn ee ie = ™ aa Dae. et mS ew, ‘i Pe mn » is * io Ore wel see he Soiree cs reid i (Petes . 2 : i 3 a - ‘ F as a hae CAT © ee : : =e Tre 5 \. ~ - ‘ ~~ ae » = | ee 1 i, ? eto ere = j —-_ cy Pigs | SS eee ee ee ee he “ Bape thie 7 iil ee DK BHEX) G& 32 5 A OTT ‘sat ye ee Oe me Of SOR> Seas 11 Me ENS 6, Péoreatavovtie eet, Teal ¢ Cri sty from (Av teas, age a . a ee ae te Je 4S = ‘ : * i a < a e.-5. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 109, Part V. L. O. HOWARD, Entomologist and Chief of Bureau. PAPERS ON INSECTS AFFECTING VEGETABLES. _ ARSENITE OF ZINC AND LEAD CHRO- MATE AS REMEDIES AGAINST THE COLORADO POTATO BEETLE. BY FRED A. JOHNSTON, Entomological Assistant. [In cooperation with the Virginia Truck Experiment Station.] IssurepD APRIL 5, 1912. WASHINGTON: 21213 Ab GOVERNMENT PRINTING OFFIOE. 1912. eS ee eee eee oe ee BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Maruatr, Entomologist and Acting Chief in Absence of Chief. R. 8S. Currron, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. CuirreNpDEN, in charge of truck crop and stored product insect investigations. A. D. Hopxins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. WEBSTER, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, tn charge of deciduous fruit insect investigations. EK. F. Pures, in charge of bee culture. D. M. Rocers, in charge of preventing spread of moths, field work. Routa P. Curris, in charge of editorial work. MaBEL CoucorD, in charge of library. Truck Crop AND STrorRED PrRopuct INsEct INVESTIGATIONS. F. H. CutrrENDEN, in charge. H. M. Russet, C. H. Popenor, Wm. B. Parker, H. O. Marsa, M. M. Hien, Frep A. JoHnston, JoHN E. Grar, entomological assistants. I. J. Conpir, collaborator in California. P. T. Cos, collaborator in tidewater Virginia. W.N. Orp, collaborator in Oregon. Tuos. H. Jongs, collaborator in Porto Rico. Marion T. Van Horn, Pavutine M. JOHNSON, preparators. iL C.O Na TN ES Ga , Page. experiments with arsenite of zinc and lead chromate in comparison 53 55 III ss en a keSs shies PA S8 sa reg ate! E Avett ‘he: A Paes * Sue , 2° P a PAARL UAT AS SHA ARG 6. ARES tee tortie. Broattts Wap ach Boye i y i vee, . . wer f eV ant . : ua . ¢ * : ew hx : e © i¢ 44 ee el dee), Card an b : = \ (‘eMart ct ities bet bake Sata iy tiersees Habe se M Lae he Ohl ; oy -eftecees: taowirh Fe cae, lo Sthapeial baie oF wisi Pe SRW Cheese ae * e U.S. D. A., B. E. Bul. 109, Part V. Pees. Fe April &,, 1912. PAPERS ON INSECTS AFFECTING VEGETABLES. _ARSENITE OF ZINC AND LEAD CHROMATE AS REMEDIES AGAINST THE COLORADO POTATO BEETLE. By Frep A. Jounston, Entomological Assistant. [In cooperation with the Virginia Truck Experiment Station.]} SPRAYING EXPERIMENTS WITH ARSENITE OF ZINC AND LEAD CHROMATE IN COMPARISON WITH OTHER ARSENICALS. In May, 1911, a series of experiments for comparing the insecti- cidal value of peearie of zine and of lead chromate with that of other arsenicals in controlling the Colorado potato beetle (Leptinotarsa _decemlineata Say) was undertaken under the direction of Dr. F. H. Chittenden at the Virginia Truck Experiment Station, at Norfolk, Va. The season was later than usual, making it unnecessary to spray for the potato beetle until about May 9. At this date no larve were _ present on the plants, though beetles and egg masses were abundant. On May 9 six plats were sprayed. Table I gives the insecticides and strengths used. Tanur I.—Sprays used against the Colorado potato beetle, Norfoik, Va., May, 1911. aay Insecticide used. I | Lime-sulphur, 2 pounds to 50 gallons of water and 3 pounds of arsenate of lead. If | Arsenate of lead, 3 pounds to 50 galions of water. _ U1 | Lead chromate, 2 ounces to 4 gallons of water. _ IV | Arsenite of zinc, 13 pounds to 50 gallons of water. V | Bordeaux mixture (4-6-50 formula) and 14 pounds of Paris green. VI | Bordeaux mixture (4-6-50 formula) and 13 pounds of arsenite of zinc. _ On May 22 all of the potatoes were resprayed, the same proportions of the different materials being used with the exception of the lead _ chromate in which case the strength was doubled. (One ounce to a gallon of water.) At this date the larve were exceedingly numerous and doing much _ damage in unsprayed potato fields. ; 21142°—12 53 54 PAPERS ON®INSECTS AFFECTING VEGETABLES. On the day following the second application of the sprays a count of the infested plants in each plat was made and the following figures obtained: TaBLE I].—Results of spray applications against the Colorado potato beetie, Norfolk, Va., May, 1911. ’ No. Insecticide used. fested fested tion plants plants Per cent I | Lime-sulphur (2-50 formula) and 3 pounds of arsenate of lead.....-. 37 347 ; II | Arsenate of lead, 3 pounds to 50 gallons of water...............-.-.- 118 622 15.93 III | Lead chromate, 2 ounces to 4 gallons of water, and 1 ounce to 1 gal- lon of water...-. ET a eA ey ANT oa DBD 216 169 +56.0 IV | Arsenite of zinc, 14 pounds to 50 gallons of water.................-.- 206 1,048 16.4 V | Bordeaux mixture (4-6-50 formula) and 14 pounds Paris green. .... 152 741 +17.0 VI | Bordeaux mixture (4-6-50 formula) and 14 pounds arsenite of zinc. . . 225 555 28.8 It will be seen that the results obtained from the use of lead chromate were very unsatisfactory as compared with those in the case of other insecticides used. The lead chromate employed was in the form of a powder, and great difficulty was experienced in making it mix well with water, it having a tendency to settle quite rapidly, requiring constant agitation to keep it in solution. It adhered well to the foliage, and its color stood out quite prominently in contrast to the other plats. However, the young larve seemed to be able to feed on plants that were thoroughly covered with the material without receiving much 1 injury. The arsenite of zinc employed was also in the powdered form. bi is much lighter than lead chromate and remains in suspension in water much better. It adheres to the foliage very well and does not, so far as could be observed, burn or injure the plants in any way. The percentage of infested plants in the plat that was treated with Bordeaux mixture and arsenite of zinc was somewhat greater than in the plat in which the arsenite of zinc alone had been used. _ This was no doubt due partly to the fact that the Bordeaux-arsenite of zinc plat was in a different field, one which had been in potatoes the previous year and was thus subject to the attack of a greater number of beetles. Also, many of the plants which were counted as infested were only slightly injured, and it is doubtful if the yield of potatoes would have been much lessened. « On June 29 the potatoes were dug, and following are the weights of one row of potatoes in each of the first four plats. = Situ (oe ARSENITE OF ZINC AGAINST POTATO BEETLE. Did TasBLeE III.— Yields of potatoes from one row from each of Plats I, II, III, and IV, sprayed as indicated in Table I. One TOW Number} Weight | Weight from Insecticide used. of plants | of No. 1 | of No. 2 plat in row. | potatoes.!| potatoes.? No. Pounds. | Pounds. Tel Phime-saiphur and arsenate of lead... 2.2222 -552-.5- 2. e dees ese n 384 1884 25¢ Wi errserane Olea ee) ioe soak os coe. oo oo OREN Pee see 368 1722 | , 26 MIME CCRC MOM ALC a: se a) ace ee ook oe ee ne Ae go aweseee see 385 128 193 See SCMILC OL ZING. ==... PP oe see Se US Ca cincickes os ceeds Deas oee 374 143% 18 1 Excellent to good. 2 Fair to indifferent. By taking the yield of the same number of plants from each row the contrast between the different rows will be more marked. Table IV represents the yield of 374 plants from each row: Taste IV.— Yields of potatoes from 374 plants from one row from each of Plats I, II, ITI, and IV, sprayed as indicated in Table I. od One 4 TOW : Number | Weight | Weight from Insecticide used. of plants | of No.1 | of No. 2 plat ’ in row. | potatoes.1| potatoes.2 No Pounds. | Pounds. me anmae-cmlonir and arsenate of lead. ...=----.-----+----22-2--265- 374 | 183. 26 25. 05 Men Suse Ormeatett eae 565.8 Sas Sig: Sees). oe Seek lee 374 | 175. 401 26. 18 MING HEREIN AL Gere eos cee cs aces ct ol ha Taegu ee sees laws s seis aid 374 | 124.168 19. 07 LY Uh RATES STIS) Ty WA) eS ee ea ee 374 | 143.5 18 1 Excellent to good. 2 Fair to indifferent. SPRAYING EXPERIMENTS WITH ARSENITE OF ZINC AT VARIOUS STRENGTHS. An experiment with the three following strengths of arsenite of zinc in controlling the Colorado potato beetle was begun at the Vir- ginia Truck Experiment Station, Norfolk, Va., on May 31, 1911. No. I, arsenite of zinc, 1 pound to 50 gallons of water. No. II, arsenite of zinc, 14 pounds to 50 gallons of water. No. III, arsenite of zinc, 2 pounds to 50 gallons of water. On the day the spraying was done (May 31) the rows sprayed with No. I, No. II, and No. III had 47, 86, and 88 infested plants, respec- tively. On June 2 the row treated with No. I had 33 infested plants, a decreased infestation of 14 plants, or 29.8 per cent. The row treated with No. II had 57 infested plants, a decreased infestation of 29 plants, or 33.7 per cent, while the row treated with No. III had 38 infested plants, a decreased infestation of 50 plants, or 56.8 per cent. 56 PAPERS ON INSECTS AFFECTING VEGETABLES. On June 3 the count was again taken, and the row treated with No. 7 I had 15 infested plants, a decreased infestation of 32 plants, or 68+ per cent. The row treated with No. II had 23 infested plants, a decreased infestation of 63 plants, or 73.2 per cent, while the row treated with No. III had 13 infested plants, a decreased infestation of 75 plants, or 85.2 per cent. The following table shows the number of infested plants in the plats before and after spraying: TaBLeE V.—Results of applications of arsenite of zinc at different strengths against the Colorado potato beetle. -| ' : Decrease in | Solu- | umber of | number of | Decrease of Date. | tion [init infest infesta- No. | plants plants. | — | | 1911 | Per cent Miry Sin ro. 2 oon ae etn | eg eee - ee oe I 47 ) af I EY 3 | bs As Seeded DO... 226 dennn a= -s6n- oh Be oe Se cage Ae ae II 86 |. ... 2005 ..oe eee DO 2525 CE Eee. a ee a ee iil 88. |. -- 32). =. Soe Sie eee PP Sch a ok a pe ee ee I} 33 14 29.8 DOs 5 Le. es as ee et ee Se II |} 57 29 33. 7 hie ARREARS GAS Ss Siena wad «eins. 11 | 38 50 56.8 PGS. 2b RE . OS oS sr 3. eh ee ES 15 32 68+- Ot 5. be OL. SSUES sass oe es chee eee II | 23 63 73. 2 We ES ea, se ER aes ass Se oe SR RSE IIT | 13 75 85. 2 On June 3 the number of larve on the plants which were still infested was much smaller than the number present when the spray was first applied. The extent of infestation of some plants amounted to but one or two larve; these plants, however, were counted in as’ infested. | Results——From the preceding table it will be seen that far better results were obtained where 2 pounds of arsenite of zinc to 50 gallons © of water were used. The results were obtained more quickly, and a larger percentage of larve was killed. At this strength arsenite of zine did not burn or — injure the foliage in any way, and without doubt an even greater amount of the arsenical might be used without injury to the plants © and with correspondingly greater efficiency in killing the beetles. Aare COPIES ofthis publication may be procured from the SUPERINTEND- ENT OF DOCUMENTS, Government Printing Office, Washington, D. C., at 5 cents per copy Peo DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 109, Part VI. L. O. HOWARD, Entomologist and Chief of Bureau. PAPERS ON INSECTS AFFECTING VEGETABLES. THE SUGAR-BEET WEBWORM. ke 2 eae, - 1 BY H. O. MARSH, Entomological Assistant. IssuED SEPTEMBER 16, 1912. ~sonian Insti, Zag Instituyg SAAS i ‘ } WASHINGTON: GOVERNMENT PRINTING OFFICE. 1912, e s ~~ , 7 ’ * —— sie: -_y >t BUREAU OF ENTOMOLOGY. L. O. Howarb, Entomologist and Chief of Bureau. C. L. Marratr, Entomologist and Acting Chief in Absence of Chief. R. S. Ciirton, Executive Assistant. W. F. Taster, Chief Clerk. F.. H. CHITTENDEN, in charge of truck crop and stored product insect investigations. A. D. Hopkins, in charge of forest insect investigations. W. D. HUNTER, in charge of southern field crop insect investigations. F. M. WEBSTER, in charge of.cereal and forage insect investigations. A. L. QUAINTANCE, in charge of deciduous fruit insect investigations. E. F. PHILLIPS, in charge of bee culture. D. M. Rocers, in charge of preventing spread of moths, field work. Rouiia P. CurRi£, in charge of editorial work. ; MABEL COLCORD, in charge of library. TRUCK CROP AND STORED PRoptct INSECT INVESTIGATIONS. F. H. CHITTENDEN, in charge. H. M. RvuSsSsELL, C. H. PoPENOE, WM. B. PARKER, H. O. MarsH, M. M. Hieu, JoHN E. Grar, Frep A. JOHNSTON, entomological assistants. I. J. Conpit, collaborator in California. W. N. Ord, collaborator in Oregon. THos. H. Jones, collaborator in Porto Rico. Marion T. VAN Horn, PAULINE M. JoHNSON, ANITA M. BALLINGER, preparators. If CON EE NTS: MT Meer NRIAB Ee cw) MP Re I yee tg BRET 6) IO AP ne te General appearance of the sugar-beet webworm and nature of attack......... SR SMT LS Sut 0 FE a a ae en Lee AO Ty a SE REL TL) LP RRR RSIS TRIS IO ee eg oe NO RT al RAG On RE ek hh el Oe OS Fk ee ‘bis PA ee ae ge es ghey 0000 c) ai CNIS Be ei anti Mcrae yo umenrieunemnmnihinromedias. 8.6.7.2 ek lane sai lac. TLE TE CI G7 Se ae ere eT TT A ee 2 NEE Atel et a nh ee ae oe Fic. 9. 10. el V2: 13. 14. 15. 16. 7. 18. 19, 20. 21. 22. 23. Pao hia PON S. The sugar-beet webworm (Loostege sticticalis): Moth.............-.--- The garden webworm (Lozostege similalis): Moth, larva, pupa, details. A medium-sized sugar-beet plant defoliated by the sugar-beet web- “OSLTLL Ln) Ue Shs ote Sane dee ek a orn eee mA Sugar beets defoliated by the sugar-beet webworm in July......--.... Large sugar-beet plants, showing defoliation and weakened roots due to attack by the sugar-beet webworm in August............-.- Field of young sugar beets destroyed by the sugar- flea oa oS in Tu une. Barrel sprayer suitable for use against the sugar-beet webworm... Barrel sprayer in action against the sugar-beet webworm.........-.-.-- Houm-row attachment for beet sprayer. ..-.2-.--.2-\4. 2. 22.-4---52-22-- Heurrow attachment for beet sprayer. ....-.--.) 222-202. sess bet ee Hour-row attachment for beet sprayer. ....:.-.../2------5-5-224-.5-- Geared traction sprayer suitable for use against the sugar-beet web- Geared traction sprayer in action against the sugar-beet webworm. .- - Filling a traction sprayer for spraying against the sugar-beet webworm. . Type of Vermorel nozzles suitable for spraying sugar beets against the See MeL WemmOnlite sts 4. sk Tole e lS Bates t cee ed See EEE UN eee 2 * r Pine " ' arte , 1 ¢ 4 ‘ t ' ‘ \ i oan f # f . ‘iy I . \ Je ; 4 ] yg ad ' f i VEE F } sl 1 > ech + . \ Bes UP si The. al y : ; 4? ‘= * ps 2 7 \ . Ps = j - ‘ ! i 3 . . ’ y we _— = nese eee ee, Te Ch = > ao ie), i w. S: D. A., B. E. Bul. 109, Part VI. T. C. & S. P.-I. I., September 16, 1912. PAPERS ON INSECTS AFFECTING VEGETABLES, | A REPORT OF PROGRESS REGARDING THE SUGAR-BEET WEBWORM. (Lozxostege sticticalis L.) By H. O. MarsuH, Entomological Assistant. INTRODUCTION. During portions of the years 1909 and 1910 and nearly all of 1911 the writer, stationed in the Arkansas Valley of Colorado and Kansas, was engaged in a study of the insects affecting sugar beets and truck crops. Among the foremost of the species of insects studied was the sugar-beet webworm (Lowostege sticticalis L.). Although the investigation of this pest has not been completed, control measures have been fairly definitely worked out, and this preliminary article is presented with the hope that it will stimulate greater interest in the subject among the beet growers, and thus render the os of the study more easily accomplished. Sugar beets have been produced on a commercial scale in the Arkansas Valley since 1900, and almost from the beginning this crop las been infested by webworms. The injury produced by these in- festations has varied greatly from year to year. During some seasons little noticeable damage has occurred, while on a few occasions the infested acreage has been extensive and the losses serious. As an example it may be mentioned that in 1910 practically 4,000 acres of beets grown for one of the sugar factories in the Arkansas Valley were attacked. The serious nature of this outbreak was not realized until too late, and although strenuous efforts were finally made to control the “ worms,” the loss resulting from this infestation was esti- mated at 20,000 tons of beets, which would have been worth approxi- mately $100,000 to the growers. Such severe losses are rather excep- tional, although nearly every year the loss occasioned by webworms is far in excess of the amount imagined by the average beet grower. To the progressive farmers in the Arkansas Valley the sugar-beet webworm is generally too well known to require a detailed descrip- tion, although a few notes regarding the life history when infesting sugar beets may be of value. | ot 58 PAPERS ON INSECTS AFFECTING VEGETABLES. GENERAL APPEARANCE OF THE SUGAR-BEET WEBWORM AND NATURE OF ATTACK. The parent of this webworm (fig. 9) belongs to the lepidopterous family Pyralide, and is a tawny-brown, active moth, or “ miller,” with a wing expanse of about 1 inch. It is larger and more conspicuously colored than the garden web- worm which is shown in figure 10. The moths deposit their pearly-white eggs singly or in rows of from two to five or more, usually on the under side of the leaf. When deposited in rows they overlap more or less. Each female moth is capable. under normal condi- tions, of depositing at least 200 eggs. From these eggs hatch the small larve, Fic. 9.—The sugar-beet webworm oe ‘ es When — abe (Loxostege sticticalis): Moth, * Worms” are whitish, with black heads, eee te aes (Reengraved but as they feed and increase in. size eit they become green, with dark markings. The very young larve eat small holes in the under side of the leaves without, however, cutting through the upper epidermis, but as they increase in size they consume almost the entire leaf, with the excep- tion of the larger veins and the petioles. The “worms” prefer the older leaves, and unless the food supply is nearly exhausted do not eat the young leaves at the center of the plant. When full grown the “worms,” which are slender and about an inch in length, leave the beets and burrow in the soil, usually close about the infested plants, and spin tubelike cases in which they later pupate. Fic. 16.—The garden webworm (Lozostege simi- The pupe are slender, lt) ,¢ ale mot: larva, lateral lem vellow-brown, Inactive ob- segment, lateral view; f, pupa; g, cremaster. : a : : a, b, c, f, somewhat enlarged; d, €, g, more en- jects, from which during larged. (After Riley, except c, from Chittenden.) the summer months the moths issue within a few days. The moths, after issuing, feed on the nectar in alfalfa or other blossoms and within a few days mate and are ready to commence depositing eggs for another generation or brood of “ worms.” oe, ee, ee > “ ao Cee eS eS ey eer ee i ct, Se feat ee PROGRESS REGARDING SUGAR-BEET WEBWORM. 59 LIFE HISTORY AND HABITS. In rearing experiments conducted at Rocky Ford, Colo., the average time required from the deposition of the eggs until the moths issued was a little more than a month. The egg stage was observed to vary from 3 to 5 days, the larva stage from 17 to 20 days, and the pupa stage was usually 11 days. These variations were from records of successive generations. So far as the writer has been able to determine, there are three generations or “crops” of webworms in the Arkansas Valley each year. There may be a fourth generation, but if so it is not clearly marked and possibly occurs early in the season on weeds such as Russian thistle (Salsola tragus) and lamb’s-quarters (Chenopodium album). For the sake of convenience we may assume that only three generations occur yearly. The periods during which the writer ob- served the webworms of these successive generations in evidence on sugar beets in the Arkansas Valley ranged from about the middle of June until early July for the first generation and from about the middle of July until well into August for the second generation, while the third brood occurred in September. In reality the generations are not sharply marked and considerable overlapping may occur. In general the danger period extends from shortly before the middle of June until well into September. The first generation of webworms may be expected at its height of destruc- tiveness during the latter half of June, at a time when the beets are comparatively small and least able to resist the attack. (See fig. 14.) At this season the infested beets may actually be killed by this webworm, which, after eating all the leaves, may destroy the crown of the plant. Whenever the crown is destroyed the beet dies. So far as the writer has observed, the acreage destroyed in this way is very small and ordinarily occurs only when the infested beets are young and the available leaf surface limited. By the time the “worms” of the later generation are present the beets have become of good size and, although they may be completely stripped of all but the youngest leaves, it is rarely that any are killed. (See figs. ot, 12.) | The larve of the first generation, after maturing and burrowing into the ground, pupate promptly and the moths issue within a few days and deposit eggs for the second generation. The “worms” of this next generation, on reaching maturity, likewise burrow into the ground and spin their tubelike cases. However, only about half of them pupate promptly, the others remaining unchanged in the tubes until the spring of the following year. From the pupe which develop in August, moths issue which deposit eggs for the third or September generation, and these “worms” remain unchanged throughout the. 60 PAPERS ON INSECTS AFFECTING VEGETABLES. winter. It will thus be seen that about half the webworms of the second generation and all of those of the third generation, which have not been destroyed by parasites or through artificial or natural agencies, live through the winter in their tubes in the soil. These “worms” pupate late in the spring and the moths which issue deposit eggs for the first generation. i The moths when depositing eggs are often to be found in the beet fields in enormous numbers, and when disturbed may be seen flying close above the beet leaves in “ clouds.” When such numbers of moths are observed in a beet field they should serve as a warning to the Vic. 11.—A medium sized sugar-beet plant defoliated by the sugar-beet webworm in July. (Original. ) grower that a “crop” of webworms may be expected within the next week or 10 days. As a rule the first and second generations are the most destructive, the third generation, which is actually only a partial one, rarely ‘ausing serious damage. It seldom happens that the “worms” of successive generations infest the same patch of beets to a serious ex- tent. Thus a certain field may be infested by the webworms of the first generation, while the moths which develop from them may drift to adjoining fields to deposit eggs for the next generation. The webworms often appear very suddenly and apparently with- out warning in certain fields, and it is not uncommon for the growers to express the idea that they have migrated from adjoining fields. food. = 8 aes ee Sree Fee Te ee ee injury depending on the present, the size of the _ infested beets, and various _ other factors, such as cli- - matic conditions, soil fer- tility, and water supply. _ As previously mentioned, _ outright (see fig. 14), while larger beets may aa be completely stripped Fic. 12.—Sugar beets defoliated by the sugar-beet PROGRESS REGARDING SUGAR-BEET WEBWORM. 61 This, however, is not the case, but their apparently sudden appear- ance is explained by the fact that the young webworms are easily overlooked and that during the last few days before they reach maturity their growth is very rapid. It frequently happens that from 50 to 300 eggs are deposited on single beet plants, and in ex- treme cases as many as 500 eggs may be so placed. The worms hatch- ing from these eggs remain upon the beet on which they hatched until they reach maturity, unless all the leaves are destroyed and they are thus forced to crawl to another beet to obtain CHARACTER OF INJURY. It is impossible to state definitely the damage to sugar beets that an infes- tation of webworms may cause, as this may vary from almost no percepti- ble loss to the ccmplete destruction of the infested plants, the extent of the number of webworms small beets may be killed = A webworm in July. (Original.) of foliage. With large _ beets new leaves will usually be put out promptly and _ their _ apparent recovery will take place quickly, especially if they are - irrigated as. soon as possible after the defoliation. Although new _ leaves are soon put out, defoliation retards the growth of the beet _ roots. (See fig. 13.) The writer has seen beet roots which at the __ time the tops were defoliated, in early July, were more than an inch _ in greatest diameter that mane absolutely no gain in weight or _ size for three weeks after the leaves were ed ibe ene be ; added that these beets were in good, fertile soil and were watered 51094°—Bull. 199. pt 6—12——2 62 PAPERS ON INSECTS AFFECTING VEGETABLES. even while the webworms were destroying the foliage. Judging from personal observations and from the statements of many growers, the writer may state that when sugar beets have been defoliated by webworms during the growing season a loss of from 1 to 5 tons of roots to the acre may be apparent at harvest time. The decrease in tonnage is not the only damage, as analyses of such beets have indicated losses of both sugar content and purity, which in some cases have reduced the price $1 a ton. Another injurious feature which follows defoliation is that the soil about the beets is exposed to the direct rays of the sun, allowing the moisture to evaporate rapidly, and if the supply of irriga- tion water is limited this may become a seri- ous matter. It will be seen that the sugar-beet webworm is a pest capable of causing extensive dam- age and that. measures tending toward its con- trol are worthy of care- ful consideration. NATURAL ENEMIES. Fortunately this spe- cies has natural ene- mies, among the most blackbirds. These birds often gather in enor- Fic. 13.—Large sugar-beet plants, showing defoliation MOUS flocks in the in- and weakened roots due to attack by the sugar-beet fested beet fields and webworm in August. (Original.) feed on the webworms. Unfortunately the webworms are not thus attacked until they have become nearly full grown and attain a size that renders them more conspicuous. Asa result, it generally happens that the infested beets are partially or completely defoliated before the birds have com- pleted their good work. The destruction of the “worms,” however, lessens the possible number of the succeeding generation. The web- worms are also reduced in number by true parasites, and in some cases the writer has found fully 50 per cent of the overwintered larvze killed in this way. One of the most common parasites is a little wasplike insect known scientifically as Diosphyrus vulgaris Cress., a braconid. efficient of which are. —————— eS PROGRESS REGARDING SUGAR-BEET WEBWORM. 63 OTHER CHECKS. As previously noted, the webworms burrow into the soil about the infested plants, and when the beets are plowed out at harvest time many of the worms are crushed or are so deeply buried that the moths, if they succeed in developing, are unable to leave the tubes, and consequently perish. In spite of these checks there will be every year some areas of greater or less extent where the web- worms will occur in injurious numbers and where spraying or. other artificial control measures will be necessary. Fic. 14.—Field of young sugar beets destroyed by the sugar-beet webworm in late June. (Original. ) EXPERIMENTS WITH REMEDIES. During the time the writer has been stationed in the Arkansas _ Valley he has given special attention to means of controlling this _ webworm, and in his opinion spraying with Paris green has proven made many experimental tests with a variety of insecticides and _ has also supervised a considerable amount of practical work against -tormulas as most efficient: . : Formula No, 1. oe UE Sit as Fees ee eee eck ae ey ae OE pounds__ 38 reemerged A ols del 6 (SET a RES NE Et i OREO eS OES FR Ne gallons__ 100 Formula No. 2. oT EE Ss eee pounds... 3 Lk we abt te a a ee ee wy SB EE i gallons__ 100 64 PAPERS ON INSECTS AFFECTING VEGETABLES. These mixtures have been appled to sugar beets with various types of sprayers (figs. 15-22) at the rate of from 80 to 125 gallons per acre, and the results have been uniformly successful in controlling the web- worms. As a rule, 100 gallons per acre should be applied and the spraying commenced as soon as possible after the webworms have > hatched. Where possible the spray should be applied at about 80 pounds pressure, although the writer has observed good results where only 40 to 50 pounds pressure was maintained. The leaves of sugar beets are quite smooth, and in order to apply an even coat of poison it is necessary to add some adhesive to the spray mixture. In the writer’s experience nothing has proven more satisfactory for this I'1G. 15.—Barrel sprayer suitable for use against the sugar-beet webworm. (Original.) purpose than whale-oil soap. If it is not obtainable, ordinary laun- dry soap may be used with about equally beneficial results, although it is more expensive. Lime, as recommended in formula No. 2, serves to an extent as an adhesive and has the additional effect of neutraliz- ing any free arsenic which may be present in the Paris green. Lime, however, renders the mixture somewhat caustic, and this formula is less pleasant to use than is one in which soap is used as the adhesive agent. Refuse molasses from the beet-sugar factories was given extensive tests as a substitute for soap, and when used at the rate of from 3 to 6 gallons in 100 gallons of mixture it served as an effective ad- hesive. The molasses, however. contains a considerable amount of / — = —'e PROGRESS REGARDING SUGAR-BEET WEBWORM. 65 alkali and other impurities which tend to make soluble some of the arsenic and copper in the Paris green. The soluble arsenic burns the beet foliage, and on account of this injury refuse molasses is not recommended. It may be interesting to add that in experiments which the writer made with Paris green against cther species of in- sects, using as an adhesive refuse molasses from cane mills, which was less highly charged with impurities, the results were satisfactory, and no burning of the sprayed foliage occurred. Several standard brands of arsenate of lead have been tested against the sugar-beet webworm in the Arkansas Valley, and with- Fie. 16.—Barrel sprayer in action against the sugar-beet webworm. (Original.) out exception the results have proven unsatisfactory. The arsenate was used at the rate of 6, 8, and 10 pounds in 100 gallons of water, and 100 gallons per acre applied, but the webworm was not con- trolled. In these experiments a large traction sprayer and an ordi- nary barrel sprayer were used. Zine arsenite, when used at the rate of 4 pounds in 100 gallons of water and applied at the rate of 125 gallons per acre, was effective. It was, however, noticeably slower in its killing effects than Paris green as recommended in formulas Nos. 1 and 2, and when used at this strength was equally 4s expensive as an effective application of Paris green. 66 PAPERS ON INSECTS AFFECTING VEGETABLES. Paris green will kill the sugar-beet webwerm when used at the rate ef 2 pounds in 100 gallons of water, but its action is comparatively slow. It can also be safely used on sugar beets at the rate of 4 pounds in 100 gallons of water, although this amount is excessive and unnecessarily expensive. All things considered, either formula No. 1 or formula No. 2 can be depended on for the most satisfactory results. Many beet growers deman‘ that an insecticide to be used against webworms shall be immediately effective. It is of course unreason- able to expect immediately fatal results from a stomach poison. When Paris green is properly applhed against this webworm at the rate of 3 pounds in 100 gallons of water, a fairly large number of © dead webworms will be found about the sprayed beets at the end of 24 hours, and at the end of three days practically all webworms should be dead. Dusting with Paris green and lime has also proven effective against this webworm when used at the rate of from 2 to 4 pounds of the poison in 100 pounds of air-slaked lime. The “dust” may be ap- plied by shaking it from a coarse sack or with a “powder gun.” This method is slow, would ticrease the cost of application more than 50 per cent, and is difficult to apply in an even coating. Occasionally a field of beets may have been irrigated just before an infestation of webworms becomes apparent, and in such a case the soil is likely to be so wet that the prompt use of a sprayer will prove impracticable and dusting may then be employed to advantage. SPRAYING MACHINERY. For spraying large areas cf sugar beets a geared traction sprayer of 125 gallons’ capacity (figs. 20-22) will prove profitable; but for the average grower, whose planting does not exceed 20 acres, this type of machine is too expensive and unnecessarily large, and a smaller, much cheaper sprayer, which can be assembled at home, will give satisfactory results. Such a sprayer may be fitted up by mount- ing a spray pump in a 50-gallon barrel on an ordinary one-horse. two-row beet cultivator, from which the “handles” and “shoes” have been removed. This arrangement will be readily understood by referring to the accompanying illustrations (figs. 15, 16). The four-row attachment is connected with the pump by a rubber hose and is fastened to sections of plank which are bolted to the culti- vator frame and extend out behind the wheels. The row attachment is made of {-inch and }-inch iron pipes and can be put together by a plumber. Three types of row attachments are illustrated. Number 1 (fig. 17) is the simplest and will give satisfaction under ordinary conditions. This may bé built to cover eight rows of beets instead of four. The eight-row attachment, however, is rather cumbersome PROGRESS REGARDING SUGAR-BEET WEBWORM. 67 and may cause some trouble by catching in fences, etc., when turn- _ ing at the end of the field. Number 2 (fig. 18) is so arranged that two nozzles are above each row of beets. This is desirable, but not } 20° Be Bo Fic. 17.—Four-row attachment for beet sprayer. (Original.) absolutely necessary, when large beets are to be sprayed. Number 3 (fig. 19) is so made that both the surface and the underside of the beet leaves are reached by the spray. By using this attachment *.. ee wee = oe Se Fic. 18.—Four-row attachment for beet sprayer. (Original.) beets can be very thoroughly sprayed and young webworms on the underside of the leaves will be more quickly killed than when only the surface of the foliage is wet by the spray. A nozzle arrange- ‘a y DETAIL OF NOZZLE . ._ i 73a ARRANGETIENT. SCALE /Z=/" rf » Fic. 19.—Four-row attachment for beet sprayer: Nozzles arranged so that both the upper and lower sides of the leaves may be wet by the spray. (Original.) ment such as is obtained with this type is necessary when Bordeaux mixture is applied for the leaf-spot disease (Cercospora beticola ~ Sace. Me 68 PAPERS ON INSECTS AFFECTING VEGETABLES. — — r ~~ I \ S ao? SEES ae ———s ee 20. (Author’s illustration.) 21.—Geared traction sprayer in action against the sugar-beet webworm. illustration. ) Geared traction sprayer suitable for use against the sugar-beet webworm. (Author's In fitting up a sprayer a strong, heavily built pump provided with an agitator should ove used, and the necessity of using first-class PROGRESS REGARDING SUGAR-BEET WEBWORM. ae nozzles is imperative. The nozzles should be of the Vermorel type tf LL TT EL TR Fie. 22.—Filling a traction sprayer for spraying against the sugar-beet webworm. (Original. ) ' (fig. 23), which delivers a fine, mistlike spray. This type of nozzle, together with the pump, hose, and other fittings, can be purchased from any reliable: dealer, and the entire sprayer can be fitted up at an expense not ex- ceeding $25. With this sprayer and a horse it is easily possible for one man to spray 95 acres of sugar beets aday. Withalarge traction sprayer a much greater acre- age may be treated in the same length f ti Fic. 25.—Type of Vermorel nozzles suitable for spraying Oo ime. sugar beets against the sugar-beet webworm. COST OF SPRAYING. The cost of labor, materials, etc., for spraying sugar beets will vary under ordinary circumstances from $1 to $2 an acre. The price received for sugar beets by the growers in the Arkansas Valley 70 PAPERS ON INSECTS AFFECTING VEGETABLES. usually exceeds $5 a ton. As previously mentioned, a.defoliation by the sugar-beet webworm may reduce the yield of sugar beets 1 to 5 tons to the acre and also cause a loss in sugar content and purity. As this damage can be absolutely prevented at a cost not exceeding $2 an acre, the profits from spraying infested beets are apparent. CONCLUSION. An easily accessible supply of water will aid materially in keeping down the cost of spraying. Water from the irrigation laterals may be used, but in all cases it should be carefully strained to pre- vent dir,and other material from getting into the pump and clogging the nozzles. Water that is highly charged with alkali should be avoided. : After a sprayer is used it should be carefully washed with clean water and all the working parts thoroughly oiled. It is a mistake to allow a sprayer to stand in the field exposed to sun and weather, and it will pay to keep it housed when not in actual use. As a final word, it may be well to state that webworms, and with few exceptions most other insects which affect sugar beets in the Arkansas Valley, can be easily and cheaply controlled. When this fact is more generally accepted by the beet growers it is safe to say that sugar beets will produce still better profits. DDITIONAL COPIES of this publication may be procured from the SUPERINTEND- ENT OF DOCUMENTS, Government Printing Office, Washington, D. C., at 5 cents per copy eee DIV. INSECTS, Pe ae ag ae Ss eS, 2 %3 i UV. S. DEPARTMENT OF AGRICULTURE, |: BUREAU OF ENTOMOLOGY—BULLETIN No. 109, Part VII. L. O. HOWARD, Entomologist and Chief of Bureau. PAPERS ON INSECTS AFFECTING VEGETABLES. THE HORSE-RADISH WEBWORM. BY . | H. O. MARSH, d Hniomological Assistant. issurD January 30, 1913. WASHINGTON: GOVERNMENT PRINTING OFFIOE. 1913. BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Martarr, Entomologist and Acting Chief in Absence of Chief. R.S. Curtron, Erecutive Assistant. W. F. Taster, Chief Clerk. . CHITTENDEN, in charge of truck crop and stored product insect investigations. . Horxins, in charge of forest insect investigations. gpa HuNTER, in charge of southern field crop insect investigations. WEBSTER, in charge of cereal and forage insect investigations. QUAINTANCE, in charge of deciduous fruit insect investigations. Pures, in charge of bee culture. 1. Rogers, in charge of preventing spread of moths, field work. Rota P. Currie, in charge of editorial work. MABEL COLCORD, in charge of library. H D D M L. F. N Oi > Truck Crop AND SToRED PrRopuct INSEcT INVESTIGATIONS. F. H. CurrrENDEN, in charge. ©. H. Porpenoe, Wm. B. Parxer, H. O. Marsu, M. M. Hieu, Jonn E. Grar, Frep A. Jonnston, C. F. Srant, D. E. Fing, A. B. Duckert, entomological assistants. I. J. Conprr, collaborator in California. W. N. Orp, collaborator in Oregon. Tuos. H. JoneEs, collaborator in Porto Rico. Marion T. Van Horn, PAavuine M. Jonnson, Anita M. BALLINGER, preparators. II a it. a CONN TS Page ING IE sc ot RR ED 4k Eg wine 2 ue ol ee 71 SNM HORE EIGER os cs ee ey Gd dele eee dads Se a es 2 aR Tl Pemeeene trance 2nd habits. ..........22.--+.-+.-<- <2 ¢o- et ee eon eee ee BEL Se SRS EE SR 29 8 Sg Sb 73 NIE ene ess. Pe ee a i Ge Se kOe Sa ie coast ms odie 73 ieelavine record. /...2..-.-2.2.-.- Sehccieunbid st Me Saget AL Bie edhe ARS ges 3. ry 75 Coos EL EIEL Tach RS ae 2 SE Se es 75 Experiments with insecticides.........-.....---------- PG a KP cs Sie 76 emrmunrnnr fast IA STONE COT GEOL cS a IE alk baie! gape ley civ == let Seige = 76 ROMANE rte tenho ee le oc a ano Vo aaa ah 76 LLL US PAT PONS, 3 ; Page. Fic. 25. The horse-radish webworm (Plutella armoracia): Adult or moth, side waew and With waned spreads... 22. 52 SPs ce cceanc ee 72 26. The horse-radish webworm: Larva, lateral and dorsal views... -...-..- 72 Poehe orse-tadish webworm: Pupa....\..2..-..2.--lisesseeie- ene e ee is eee fe orse-radish webworm: Cocoon... 0-22 te eee ee i III SO a A A AT ee ee ee oe ‘a at) ae) OP NES $2) i ts y’ To had } F a ae! @ AA ; < ~ ‘ ‘ - “re * F , * "Cotes KAA OD i 7 » Z , J WD. Fe ater ee etait My iD! See wea ¢ ‘ : i \ iste s, me gt Atty) + fat A tampa ; Sy 40 Per ers ee ae ee ee «phe “—" Tig * rire - ine eee ae weer t ne Gy le. site han ; went mae? = ey op God. sire a BED RS. - pre Fe Oy FE TA EPPS A Saree me a + eae miele ay ¥. Os ee a! ¥ a ee tae ee was potion ¥ Wye? DAF 2HOLTES Tees Tt at, APs icin w slaehk -: DEANE) athsut)) roe tow duh | iid A gh eg Se Nga: a) big fe oa ip pasigs aut die Ce en tatots ies 1 urease. pene cnwdaw debe {ie on = aq Ui i 3 t me u 3 rh “ , { "4 * Tats dc ig le po era “0 eer... ee ae ae ee _ 3 2 eee “ ot ~ om ; : SO es eee ‘ U.S. D. A., B. E. Bul. 109, Part VII. T.C.&S8. P. 1.1, January 30, 1913. PAPERS ON INSECTS AFFECTING VEGETABLES. THE HORSE-RADISH WEBWORM. (Pluteila armoracia Busck.) By H. O. Marsa, Entomological Assistant. | INTRODUCTION. At Rocky Ford, in the Arkansas Valley of Colorado, ho-se-radish is grown on a very limited scale for home use. Among tae insect enemies of this vegetable are a flea-beetle, Phyllotreta pustlls Horn, the spinach aphis (Myzus persice Sulz.), the common cabbage worm (Ponta rape L.), the southern cabbage worm (Pontia pritodice Boisd.), the diamond-back moth (Plutella maculipennis Curtis). and the horse-radish webworm (Plutella armoracia Busck). This htter species is a new and hitherto unrecorded truck-crop pest. As notaing has been published regarding its life economy the author has dr:wn up this preliminary article touching its occurrence, life history, habits, and remedies. @ OCCURRENCE IN COLORADO. This species was first found at Rocky Ford by the author during the latter half of April, 1911. At this time larve, pupe, and adults occurred in moderate numbers on horse-radish in one garden. The species was observed in this garden at various dates throughout the spring and summer. The larve checked the early growth of the plants somewhat, but no serious damage resulted. In 1912 the overwintered larve became active on these plants, which were then just showing above ground during the last days of March. So far as the author has been able to determine, the infestation is limited to about 15 ‘‘clumps”’ of horse-radish plants in one garden at Rocky Ford. Careful search was made for this species on horse- radish in other gardens at Rocky Ford and on various species of wild and cultivated cruciferous plants in other portions of the Arkansas Valley, but without success. The infested horse-radish plants 71314°—13 71 i2 PAPERS ON INSECTS AFFECTING VEGETABLES. have been in their present location for several years and it is impos- sible to determine their origin or whether they were infested when planted in the garden mentioned. GENERAL APPEARANCE AND HABITS. The horse-radish webworm (fig. 25) is a beautiful, slender moth belonging to the lepidopterous family Yponomeutidz. The wings are cream colored with a brownish tinge and have an expanse of about five- eighths of an inch. The moths are shy and hide among the foliage of infested horse-radish plants. When disturbed they fly readily for ashort distance and wually promptly hide. In eomttyaty they feed eagerly on } diluted honey. | Seed The eggs (fig. 26, c) SA are scale like and are Be Re usually deposited singly on the upper or $e WS, lower sides of the P—- NO SAS leaves. Fic. 26.—The horse-radish web- © FiG. 25.—The horse-radish webworm (Plutella armoracia): Moth, worm: a, Larva, lateral view; side view, above; moth with wings spread below. Enlarged. b, larva, dorsal view; c, egg. (Original. ) All enlarged. (Original.) The newly hatched larve are pale yellow. The mature larve (fig. 26, a, b) are yellowish green, with a more or less distinct yellow or orange band across the dorsal surface near the middle. Almost immediately after hatching the larve spin compact webs under which they rest and feed until mature. The webs are white or gray and are remarkably close-meshed. When the horse-radish plants are young the larve web together and feed on the first spikelike leaves and later a favorite location is among the blossom buds. With older plants the larve feed on the leaves generally, usually selecting the most tender ones. THE HORSE-RADISH WEBWORM. (3 Their most noticeable injury is caused by checking the first growth of the plants early in the spring and destroying the blossom buds. The pupe (fig. 27) are pale yellow marked with brown and are inclosed in cocoons. The cocoons (fig. 28) are placed on leaf petioles or among dead leaves and are exquisitely beautiful, silver-gray, lace- like, cigar-shaped objects. LIFE HISTORY. There are four generations each year and activity is continuous from the last days of March until well into October. . eo. eee ee! ee coe Moths mated. State LO. 8s Fh ee eee et ee ee ee ee ee First eggs deposited. Sie 2OPAL. is at Ty Tae ALCS SEL SE. OTe. i Eggs hatched. daly, Be eh giee ae ee eee de Peele First cocoons formed. duly 6.4.2 Pe PRROE P OL NVrny AN (ugeoliniing C SPANOS First larve pupated. BLY BG oes os Ds erage gene ge ee First adults issued. From the above record the stages are as follows: Days Wap state 2 tee FS eed 11) NAS CAR, SU. OS or 10 Tarvallietage.: 0G. De ee Je ka BU A. 16 Puyal stage . Yet.” 25. eee gw se oS. ee 10 Wotals. 2. bo ee eee I oe a oa Sw 36 A pair of these moths mated July 24 and were placed in a separate cage. Third generation. Felis oS oe te CR BE or ee 2s 2 Moths mated. July 26S Bae eae ok = s First eggs deposited. July 31... 1): coer eee eet aes a ee Eggs hatched. 1, pe AE iy MT aS ER SY OR FAP RA BEB aT age First cocoons formed. i Ter a ae a a oe ee ee 2 Gi First larve pupated. Piste! YS bidet ina San REN See GES pee am ok wes First adults issued. From the above record the stages are as follows: Days. TGP SCALE cs Ge sg TO oa eee ee cals oe he whe oe Sele en 5 Larval stage... =). VIS RAS 2." eee 13 Papal stage... . = 29 goa pins ere >4p's oe a-ae Os 8 gS! PR © Seen PAD Seat Pee SUN 26 A pair of these moths mated August 24 and were placed in a sepa- rate cage. Fourth generation. B25, ROE RECO Rat er eA SANNA RN PIE Moths mated. PO Oe on ae vag pat ESE ere a a al a First eggs deposited. oy 1 Mia Mil bes SND a ch 8 5s fre” CS Se IE ON Eggs hatched. Pept AG. 92 AES LA ee a eon ee First cocoons formed. Sepes 8s bij Lobe eee aie Le eee Ot First larvee pupated. Oet. TL. oan d. Seach aes eee 4 eee First adults issued. From the above record the stages are as follows: ays Pipes Shape). wick We oe Ba ww ote eee eee eee 7 Latwal stade...2.226-.-) 2: Oe Meee Saree pe ol aetna o aee 27 Bupol diagescwss 292) 20s Soe. Lo eee ee ee ee 13 THE HORSE-RADISH WEBWORM. 75 Only a few adults of the fourth generation issued during October, and these deposited no eggs. The majority of the larve of this _ generation went into hibernation about the middle of October. These larve will hibernate among dead leaves and in cracks in the - soil and develop moths during April of the following spring. It will ' thus be seen that the larval stage of the fourth generation may vary _ from 27 days to 6 months. EGG-LAYING RECORD. On May 3 a female issued and mated with a male which had emerged a day earlier. The pair, while still in copulation, was isolated in a _ eage containing a wad of absorbent cotton saturated with diluted honey and a horse-radish leaf. Eggs were deposited as follows: No. of eggs deposited. No. of eggs deposited. a) SYS ea ee 29 | Win, (Satie 20 os Nee 36 SE a StF ETN ERG) AS ee aeereceutiegny 125 16 ee ee 12 A C4 Se ER PL ORERNE tr ep 331 | The moths were observed copulating May 3, 8, 13, and 20. The - male died May 28 and the female June 4. The length of life of the male was 26 days and of the female 32 days. _ The rearing records were obtained in the laboratory at Rocky Ford, Colo. The cages were placed in a window which was kept open night and day. Food was supplied the moths by putting in _ wads of absorbent cotton which were saturated with honey and water. _ This food was eaten eagerly. In the cages the moths were quiet and _ easily controlled. In all cases the larve were fed with horse-radish _ leaves. ) NATURAL ENEMIES. _ Only one natural enemy has been found preying on this species at Rocky Ford. This is a small, wasp-like hymenopterous insect _ which Mr. H. L. Viereck has described as Angitia plutelle n. sp. This parasite is evidently largely responsible for checking the increase of the Plutella larve. The adults were found in the field from the latter part of April until the middle of November. In the cages the first adults developed from overwintered Plutella larve on April 23 _ and 27. It is probable that the parasites live through the winter as _ eggs or larvee within the bodies of the hibernating Plutella larve. 76 PAPERS ON INSECTS AFFECTING VEGETABLES. EXPERIMENTS WITH INSECTICIDES. During the spring of 1912 the following experiments were conducted at Rocky Ford, Colo. On April 8 several infested horse-radish plants were sprayed with the following mixture: PANS SYCPD. oc. 5 < pe wae se cee ees ee Sabshen eae iede cece Pi aia Whale-oil soap... . 2 2Erot ce nes Saseet oe eee See do.. 8 Water. ....2.2.- 22. 2. gaiecameeg eet ohn ek core ae eee ee eallenee 100 These plants were kept under close observation for several days, but no dead larvee were found. On April 29 several infested horse-radish plants were sprayed with the following mixture: Arsenate of lead oem ei eg ie ee SU cueletree i a cn ee pounds.. 10 Whale-ols0ape 65. ton sent ede eae ware emiee es e e do... ae Watetd 222500002 SS RS RE ee gallons.. 100 This experiment was likewise a failure and no larve were killed. In these experiments the poisons were carefully and thoroughly applied. The surface and underside of the leaves, and in fact all portions of the plants above ground, were coated. This treatment, however, failed to kill the 'arve. This was due to the habit the larve have of resting and feeding under compact webs, where they are completely protected from stomach poisons. RECOMMENDATIONS FOR CONTROL. The experiments indicate that this insect can not be controlled with arsenicals. If artificial control measures should become neces- sary, much could doubtless be accomplished by burning the dead horse-radish leaves and petioles during the winter. After the dead leaves are removed the surface of the soil about the roots of the plants should be thoroughly stirred with a rake. This cultivation would crush or bury the hibernating larvee which were resting in cracks in the soil. CONCLUSION. The investigation of this insect indicates that infestation is limited to a few horse-radish plants in one garden at Rocky Ford, Colo. In this garden the larve have evidently been prevented from causing much damage by a hymenopterous parasite, and at present no arti- ficial control measures are necessary. AP DERN AL COPIES of this publication may be procured from the SUPERINTEND- ENT OF DOCUMENTS, Government Printing Office, Washington, D. C., at 5 cents per copy INDE aee Page. _ Agromyza diminuta damaging cabbage in Hawaii. ...........-.--+--------¢-- 33 Agromyzid reared with Pachyzancla bipunctalis from beets and Amaranthus. - 22 Wgrots crinigera damaging cabbage in Hawail.............-5 220+ ----<----5% ae | Amaranthus— : Emeivatred, food plant of Hymenta fascialts......02-. so 4dan Jade ope dee 2. MERRIE OL BETO YZ 10: 25,2 a= euae'= SL 2 o's wear nid Anam erd de alge a eee 22 _ Amaranthus mangostanus— bibliographic reference..........- a Rech er Py yg ba fe ye 15 PMA OL EY IMCNIE JASCIONIS eo ok oon a 2 ote ive, cla db At ard «iim woe, Sue ares RO 14, 15 _ Amaranthus retroflexus, food plant of Pachyzancla bipunctalis............- Lees: 18 naroninus sp., 100d plant of Hymenia fascialis......4-----------------02e5-6 1 _ Amaranthus spp., food plants of Hymenia fascialis.................--2----+--- 2 _ Amaranthus spinosus, food plant of Pachyzancla bipunctalis.................-. 18 _ Amaranth, spiny. (See Amaranthus spinosus.) Sesimbrosia, food plant of Pachyzancla bipunctalis........-~.----++---0----++---=- 21 _ Amorphota sp., near orgyix, parasite of Pachyzancla bipunctalis............-..-- 21 ; mug plies, parasite of Pluiella armoracea..... 12.0. 25-4. seid = ~~ 224 a--m= 75 Apaniteles n. sp., near agrotidis, parasite of Porosagrotis vetusta..........------- 51 _ Aphides, control by nicotine sulphate and whale-oil soap. .............-..--- 10 _ Aphis brassice damaging cabbage in Hawaii.....................-.--22+2---- 33 Arsenate of lead— against Colorado potato beetle..........---:-2-------- Fe cis Aye ee eee 53, 55 BeamneuLWworm, Forosdgrotis Velusid. ... icbet a3: 2. dk. 1h. Sock eee ee 49 and lime-sulphur against Colorado potato beetle........-....-----+-------- 53, 55 and molasses against Hawaiian beet webworm............-----+-----++-+-- 8, 10 umememraeses acainet melon fy. oo. je. a2 cee eee Ch Sn “15 les bee gee 8-9, 10 and whale-oil soap against horse-radish webworm........-..-.----------- 76 and whale-oil soap against imported cabbage webworm.........---------- 40 unsatisfactory against sugar-beet webworm...........-..---------------- 65 _ Arsenical and Bordeaux mixture against imported cabbage webworm...-.-.-- 43 _ Arsenite of zinc— Pome elorado potato beetle... |. 2 os nen es th eee eesaee\-5 - aasita- Be 53, 56 a meerneaT-DeCt WD WOFE « oo oa. F. - aij im Sopiciny-inys Aen Sante = eek eR Ses 65 and Bordeaux mixture against Colorado potato Seti LSA PM. RSE P12 53-54 4 Autographa brassice, association with Hellula undalis in damage to truck es ahs ao hain dw die se eS aces oe hho He hE wteebene 26 _ Autographa precationis— ' _ control by nicotine sulphate and whale-oil soap. .....--...+..--+------+--- 10 CMMRME CCA ARO A STA WEL ge a an mings te dass cert Sima ee < OR 33 _ Beans, food plants of Porosagrotis vetusta...... ere pe Satie A NRE oe ee 47 _ Beet army worm. (See Caradrina exigua.) Beets— . . Senet a AETOMTAIC : oo. ns oo a ble lad ae Be aug ead bi ed we 22 food plants of Hellula undalis. ..... Ss voor a ee ack cal Peel a Ste era aod alanits Of Aymenia fastidlis.. 2. 1. << = aicncre« =a oacrmendt tes eek > 4ueties 21-22 50498—16——2 - Sve st Tele ee Pipes 78 PAPERS ON INSECTS AFFECTING VEGETABLES, Beets—Continued. , Page. food plants of Pegomya ruficeps.....-.---.-.-.---+----- oti a 22 stock, food plants of Hymenia fascualis......- 22.5.4 2.252 22-2 -< + ee 2 sugar; iood plants of Hellula undalis.. 122.222.2454, he ates he a eee 24 sugar, food plants of Hymenia fascialis................----------- cere 2 sugar, food plants of Loxostege sticticalis........ wl etcgkeest - eae ea 57-70 table, food plants of Hymenia fasciahes<222e-20... 22... eee 2 Beet webworm— Hawaiian. (See Hymenia fascialis.) southern. (See Pachyzancla bipunctalis. ) Blackbirds, enemies of Loxosiege sficticalis.- .. 022. PL Se 62 Bordeaux mixture— against imported cabbage webworm . 2.7222. 222.2. 1.2 eee eee Preteen’ against leaf-spot disease of beet. ::....2.i22 2.0220. 2 ee 67 and arsenical against imported cabbage webworm...... one 3 ee ‘ante 43 and arsenite of zinc against Colorado potato beetle.....................--- 53-54 and Paris green against Colorado potato beetle..............-..-----.----- 53-54 Botts repiiiahs—Pachyzancla bipunctalis. 02... =< Sa eo eee 21 Botis rogatalis— bibliographic reference--- 2.227.222.0772 Boe 44 ——Hellula undalis: 2000002 o oo eT ee oe ek 28 Bracon sp., parasite of Pachyzancla bipunctalis..........-.-..---/--2.-+------- 21 Burning against imported cabbage webworm............--------------------- ~ "43 Bursa (Capsella) bursa-pastoris, food plant of Hellula undalis..............---- 31 Cabbage aphis. (See Aphis brassicx.) Cabbage bug, harlequin. (See Murgantia histrionica.) Cabbage— i , food, pliant of ‘Hethrla natiahs. 125-0 Soe eee ce 23, 24, 25, 26, 27, 30, 32, 34 food plant of Porosagrotis vetusia.........-..9..4.. 4) .. 222 ee AT looper. (See Autographa brassicx.) webworm, imported. (See Hellula undalis.) worm, common. (See Pontia rap2.) worm, southern. (See Pontia protodice.) Cantaloupe, food plant of Porosagrotis vetusta.......-.. ote eas = ea oe 48 Caradrina exigua— damaging cabbage in Hawai... $220.00 2 oo Oe 33 nicotine sulphate and whale-oil soap as remedy.......---...----.-------- 10 Cauliflower— ; food plant of Hellula undalis....-..... 02 0-.-=-+--=-2-=- +i 30 food plant of Pachyzancla bipunctalis: }- 0.2.2.2 2222 ee 3 21 Cercospora beticola, Bordeaux mixture as remedy...............-------------- 67 Chelonus blackburni, parasite of Hymenia fascialis.........--..--------------- 7 Chenopodium album, food plant of Loxostege sticticalis..........-.-.-.--+++--- 59 CHITTENDEN, F, H.— and MarsH, H. O., paper, ‘‘The Imported Cabbage Webworm (Hellula undalis Fab. YP or ewe elaine he bone shee ee ae Oe te ran a ae 23-45 appendix, description and synonomy, distribution, history and bibliog- raphy [of Hymeni fasciitis)... sooo si. - ~~ = «eee oo 12-15 paper, ‘‘A Little-known Cutworm (Porosagrotis vetusta Walk.)”’....-.-.-.- 47-51 paper, ‘‘The Southern Beet Webworm aaa aan ee Fab,)’’.. 17-22 Collards, food plants of Hellula undalis...............------------ . 23, 24, 26, 30 Uorn, food plant of Porosagrotis vetusia.. (J... 0- cee oe ee = nn ae eee 48 Cotton, food plant of Porosagrotis vetust#i... 2.232220. e ce on teas seee ae ee 48 Cowpea, food plant of Porosagrotis vetusta.............------ =k oe ee 47 Cremastus hymenix— Page. Perse TOnECITCLeTenCe: |. 22 5. Shh.c £) pba coe ee aE oe ark e's we 15 9 Ree eC Rs ERICH IG fUSOWELIS: JS (She oo eee hc ce MINE intstetate Wheeler (02% 7 ~ Gucumbers, occasional food plants of Hymenia fascialis.............2.2--+---- 2 _ Cultural methods against imported cabbage webworm.....--..-------------- 42 Culture, clean, against’ imported cabbage webworm...-..........----- Gy 42,43 ‘*Cutler’s grass,’’ colloquial name for Portulaca oleracea.......----.-+--+--+-+-+-- 31 Cutworm— ; 7" granulated. (See Feltia annexa.) 3 “spotted-legged,’’ name applied to Porosagrotis vetusta........-..------- 51 - Dacus cucurbit72— ; # control by arsenate of lead and molasses. ..-......-..--.-50.20-6832 00222 8 eee eanbace mn Hawa. 25062 sje ines we ones 2 33 | _ Dandelions, cultivated, food plant of Porosagrotis vetusta.....--------- atrags 48 | = Dewberry, food plant of Porosagrotis vetusia....-.........----------++-+- ei AT. _ Didamond-back moth. (See Plutella maculipennis.) Diosphyrus vulgaris, parasite of Loxostege sticticalis.....---.-----------+------ 62 Disease affecting Hellula undalis in Hawaii. .(See ‘‘Wilt.’’) | “Dragging the log” against southern beet webworm. .....-.-.---.-.---+------ 22 | _ Dyar, H. G., appendix, ‘Description of the Earlier Stages” [of Hymenia fas- | : at FEE ON St cain SRE Cina hk Ce ties & fT EROS 11-12 | _ Evergestis rimosalis, bibliographic reference. ........-..---.--- RaW Sree os 45 eras, food plant of Bymenia fascialis..5. 22. 023006. 8s ee dees ee ret Pemasen pusie, patasite of. Hellula undals...-..........2.-26200~ eee woes 31 Fall plowing against imported cabbage webworm.............--------------- 43 Feltia annexa, association with Porosagrotis vetusta in injuries.....-..--.------ 48 Hand picking of no value against imported cabbage webworm........-.--.---- 33 Hellula undalis— CN a eri, LIK Giiei. S ass eee oe te Vee td Ptah) TO eee 44-45 conclusion as to remedies.........-...--.-- ble tye Bepelek wae ioe ee ee 41-42 mmeoeaoate im Hawaii... c0k ue eee Le pe eee LOL 33 Beemiian avi life-history notes. ..<< 22.1 ih... “cect lene rie Sen et-29 Seem IRMEN LORI, HePN Sabie, Aliana Re ee Stele eras be aera sk SPSL T Oe 30 See PARC IONT.Ws. oo hc URI Re ee oe eo 28 Peeeereth records we eo. we as Jee RL a ol. LPP. AE LY 37 MES Sera tice i Moet, oes RR OR ot ak Seen os SR ee 31-32 PPeeRMTPEMM ETON ATS Se ese yes ok Se ESS Sule oe tie tien elec cs PO we 37-38 | experiment in screening a seed bed as remedy.....-.-.------------------ 41 experiments with insecticides in Hawaii... .! 2/0. 2. . 229 oe ee ee 38-40 a SLLELE CIC TAR SERIES "aha eae Rs Cg A PR Le 35-36 fae plants... 22.2.2. Ree Re EN AES Dhl CU ae SOE oe 30-31 MEME MOTT Sao Ge an! Oe lei ik SEs od bas Cee aoe 2 POE 36-37 introduction, spread, and ravages.........-- Phased 2 ke AO Pee 23-27 See orown Vdescripiion. =) 20.920... ..2s6.2 lo 26 5... SUE eKzO Peenewly natiched,' deseription 2.200220. 60. Loe eae 29 Peccunscory and: habits in: Hawali. o.oo. ee eee PLR 34-37 IE CHOON OO cx chee Ses Pea I) Se a) oe SE 27-28 MEME, oe rte Gore oe Tee Gu. ee ee ee “28 Pe Cara ULOMN. ose ener ae ck clos ets ot TS PO EN aS 29-30 Penna t1Ols 1OD COntOL. 2. L cs. ele ore ett Se OE 42-43 Beaman CeNErAbIOnee sco. SEOUL JIS. TARE LEP eE i BPRS 36 Panny ahy COE. eI I) ee, PERG SP ee NR. A GS CPO 28 PEPE AMES ear ee. N27 eka e2 Sos oh ae sees ee ee eee kes 36 A ee DE et os tey ae hams ee eee 80 PAPERS ON INSECTS AFFECTING VEGETABLES. Horse-radish— food plant of Hellula undalis.......-.- chew especece ae $2120 eee insect enemies in Colorado. .:.2-220. <2... yes BA BS 2 SBM 71-76 Hydrocampa albifascialis= Hymenia fascialis........£...2-.-22--2 2222220222225 13 fiymenia, description of genus... 2.2. LAMA. Le. Se 13 Hymenta diffascialis— Hymenia fascvalis 2.2. 222 23202 Ss Sa 13 Aymenia fascialis— , adult, description... ...--..--2 J2. i cows See 4 13-14 mrblideraph yo" 02S Ie eee ee o---- - CUNEO) 228 2 15 cocoon, description. .. fo. 232c0 SES. Pov i@us be _ - 12 description of earlier stages. _..:...2.-2--0-222222-2.)-15 111 ee 11-12 disiribution._-*.. .-- 2... -<_..:__Saeiens Re Ae ee 14 epp, description... 22g he cnet cise 1 opel! 2b ae il erlemiies: 22 2 oo... esti eden cee og) a 7 foo planis:. 2-2... 222-2 82. 22 ee Sees”. Se 2, 14,15 habris-- 2-2 oo 2250. SO. 2S 2 ee es AE ee 3-7 history 3. 22. 22.22 5 222 LR SS Se ee 14 aviary. 220-22 2 Se a Oe 5 Se Ge ee 2 insecticide experiments......00 0 SLT ec. Joe ek - 7-11 larva, descripisom: ois u.00 wl bs 2 di Len os etree | See 1i-12 Bie Srtary ss oe Se eh ste eee ee ee eee 8 3-7 pupa, description. - /...-5 +... L225 eet sige dd vu aa 12 reared with Pachyzancla bipunctalis from beets in Florida...........-.-...- 21-22 BynenyMmy..- se ee ee Le ae Se 12,13 Hymenia recurvalis— brbhographic reference... 22.-.- = 3252 ...%0.5-01be. Sop eSeee 15 = Aymenia fascias: so o8 sb cc saeco ax ths eget Se e.d 2 see 13 JOHNSTON, FreD A., paper, ‘“‘Arsenite of Zinc and Lead Chromate as Remedies Against the Colorado Potato Beetle”...........-......--.------- 53-56 Kale, food plant oi— \ Petina annera.- 2.2 2+. 262-2 - eel eed =cne- a debe) 48 Hetlala undalis . . 22: - -- = - 2+ 2-42 = -- > - pee ee ee 24-30 Porogugrotiatetusta << 2.- - 2 2352200 2; - Bcc ort vee 48 Kerosene and soap against imported cabbage webworm.......-..---.-..----- 42 Kohl-rabi, food plant of Hellula undalts..-....-.-..------------42-2e5-ne eee 30-32 Lambs’-quarters. (See Chenopodium album.) Lead chromate— against Colorado potato beetle. :-. 25. «. i<.)-.66-. athe 53-55 against Hawaiian beet webworm.. . .-.. 2.2. #2: se. 42bss segs ce ee 9,10 Leaf-spot disease of beet. (See Cercospora beticola.) Lettuce, food plant of— Pele GHNETE Ee oss 2s Oot ee SUL sae. d » a 48 Porosagrotis vetusta::.-.-:.-.....---- 05-06 sockee 2s Jose - Je 49 Leucinodes exemptalis— bibliographic reference... .....-.-.~..'.--+ j=- bees =k Ut eee at = Hiellula undalis. ...-.- 222-2. --+250-552-beiseb-i abl Sed: bee 28 Lights for trapping moths of imported cabbage webworm...........--------- Sng, 43 Se Lime and Paris green against— Hawaiian beet webworm.....5.2 5. - 2.2.5) .0-2 4 Je 220.2 eee sugar-beet webworm..-...-:-.-.--....2.5--.. 2. 2s shee oe Lime and Paris green, dry, against sugar-beet webworm..............------.-- Lime, Paris green, and whale-oil soap against imported cabbage webworm. INDEX. 81 Lime-su!phur— Page. mem Glawavian beet wepworm. 22.22. 5 ueegeccen a leech oe es 9,10 and arsenate of lead against Colorado potato beetle...... eee PRE 53-55 Limnerium hawatiense, parasite of Hymenia fascialis......-....--------------- 7 Limnerium tibiator—- Peete Gh AU ogra pla UrassiomEs AS SOC EUR RE PS fae) eae 31 Permaine war incols indiguiel ims «stl ELS Se ea see 31 eeeetetne Gl CUCL: ChUCLTCFOTUMtn 2 Peo LEP US ee ae eee a 31 Beapable parasite of Helluta umdaliss 22 l250.02 Sere CL ee ee are minennG picid, parasite ol Porosagrotis vetusta.... 22.2520 eee eee ee 51 Loxostege obliteralis, resemblance of larva to that of Pachyzancla bipunctalis... . 20 Loxostege similalis— MRE ONOUCHULCPOC 252) 2 TR OS PL OLE TSS ST SLE Peat Pee eee eee 21 resemblance of larva to that of Pachyzancla bipunctulis....... ye Seve ae ee ee _~ Loxostege sticticalis— OO ele LDCLEL E51 a a a gS a a Maegan We 58 Pe MCEA OMT CE rine re LEE NU eee See ek loge kos 2222 ld he eee 58 See Au ON ere nie Shs Mer ue kiya at yd eS Sede thal 63 ennelmeions feeardine contro! experiments--/.. 222. 2..-2..22.2.-20- 222222 70 | control with barrel and geared sprayers. --. - re Medea aa crs) pee lB 2 ST LLBEL 2 cto eh.eaSuiccptedinan eam seid Cutt dnd SR a eerie ioe nor NL nk ee ee 62 ese I 2) tae Meet hoe Cree See's OU Sry f Sek Maa ahs see. Po Ameaee 59-61 TSAR 2 eit eae a gin aa atic i ate ae a i i re NS 61-62 eeenrreay ren ays LN at 222 BUR SEWED PN ea Fae Bee eee eevee oon hea 59-61 perseomnrourin damage to beets: 42.1.2 2222200002. 7 eee epee ts. Vier ee eae te gs pane Gee ee oe Me ie eee 63-66 | RMP ONCOL a she. Se eee ee See Spgs ears ean ere mort Aoi fs 69-70 “spraying machinery........... sige Nae Oh RAN WAS dey? hl clap eget. ES AN,” 66-69 _ Mangel-wurzel. (See Beets, stock.) ® Marse, 1. O.— 7 F, H. Chittenden and, paper, ‘‘The Imported Cabbage Webworm (Hellula | Coa iy SIS gaa AA Aiea alia acme Siac Os hell aoe kana hm i 23-45 | paper, “‘A Report of Progress Regarding the Sugar-beet Webworm (Lozos- 5 EESRTORICHL ES TIME) Fee meres ck UE WTS PN a. Ad IM 2 Sere eee een 57-70 : paper, ‘‘The Hawaiian Beet Webworm (Hymenia fascialis Cram.)’”’........- 1-15 paper, “The Horse-radish Webworm (Plutella armoracia Busck)”’......-.-- 71-76 Melon fly. (See Dacus cucurbite.) weicoris oulguris, parasite of Hellula wndalis...:...00 2222202 31-32 Molasses— and arsenate of lead against Hawaiian beet webworm.................... 8, 10 Seerormenate or lead against melon fly-.2..222.02. 22-22 ae 8-9, 10 refuse, substitute for soap in sprays against sugar-beet webworm.......... 64-65 PET ers rome, ‘distribubion.. 20258. kyle resi fire 23 feed, iood plant of Hellula wndalis::....... 2.20.02. 2002 ee 24, 27, 30 PeEmeneenrcr Or Norse-radielt So 2 V2 eA SN ee rel Nicotine sulphate and whale-oil soap against— 27a Ee sgh TREE 9 | Aree PAS ROM A AR ah Sei Rn Maeda ahi, ul " 10 Sis pon aed iia IER ae Meet bade ial gs Cane ean MEME We 10 PEON EA ASG WOT uy ENO OS ee ee SST oe Be ae 10 Peet eele mitre Ste MMO RTL) PaO Lh, EG 10 Pawetian eat webwornis wil. soe ey se site ea pete ie 10 Pampa Wleyniipnn preculion ise 2. VoD L822 e ee EE Os 10 enon ecu mmedivoriy O00. UP hel ht Aenea Se eR ee Se nano Pe eee tee ye tes eC hres, elon aM Rin} Pia i dee Berens « BOTS 10 82 PAPERS ON INSECTS AFFECTING VEGETABLES. Nicotine sulphate, Paris green, and whale-oil ‘soap against imported cabbage INE ao Sn as ain kn win be ee ae oes 22a Pachyzancla bipunctalis— apetated IMSeCIS~... 2. oP ania ae es nee Bow oe ce eee oe ae MesrripiVvVe. :. 2.0.0... 2s eee ob bene Jo eA < 6 dnc eee ee distribution. . -.- 2.0. Sse ee tise ~ ee ~ oe i Gee Gescription.. . .s2-5- ose. - see soe sh ee GMGMICB oo oan we enn ee wie ei so ol ie ee historical and biological notes. - - - 202. -- eo ncn eee i eee eee injurious occurrences and notes on habits...................--..-------- larva, description. ..< 2.255. 0: = oo. desea caw den ase nsee oo ene moth: description. 2.223.022 62 e222 feo a pupa, deseripuon. oo. 6 a ees sae mth de iene = 4a oie ae = RONICGIES fo Mes cae en ign oo ee tea kin oad ee SS! resemblance of larva to that of Loxostege obliteralis................-+------ resemblance of larva to that of Loxostege similalis........-.....---------- Paris green— acaing£ sipzarbeet webWorm.......-.. 22. =. -a-5<>-+s.e-454<. nee and Bordeaux mixture against Colorado potato beetle.......... wh nig Ape and lime against Hawaiian beet webworm............---.---..--------- and lime against sugar-beet webworm...............----.------- See and lime, dry, against sugar-beet webworm.........-.....-.-+------------ and water against southern beet webworm...-.............--------------- and whale-oil soap aganist Hawaiian beet webworm........-...---------- and whale-oil soap against horse-radish webworm............-..--------- and whale-oil soap against imported cabbage webworm........-.--------- and whale-oil soap against southern beet webworm...........-..-...-.---- and whale-oil soap against sugar-beet webworm........-.-.--...---------- dry, against southern beet webworm............-.--=---4--«..-s= eee lime, and whale-oil soap against imported cabbage webworm........- 5 ae whale-oil soap, and nicotine sulphate against imported cabbage webworm. Parsley, food plant of Porosagrotis vetusta....)... 2 24 ------422--++--2eeee Peach, food plant of Porosagrofs vetusia......:........-------<< ++ Pegomya ruficéps, reared with Pachyzancla bipunctalis from beets....-...------ Phatena angusiahis= Hymenw jfascialis. ..2..~.<-<---222 -1.4+----=_ds eee Phalena 2-punctalis, first name for Pachyzancla bipunctalis.........-.-.-.------ ~Phatena nigrelia— Hymenia fascialas... 2. -225-----5 6% Ha - dain a Phat2na recurvalis— Aymenaa faseialis.......-.. 2222 - +> oe os Le Phalzena undalis, bibliographic reference. ...-.<..,..--------%.+4> oeeeeee Phatens fascialis=Hymenia fascialis... -.. . . - . 5 acto n-ne oe Phorocera erecta, parasite ofi— Lovestege similalis. «25-22 26. -- 22 see 252 2 oan ose ae ae Pachyzancla tipunctalis....-.... -- =. 2. = o4nso- aed- 2 aS ep Phyllotreta bipustulata, association with Hellula undalis in damage to trate crops Phylioireta pusilia on. horse-radish. ........-.----< <2 -4---/--+=<¢ 500-8 Pigweed (see also Amaranthus retroflerus)— food plant of Pachyzancla bipunctalis.............-<-+------<=<<-=s .~ see ee 48 Turnip, Japanese, food plant of Hellula undalis.............-: «ssi aaeeeee eee , 32 Turnips— iodd plantseol Hellule undalis: 22 )2.2.2.: 22.2 Se ee 24, 25, 26, 27, 30 food plants of Porosagrotis vetusta.......-..--- 1 heuiwela «ca ae Be 47 Tyroglyphus americanus, enemy of Hellula undalis.......-.....--+-+++++-+---- 32 Watermelon, food plant of Porosagrotts vetusta............2--20 202 ee eee ese eeen 47-48 Webworm— Hawaiian beet. (See Hymenia fascialis.) horse-radish. (See Plutella armoracea. ) imported cabbage. (See Hellula wndalis.) southern beet. (See Pachyzancla bipunctalis.) sugar-beet. (See Loxostege sticticalis.) ‘‘Wilt”’ disease of Hellula undalis in Hawaii...) ... 22224204). isos bee ee 38 Zinckenia fascialis— bibliographic reference.......:... #oiou)saessatenps)- bs saaile. Dee 15 Zinckenia recurvalis— bibliographic reference... .../....-...-.-:.00.J0.4.i.0<-00 ete eee 15 = Hymenia fascialiay ui. beseeg ss) sy ek alaed-u. ee idss le Dee 13 \ ms s. DI “BUREAU OF ENTOMOLOGY BULLETIN Yo. 110. L. ‘OF HOWARD, Esai and Chief of Bureau ; a, eae? “OR: 4 “GREEN BUG.” am Ceo, Me WEBSTER (neo) ) es In Charge of Cereal and Forage Insect Investigations, ‘ ae . eae : ‘AND FAS Se OW. J, PHILLIPS, EES Entomological Assistant. ; IssuED SEPTEMBER 6, 1912. ~— a Y f \hi- YA Waa Ks ; fy Ome mnernals i S i it oe 5 ‘ ~~ ry % ‘A ems ry. we > = =) NO . + = yr St PE Saye ml! “ay M yseut: i nel ‘WASHINGTON: “i ree ‘GOVERNMENT PRINTING OFFIOR, i Pa, ADR dewn* . ; . 12) Li ) FAs yeh t ‘ x Uy F, rs X , ¢ Br i aa y ¢ J \ tis, * ae < ar wy 4 = 3 = ‘t? ; U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 110. L. O. HOWARD, Entomologist and Chief of Bureau. THE SPRING GRAIN-APHIS ‘OR “GREEN BUG.” BY F. M. WEBSTER, = In Charge of Cereal and Forage Insect Investigations, AND W. J. PHILLIPS, ° Entomological Assistant. IssuED SEPTEMBER 6, 1912. Pome Milas a hint Alii: Hy i Pi ul == A in kiss wee ee A ns cS oo XEN Le AS THE, ee WASHINGTON: GOVERNMENT PRINTING OFFIOE. 1912. ee ee ee BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Maruatt, Entomologist and Acting Chief in Absence of Chief. R. S. Currron, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. CarrrenpeEn, in charge of truck crop and stored product insect investigations. A. D. Hopxtrns, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. WEBSTER, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, in charge of deciduous fruit insect investigations. E. F. Pures, in charge of bee culture. D. M. RoceErs, in charge of preventing spread of moths, field work. Rota P. Currie, in charge of editorial work. MABEL CoLcorD, in charge of library. CEREAL AND FoRAGE INSEcT INVESTIGATIONS. F. M. WEBSTER, in charge. Geo. I. Reeves, W. J. Pumurs, C. N. Arnsure, E. O. G. Ketty, T. D. URBAuNs, Harry S. Suir, Geo. G. AINSLIE, J. A. Hystop, W. R. Watton, J. T. Mone11, J. J. Davis, T. H. Parks, R. A. Vickery, V. L. Witpermutu, E. G. Smyrs, HERBERT T. OsBorN, Puusp LuciInBILL, C. W. CREEL, E. J. Voster, R. N. Wit- son, VERNON Kin@, entomological assistants. NerttiE S. Kiroprer, ELLEN DASHIELL, preparators. MrriaM WELLES REEVES, collaborator. 2 LETTER OF TRANSMITTAL. - U.S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY, Washington, D. C., December 28, 1911. Sm: I have the honor to transmit herewith for publication the manuscript of a bulletin on the spring grain-aphis, popularly known as the ‘‘green bug,” by F. M. Webster and W. J. Phillips, of this bureau. The investigations upon which this bulletin are chiefly based began under a special appropriation made by Congress in the spring of 1907. These investigations have been continued without inter- ruption up to and including 1911. Preliminary reports upon the work were published in Circulars Nos. 85 and 93. The present report, however, is a complete record of the entire investigation, including many aspects of the problem not before touched upon in any publication relating to this group of insects. I recommend the publication of this manuscript as Bulletin No 110 of the Bureau of Entomology. Respectfully, L. O. Howarp, Entomologist and Chief of Bureau. Hon. James WILSON, Secretary of Agriculture. bd wl *. r oe ; Ce r F : “4 . a be 4 4 " ait ’ th . ~ es *, K o. ! 7 y idle 5 “ : i xT ? ; 7 ¥ + 4 , » z +s 4 bar’ % ..4. Fit. ag i si : J . 7 ‘ ”- { Lig i ? , a + (heli cape, : an * eedh Lek . a4 =~ x ' re oxo s 7 , ¥ ‘ a at ed i PGE i esls ti eae : ry { : ; rye ee i , ; v z * : ' Sa at, tig 3 j ‘ Ly; fe . r Sri ™% rs Oo jie a rs : PY i 4 ~— whee ° ; DARE Naty eet é ‘ : , / ' at ht i be A a 1 " 4 4 a vag 444 \ ee eS CAT ET | # as » ; i) Ay p - “ 4 eee ney Kot pt SES eT WE “ih a 4 nly 08 Bepietows cridheyant ] ‘ ¥ . tae a Ss y TF ahh ees y F , “- 4 aad a | ba: i a if I ‘ a ot Pee? Bae e eet! aoe . - : 9 , hy ‘ ; Mews pole i . APE A ee ¥ % .). | . CONTENT Ss : : Page EME ra ag ek ted ce a ps 2 a bt ac ge = ee eg a 11 Earliest observations on the insect in America..................2-2-22-2-2---- Is Sune earee ta PTIBEIE ee 7 2S. 0) ASO A ke 16 Known distribution in the Eastern Hemisphere .............-....--.--------- 16 Known distribution in the Western Hemisphere .................------------ 18 CMMI EEE ANE OE POU Soc aan cia 2s bean a peek AED A ee ania 19 URN ME PO os ng ee a how aan eae A ROINI L o e 21 MMMM OED NO) ono cr ge 3a a ane SRE oe os wi oe oe 21 SIE aE acini i ternpnnagin a Ue AINE Na Oe oT q Losses from depredations in 1907. rca ging 9 x mah oem ON Fk Se ek de ic | Permnauemriesn ie VOM GS . , D 40 EP aS hon Cn Hee Fp UE I MR ot og 41 PRMMIMIa ls: Suisis ) Sintinin ols Os Peay oh. 44 IEMEEIMERENOOIMOMD oo ose eee sre see ee VON LS 44 MUM Pt a cic 5 pk ch a A Nh tin Achat cry Mes NSH dy! Le ee AS 8 44 MRM ee ht Le.) OT wig PIVP EE Fak Ne iw, ca 49 ee MNES inter atehap nop phe ee hie MLA ne 51 NEN ei Doc a acca nec oer mamas ae BRYN TNE 58 wereripiion of the different instars........../).2...02.2..2. 2. 02028 58 eermpnan of ihe summer forms...) ... 0.2.2... ads 22222 LIA. 59 Se a en Mes pacer angen 61 LAD SE TIRE TR ee eR ae a een Uae PE THERE Tere Ae Tab Sa aes a 61 (LUNE 2) 105 TEE Siecle. heeds tee ia ae RRR rere at ety a a re PO eee Ae ac 63 Demet a Pencrations Per Year... 2-2 seen ee ee ee Ae kk ee 63 ’ Age at which females begin reproducing...........---..---------+-----+-- 70 RENTERS ACTION ooo o.oicpn sa rve apuene eG show So Besse ad eee Ls See ee ee 71 NN opens tein Spee wii me iecoee ees ek tats Bars be ot x Awan 72 Mein mn viviparous female....22:..224:27. 0082-022 LLL 73 Fecundity of wingless vs. winged females ................-.--..----.---- 75 ayers number of young produced daily.....:...2.-2..-... 52.22.2202 76 MMMM as ee eel Ric kik aha k Cine weit Gerke ues yates ee 76 PNRM TRIEE SS oo ye ink iy ane a Le A a ee ae Sh Oe 7 RIE re EL abe xo hint nnd tym MEE MEY Rid Catia ae), Ala PAT 78 Oviparous SEE RORMAC IRS SC ees he ce Cb ann We enncnaae we meals ee Me 78 mee at which females begin oviposition..............-.-.2.-.-+-22eee-es- 78 SIRE IOM oo ne eo oes eae ia Sa od oie ad ass enn Ce 79 Feriod of oviposition..............-.-. CE ieee os tee eames ek Seett e 79 RM LEG OE WC, SOROS so hl i olen a win wee Gidea in Sie Ree oe 80 Beeerneih OL OVIPATOME COL. oo. eS 8 od aie ens poe eine keh eee 81 MEN TITER US PSA ee a sea cihiaie sie ng cme Byntinsie-s wim SUM Sr 81 REIRE A WIMHS OM GUAUSION. . . on oo se 3 n= npn a anne ws mie ene ee eee ieee 81 meeerenice of temiperatiire On Giliusion...........--. 20.22.20 ce week een en ee nee 88 6 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.’ Page EOE YS Fao oe aos 3 Sea ek oe Soe eee Seas--s 94 Methodsaand taaterial. ...5.. 255.4222 2 be ee eee tee eon 95 General description of the egg......-.--:------2-s-4-2/--2-3..4- eee 95 Dhrervations. ....2~<-..-.ce.. 2g. Sele ee kee eee ee 97 Summary of embryological development..............-.-.--------------- 102 MUCUTAL CHOMICS.....o2c2efel Use .k oz tes iS ose tee ess oo a... 2 Internal or true parasites..............-.<..-.:s-1. 2.12... 2.3 - 104 A phidius testaceipes Cresg.c..j.2.2. -§ Yi Sted 22... 5-5-2 104 Description and identity ...,...2:----.-..+--.22---22- soe 104 Este hastery....... .- 202-2. 62525. 26245 snes en +e oer 105 OVIROSMOR. 25 onc aie ein du ang ee eee 105 Length of period from egg to adult.................... Meaney 3 106 Effect of parasitism by Aphidius upon development of host.. 106 Effect of parasitism by Aphidius upon fecundity of host..... 107 Movement of larva within the host and manner of attaching it to the plant...:....2..2....4--4..5----.- 09. ee 109 Fecundity - ...<---.a0-26 2020-00650. ++ = = 125 Megorismis 8D). . ~ 2.00 0 doe ee on oe oe oe oe eee ee 125 Aphidencyrtus aphidiphagus Ash ... .. 22.22. 220.1. 1. of 126 Pachymeuron Sp. ..0 «025 > doch. ie ens eee ee ee 127 AOE BP 6 oo ie oa bo ah Sl Sait oe ee ee ee eee 128 Predaceous enemies.............--..-ssescsees42-u> aden ee ee 128 Jatly-beetles....-2 22.5 2.05 36 os ee oo wed oni ee ie ie eee 128 Syrphid flies..............22.---.2.---.cee SOU. Stee 129 Lacewing flies............-.-----.wasssboeeeaviieul 22 bee 132 Cecidomylid@. ..........0<-0c 5-62 2-s0-20nsnans = >> ee ee 133 BiG opine deme ange wwe me lee cae aoe oe 135 Miscellaneous enemies of Toxoptera.........-. sig. /-.20 29 135 Ants and their relation to Toxoptera../ 42:2: J.<4-\2: -.4-0-- 07. Re 136 Remedial and preventive measures....... 5:1 -.0222025+ mhe.t 2. 136 PSR CX periniente. oo iw oe eee 0-08. +2... pee ee 136 Cultural methods...........-5) . SS 348 381° 77° cane seeee! \ S58! #9.1 +10. +8.7------- t — ae S| ceed ay ‘a. on} nel cm ' ‘ eee On June 7, 1884, Mr. Albert Koebele found th wheat plants at Cabin John Bridge, situated in Maryland a few miles above Washington, and about July 1 of the same year the senior JANUARY, 168c. JOal. \ a wW a = 0 uJ (a) ls i ' ‘ egradence nap | ‘, ewes we), i \ 37.8 1424 iy \oo- 403 +45 WT +16) Nei 40; \re! FEBRUARY, 1882. \ L. lee as mee oO. 7485 525 Rn aeGon on 6 / ood. APRIL DIAGRAM I.—Maps of the United States east of the Rocky Mountains, showing normal temperature, upper —, below), for the critical period 1882; above normal (+) in winter and below normal (—) in spring being above normal, and, ? line, and departure therefrom, lower line (+ December, 1881, to May, j (Original. ) favorable for outbreak of spring grain-aphis. J 4 ng cages, placed out of doors at in one of his reari author found it In the latter instance the species showed ference for wheat plants over those of rye, and Oxford, Ind. (see fig. 2). & pre September it in 16 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ was common in the fields on volunteer wheat plants in the same locality and also about La Fayette, Ind. In some fields it was ob- served breeding on the young growing wheat throughout the autumn and early winter up to December 13. On the 30th of December it was still to be found alive in the fields, though not in great abundance. EARLY RECORDS IN EUROPE. The first exact knowledge we have of this insect is its occurrence in excessive abundance about Parma, Italy, in 1847. Five years later, in 1852, Rondani, who described the species during this year, wrote to Prof. Bertoloni under date of June 14, also from Parma, relative to the insect as follows: We have in our city an innumerable number of insects of a species of the Aphis genus, of Linnzus, of the order of Hemiptera. Sometimes and in certain places the number of these insects flying in clouds in the air has been so great as to render them troublesome to people, entering the nose, eyes, and even the mouth, when one can ~ not think how to protect oneself from them. Elsewhere in this letter Rondani stated that he had never been able to find. it on any but graminaceous plants, where it nestled on the leaves. In commenting on this letter of Rondani, Prof. Bertoloni took occasion to say that “‘innumerable specimens of the Aphis — graminum Rondani are seen in the streets of the city of Bologna, and — these have several times entered my nose and eyes when passing rapidly along the canal of Reno.” KNOWN DISTRIBUTION IN THE EASTERN HEMISPHERE. Besides these occurrences in Italy and Hungary (see fig. 3), in 1884 Dr. G. Horvath records an attack on oats in central Hungary, which — took place in June, 1883, and 10 years later, in 1894, Prof. Carl Sajo © records a second outbreak among growing oats, also in Hungary. Schouteden, in 1906, records the species from Belgium, but gives _ no further data except that it affects the Graminacee. Under date of October 7, 1907, Mr. H. Neethling, chief of the horticultural and biological division, department of agriculture, Bloemfontein, Orange River Colony, South Africa, in a letter ad-— dressed to the United States Department of Agriculture, stated that — the wheat aphis was one of the greatest scourges with which the farmers of his colony had to contend, nearly the whole crop having been destroyed by it for several consecutive seasons. Again, under date of September 28, 1908, the same gentleman stated that the pest — had been particularly active that season, it being estimated that more than 50 per cent of the entire wheat crop of the colony had been destroyed by its ravages. This latter communication was accompanied by specimens of Toroptera graminum as well as a small DISTRIBUTION. aM See SOT}TTBVOOT popoodsns ‘,, We AQ Po} VOIPUT OI SOT}I[VOO] WMO et te PZ | fe \ XN = 1 SS : , f nan | Ma t Nis) i Be \ | | i} tj ts jae a (LA am i A dot ee igo Y of NY a Kr Sal \ \ C ’ ran 9 Ke ) f} a pee 4 (‘Teurls11O) “SOIOYASTUIOY WI0]SOM OY] PUB TLIOSBO OT} [10d UT crude 8 Suds oy} JO WOLWNGLISTp OY4 eee denw— a ses a a ies eG 5 eae, Dar 5 Oo Ol at on 0 os! 00) gL 405 i] ohh Seat Bie. »| | Ey | & f ee AD ‘ee ee aa Re iN (rae) \ a evi oF i vl ig we ( J b> Has %y wi) i le D pir) f avi 7» i fy y) J i sid ope f i ¢ Vn {1M VX N un 26675°—Bull. 110—12-—2 ‘“ GREEN BUG.’’ 18 THE SPRING GRAIN-APHIS OR hymenopterous parasite, Aphidius sp., and larve and adults of-a coccinellid, Adalia flavomaculata De G., both of which were observed destroying the aphidids. Under date of October 1, 1910, Mr. C. P. v. d. Merwl, assistant biologist of the same department, stated that another outbreak of the pest had taken place that spring and con- siderable damage had been done. In this communication the state- ment was made that the writer had personal knowledge of the occurrence of the species during the past 20 years, and that farmers had stated that they had always known of its occurrence in that country. It had, however, become seriously destructive during — recent years and at that time farmers were being forced to give up __ growing wheat extensively on account of its ravages. ; In the Agricultural Journal of India’ Mr. H. Maxwell-Lefroy, — government entomologist of British India, stated that the wheat — aphis (Tozxoptera graminum) seeks shelter in the depths of the grass roots; in different ways insects adapt themselves, but these had probably done it gradually, moving in from cooler to hotter areas step by step. From the illustration of this insect accompanying this statement and from specimens later submitted by Mr. Maxwell- Lefroy, it has been found impossible to determine the species involved as Toxoptera graminum. On November 25, 1910, Mr. William Sewall, of Njoro, British East Africa, called at the office of this bureau to complain of the ravages of a green louse or fly which attacked and destroyed wheat on his farm in the above-named locality, situated almost directly on the equator in a prairie-like country at an elevation of 7,000 feet above sea level. A communication was received from Mr. Sewall bearing date of August 22, 1911, accompanied by specimens, in which he stated that the ravages now extend over an area of 700 acres. He also stated that his neighbor, Lord Delamere, who had not been troubled previously, experienced severe losses over an area of about 4,000 acres. The specimens accompanying Mr. Sewall’s letter have been determined as Toroptera graminum by Mr. J. T. Monell. With these records of the known and probable distribution of Toxoptera graminum, it does not seem improbable that if the minute insects of the family Aphidide were carefully studied this species would be found generally diffused throughout the temperate and — tropical regions of the world. | KNOWN DISTRIBUTION IN THE WESTERN HEMISPHERE. With reference to the distribution of this insect in the Western Hemisphere (see fig. 4), it can be said that it has only been studied in the United States. Its occurrence in western Canada is well established. On the south it is known along the Mexican border from the Gulf of 1 “Tmported insect pests.” Agricultural Journal of India, vol. 3, part 3, pp. 243-244, July, 1908. ~~ THE OUTBREAK OF 1890. | 19 ¢ Mexico almost to the Pacific Ocean. It has not actually been found in Mexico and no one has searched for it there. Wheat in Mexico is said to have been injured by a ‘‘green louse,” and it is reasonable to suppose that the insect may occur far to the southward of its present known range of distribution. Its entire absence from eastern Canada and northeastern United States, except in eastern Massachusetts near Boston, where it seems to have been found by Mr. Paul Hayhurst in September, 1908, will be noted. i > THE OUTBREAK OF 1890. (Fig. 5, p. 20; Diagram IT, p. 21.) Up to the year 1890 in this country the very destructive nature of this insect had not yet become apparent; hence it had not received the close attention that, as we now understand, it justly deserves. any "el ba oe ‘ ) i { ' ' aN ' 1 te Wi noite FS Ss i i ® i ee ' oy — g St OD . e Fia. 4 -—Map showing the known distribution of the spring nig in the , United States and Canada. (Original.) While the senior author was and had been engaged in grain-insect investigations in Indiana during the six years following its discovery by him at Oxford, the species was not looked upon as one of those deserving especial attention; therefore from 1884 to 1889 no notes were made upon it, and no references to it are to be found in the correspondence of the Division of Entomology. Mr. J. T. Monell, now of this bureau, however, has specimens in his collection from Illinois, taken in 1886. During November and December, 1889, the insect was again observed in such abundance in fields of young wheat about Lafayette, Ind., as to attract the attention of the senior author, who found it repeatedly on young wheat in the fields during the entire winter. The influences of mild or high temperatures during winter, especially eS 20) THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ in the South, and low temperatures during spring months were carefully observed and set forth in a report published later. As early as the middle of January, 1890, it was reported by Mr. P. C. Newkirk as killing the young wheat about Jalapa, Tenn., and on the 26th of the same month Mr. B. F. White, of Mebane, N. C., reported it as ruining both wheat and oats in his neighborhood. Mr. J. L. Fooks, writing on the same date from Era, Tex., stated that the - insect had played sad havoc with the wheat in his neighborhood, while April 7 Mr. D. J. Eddleman, Denton, Tex., complained of the pest destroying the wheat. Writing in 1901 Mr. H. K. Jones, Valley View, Tex., stated that the insect appeared there about 10 years pre- T graminum T.graninum ; invasion |9O3. invasion |907 Fic. 5.—Maps showing areas covered by outbreaks of the spring grain-aphis during the years 1890, 1901, 1903, and 1907. (Original.) vious and killed about all the wheat in the county. From this and other correspondence, accompanied by specimens, it seems that wheat in Cooke, Grayson, Collins, Denton, and Wilbarger counties, Tex., was more or less damaged by this pest.2 No reports are at hand showing injuries to wheat or oats in what was at that time Oklahoma and Indian Territories, for the reason that little of either of these grains was at that time grown. But we now know that grains were not essential to its presence in that country. In Missouri the situation was more acute and strongly indicates that the pest was present in southeastern, Kansas and northern Arkansas. According to Mr. Monell’s notes, the pest completely Te Reside Life, vol. 4, pp. 245-248, 1892; Bul. 22, Div. Ent., U. S. Dept. Agr., pp. 64-70, 1890; Yearbook U.S. Dept. Agr. for 1907, pp. 239-241. 2 Insect Life, vol. 3, p. 75. 21 THE OUTBREAK OF 1890. destroyed a field of 60 acres of oats belonging to Hon. Roland Hazard at Mine Le Motte, situated about 100 miles south of St. Louis, Mo., 4, < t= S457 ASA 435 “3s — pecan y 263 . i ie Sa = 514 pF #22 ' Ne ro —e-- . ----5 te-2-e 8 4 i] ‘ i *oqondon oe a ' + 1 ‘ ' ' ' a Es ee » 1889. +B +1 * DECEMBER . 3 \ SSS Sees 1 ' 1 ' 4 ' t ' 1 J. epee. UY {2: -09 Y, 1890. FEBRUAR 1. -07 £ #25 ay ’ ' ‘ 1 4 ' J ‘ J a a MAY 1890 APRIL 1890 D1aGRAM TI.—Maps of the United States east of the Rocky Mountains, sh 1 temperature, owing norma lower line (+, above normal, and —, below normal), for the ? and departure therefrom critical period December, 1889, to May, upper line, spring 1890; above normal (+) in winter and below normal (—) in favorable for outbreak of spring grain-aphis. (Original.) being In Missouri the situa- to have been pretty clearly set forth by Colman’s Rural the observations being made June 10, 1890. In the cultural paper of the Southwest. ing agri tion appears World, then the lead 99 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ issue of that publication for June 12, 1890, the following statement is made: The oat crop in the vicinity of St. Louis and probably extending a hundred miles in every direction is being completely destroyed this season by an aphis, commonly called, we believe, the Texas louse. The oat fields look brown and bare, this little green insect sucking the juices and sapping the vitality of the plant. it increases with amazing rapidity, fully as rapidly, we judge, as the hop louse, swarming in every direction and carrying destruction in its path. The only thing they seem to feed upon is the oat. In the issue of the same publication for June 19, a week later, the following statement is made: The oat crop this season will be almost a total failure in St. Louis County. Hundreds of acres have been totally destroyed by the aphis, or plant louse, the depredations of which have been so widespread and effective that only a very small per cent of the crop will mature. Hundreds of farmers have despaired of the crop entirely, and have plowed up their oat fields and planted corn instead. | | The Weather Crop Bulletin of the Missouri State Board of Agri- | culture for the week ending July 4, 1890, gives the following estimates of the oats crop throughout the State. Northeastern Missouri, 63 per cent; northwestern Missouri, 70 per cent; southeastern Missouri, 25 per cent; central Missouri, 30 per cent; southwestern Missouri, 54 percent. As another writer describes it, the damage was most serious south of a line drawn diagonally across the State from the northeast to the southwest corner. The statement made in Colman’s Rural World to the effect that the oats crop within a radius of a hundred miles of St. Louis had been completely destroyed by the oats aphis or ‘“Texas louse” would include within this radius territory nearly half way across southern Illinois. Mr. B. F. Johnson, of Champaign, IIl., an agricultural writer, who appears to have traveled over the country quite extensively and observed the situation closely, writing to the Country Gentleman under date of June 24, sized up the situation as follows: For some weeks after it was seen above ground, the oat crop looked well and promised well, and this continued to the first or about that date in June. Since then oats have been going behind hand, with the threat now over them that all the crop has been more or less seriously reduced in yield and a considerable portion will be lost. In fact, the oat aphis, after ruining the oat crop south, has appeared on the black soil in force and nothing less than many and heavy rains will arrest his progress. As before reported, the dry weather in May favored a light growth of straw, as in 1887, and hopes were entertained that long heads of sound grain would result. Such would have been the case had not the aphis appeared and sucked a part of the life-blood of the plants. The present appearance of a majority of oat fields—the acreage on the black soil coun- ties is an enormous one—is rather uneven as to growth, color, and measure of develop- ment, a part of which is owing to the greater or less fertility of the soil, but chiefly to the depredations of the aphis, that takes the weakest plants growing on the thinnest land. : In the issue of August 14 of the same publication, Mr. John M. Stahl, of Adams County, Ill., states that in western Illinois the only \ oe THE OUTBREAK OF 1890. 93 cause of the failure of the oats crop recognized was the green louse. Directly upon this point his statements were as follows: We never had a better prospect for oats until the green louse began its work. Some fields were not attacked by the louse, though it infested surrounding fields. From the fields not attacked by it there was a splendid yield of oats; while, of course, the other fields yield scarcely anything. In every township there were a few fields that were not attacked by the green louse and that made a good yield. The fact that those fields not attacked by the green louse invariably made a good yield, while those that were attacked made a poor yield, is proof that in this part of the State, at least, the green louse was the prime cause of the failure. This feature of the apparent immunity of some fields from attack while others adjacent were destroyed has since been observed again and again, especially along the borders of a serious invasion, which was precisely the stuation in western Illinois at the time indicated by Mr. Stahl. In Indiana the senior author investigated the outbreak personally, and while the pest was present as far north as Lafayette, there was little if any damage from its attacks north of Indianapolis. In the neighborhood of Franklin on June 25 many fields were badly damaged, but the injury was much more severe to the southward and at New Harmony, Ind., on June 11, the oats crop was ruined. The same was to be said of the country across the Wabash River in Illinois. While both Toxoptera and Siphonophora were present in most cases the former largely outnumbered the latter and there was no difficulty in properly crediting the destruction to Toxoptera. The occurrence of this insect in southern Ohio was greatly obscured owing to the fact that it was, as elsewhere, confused with Macrosiphum granaria Buct. Clarence M. Weed, writing for the Ohio Farmer (see issue of July 12, 1890), states that in Ohio the grain plant louse had been reported from Pickaway, Clermont, Butler, and Franklin coun- ties. It seems, however, that in Clermont County, according to Mr. Kd. C. Ely, the plant lice were at work as early as May 30. In a later issue of the same paper, July 19, 1890, Hon. Abner L. Frazer, of Clermont County, Ohio, stated that the aphidids were very numerous in his fields on June 9. While it is impossible to say with absolute certainty that all damage was due to Toxoptera, nevertheless Waldo F. Brown, writing from Butler County! on June 19, says: Oats are in a critical condition. The leaves have turned red. It has not the appearance of rust, looking more like the firing of a plant in dry weather, and I should not wonder if the crop proved a total failure. In both Illinois and Missouri the aphidid causing the damage was termed the ‘‘Texas louse,’ and wherever a technical name for it was used at all it was called Siphonophora avenze Fabr. Because Toxoptera was at that time but little known, and owing to the 1 Country Gentleman, June 26, 1890, p. 506. “— | ae 94 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ extreme difficulty in separating its young and its wingless adults from those of other species, it would seem that more or less damage to the oats crop might be with justice accredited to Toxoptera in- Butler, Miami, and Clermont counties in extreme southern Ohio. THE OUTBREAK OF 1901. (Fig. 5, p. 20; Diagram ITT, p. 25.) The outbreak of 1901 was less extensive than that of 1890. Little damage was reported south of Waco, Tex., but from this point northward wheat was more or less injured, and oats were destroyed to the northward into what was at that time Oklahoma and Indian Territories. The farthest point to northeast at which damage was reported, with specimens of the depredator, was Saratoga; in extreme southwestern Missouri. The specimens accompanying correspond- ence from Texas and Oklahoma gave ample proof of the identity of the destroyer, which in Texas alone ruined grain to the extent of several million dollars. In central Texas the ravages of the pest began to attract attention early in March, while the report from Missouri came under date of April 30. It will be noticed that the direction taken by this invasion followed very closely that of 1890 (see fig. 5), beginning, however, farther south in Texas, not extending so far to the northeast, and dying out, as it were, earlier in the season. These phenomena will be explained farther on under meteorological influences. THE OUTBREAK OF 1908. (Fig. 5, p. 20; Diagram IV, p. 26.) As foreshadowing the impending outbreak of 1903, as early as November 26, 1902, Mr. J. F. Ordman, writing from Windthorst, Tex., complained to this bureau of the ravages of the green louse, stating that it had destroyed several small areas in his wheat field and that it was reported generally prevalent in his neighborhood. This outbreak was, however, an incipient one and resulted in little injury, the seriously infested areas being confined to northern Texas, exclusive of the ‘Panhandle,’ with possibly the country in the then Oklahoma and Indian Territories bordering the Red River, and in South Carolina. While the outbreak was thus limited in area, the natural enemies of the pest in the West evidently fell far short of completely subjugating it. In March, 1904, Prof. E. D. Sanderson and Mr. E. C. Sanborn found it in Grayson County, Tex., sufficiently abundant to work serious injury in the fields of young wheat and oats, in some cases the destruction of the growing grain 25 THE OUTBREAK OF 1903. being complete. The same gentlemen reported the pest present in . a ha-- --- ee soenadonyewn L..i J limited numbers during the spring of 1904 in Collin, Hunt, and o> ---- DECEMBER, 12900.\ pepoendo...., p-----...-4 . aeer \=3.2 he----. FEBRUARY, |90!. ~---+----4 c. ete donna i. Sa | ‘ j Preene----- 2.0 = E I9OI. APRIL D1aGRAM III.—Map of the United States east of the Rocky Mountains, showing normal temperature, for the critical period lower line (+, above normal, and —, below), to May, 1901; above normal (+) in winter and below normal (—) in spring being ? upper line, and departure therefrom December, 1900 , (Original.) favorable for outbreak of spring grain-aphis. This year, however, the parasites evidently did rvice, aS at vi ® ‘Ss | = S 3} a é tewright, Grayson County, Tex., on March 10, 1904, Mr. Sanborn found that 60 per cent of the Toxoptera more effective se $9 GREEN BUG. 26 THE SPRING GRAIN-APHIS oR $$ @O os gs. oo ae 4 a ee oo 242 . A = a aS) i eb) 6A a es = > oo o a & 8) is . 2 dG S ap a= ies| ad eS 5 qa m4 DM o & 3 eH NM = & ae : fas] 5 A 2 = So o — f= | | 225 3.2 2.9% Ou | on i) tol at died sof JANUARY, 1903. rw) oO 2 a Wi : Mm ra) Se ee es uc at s-ya=—J_ a ing —-—--a MARCH.1903 }+--~------ 545 55.4 \ 0.2 { f q q —Map of the United States east.of the Rocky Mountains, DIAGRAM IV showing normal temperature, and —, below), for the critical period December, 1902, to May, 1903; above normal (+) in winter and below normal (—) in spring being ? (Original. ) the fields of wheat and oats without find upper line, and departure therefrom, lower line (+, above normal favorable for outbreak of spring grain-aphis. pa ee at on gS = ~ - | a fas) 2 = fas] re S (2) or] ~~ i] S P4 nN ie) oe 2) o jor n 2 a — — i) Safe | jo) io) — are o>) | 62) 3 c o ae) in DM heal S) ® DM ei oN A - ; 7 ge: ® mM Py cas 48 was doubtless still present in very limited numbers. ¢é THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’ 97 THE OUTBREAK OF 1907. (Fig. 5, p. 20; Diagram V, p. 28.) _ The outbreak of 1907 was by far the most serious and widespread that has occurred in the United States up to the present time. Start- ing in east-central Texas, the invasion swept northward and east- ward, covering a somewhat fan-shaped area, through Oklahoma, Kansas, northwestern Arkansas, Missouri, and across Illinois to within 60 miles of Chicago. Though possibly not doing so much damage in the Ohio Valley as in 1890, it extended westward through Oklahoma and Kansas into southeastern Colorado. While not especially injurious to oats and not at all to wheat in the States of Nebraska, Iowa, Minnesota or the Dakotas, the late Dr. James Fletcher states that in Canada it actually did some damage in Sas- _katchewan. Less damage was probably done in Indiana and Ohio _ than in 1890, though the ravaged area in general followed the ground covered by the previous outbreaks; in this latter case the northeastern terminus of the seriously ravaged area appeared to be confined more closely to the upper Mississippi River and Illinois River valleys than to that of the Ohio River, thus sweeping more broadly to the northward. On the Atlantic coast fall oats were destroyed or badly injured in South Carolina, and both wheat and oats in western North Carolina. In Virginia, Kentucky, and Tennessee neither grain was, as a rule, seriously damaged. The areas shown in figure 5 indicate all injury, even though slight, in occasional and widely separated fields. In the valleys of the upper Missouri River and the Red River of the North there was little or no injury, and it seems doubtful if the pest occurred in that section prior to this outbreak. Forebodings of trouble from this pest came as early as November and December, 1906. According to copies of Mr. Sanborn’s notes, as placed at our disposal by Prof. A. F. Conradi, the species was sent to the Texas experiment station from Howe, Grayson County, Tex., where it occurred on oats, as early as November 14, 1906, and one day earlier from Allen, Collin County, of the same State, where it -was present in great numbers attacking volunteer oats plants. On December 22, 1906, it was sufficiently abundant about Plano, Collin County, Tex., to destroy oats in patches in the fields, its natural enemies at the time being in a dormant condition because the tem- ‘perature had not. reached and remained at a degree that would render them active. During January and February, 1907, these conditions continued, the Toxoptera breeding and spreading unre- strained by its enemies, so that the area over which it was becoming destructive continually increased. Rumors of injuries by this pest came to us early in January, 1907, from east-central Texas, where the ‘‘green bugs’’ were reported to Mr. W. D. Hunter, in charge of cotton boll weevil investigations of ~~ y~T © ee a — : A AIO A ON i AE CA 28 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.”’ this bureau, as attacking fall oats. During this month in Texas east : of a line drawn from near Gainesville through Abilene and San --- . —e---5 meen : —————— ‘an’ 4458 as2 +42 1 +30 Faa6 .. 7 / SS fea og ge D1acRam V.—Map of the United States east of the Rocky Mountains, showing normal temperature, upper line, and departure therefrom, lower line (+, above normal, and —, below), for the critical period December, 1906, to May, 1907; above normal (+) in winter and below normal (—) im spring being favorable for outbreak of spring grain-aphis. (Original.) Antonio to Galveston the temperature -was 9° F., above the normal. Within this area was a smaller one, the boundaries of which may be — indicated by a line drawn from Texarkana to Fort Worth, Waco, and ~ THE OUTBREAK OF 1907. 29 Joaquin. Over this latter area the temperature for the same month was 12° F. above the normal, and within this latter area the pest first began its work of destruction. For reasons to be explained later in their proper place, the spread of the pest was much more rapid to the north and northeast from north- central Texas than it was in the opposite direction. In March the pest was found generally present about San Antonio, Kerrville, Menardville, and New Braunfels, of that State, but because of the small acreage of grain grown in that section the damage was not serious. Indeed, the same may be said of the country west of a line drawn from western Wilbarger County to the Brazos River at Round Timber, Baylor County, and west of the Brazos to and except about Waco. East and north of this the damage ranged from serious to total ruin. As early as March 6 it was also reported to the bureau as destroymg wheat in the vicinity of Summers, northwestern Arkansas. This was probably due to local causes, uninfluenced by invasions of swarms of winged viviparous females that were being continually swept from off the more disastrously affected country to the southwest and drifting toward the northeast. Mr. C. N. Ainslie was instructed to proceed from Washington, D. C., to this part of the country, where he arrived on March 16. On March 15 the Texas Grain Dealers’ Association, through its secretary, Mr. H. B. Dorsey, made an appeal to the chief of this bureau for aid in devising means for destroying the pest and curtailing or preventing its ravages. In response to this appeal the junior author was dispatched to Fort Worth, Tex., arriving there on March 26. The situation here was found to be most serious. Hundreds of acres of both wheat and oats had been wiped out of existence; in many cases fields were observed where it was impossible to find a living plant, and as a rule numbers of such fields were being plowed and prepared for other crops. Plate I, figure 1, shows a field entirely destroyed. The weather at this time was hot and dry and Toxoptera appeared to have been entirely overcome by its natural enemies. ~ On March 25, 1907, a telegram was received from the Roosevelt Grain Elevator Co., of Hobart, Okla., reporting serious attacks from -Toxoptera and Fopecline to ae Saas of Agriculture for assist- ance. The junior author was at once instructed to proceed to Hobart, where he arrived April 1, remaining until April 5. This point ap- _ peared to be on the western border of serious injuries by the pest, and the situation was therefore not so grave as in Texas. From the junior author’s observations it appeared that much of the damage that was being done was caused by insects which had drifted into the fields and not from individuals originating therein. This was evi- -denced by the fact that in wheat fields where a part had been sown ce 30 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ early and the remainder later in the season the latest sown was very much more seriously damaged than that sown earlier. About the i only portions of the early-sown part of the field to suffer serious injury were on the poorest soil. In short, the Toxoptera was found ~ to be working its greatest damage in late sown or pastured wheat fields and among the young oats. Natural enemies were busily at work and apparently fast overcoming the pest. In the meantime Mr. Ainslie had found the pest destroying wheat in spots in the wheat fields about Fayetteville and Summers, Ark., March 16 to 20, as well as at Chandler, Okla., March 24, and at Guth- rie, Okla., on March 25. Near the latter place large circles were observed in the otherwise green fields of wheat. In the center of these circles the red soil was exposed by reason of the killing of the wheat plants, and these exposed circular areas were bordered by a band or girdle of yellow half-dead wheat plants, where the Toxoptera were most abundant. (See Pl. I, fig. 2.) In another field in this vicinity there was a stack of oats straw of the previous year, and from this stack a dead area extended at least 100 feet to the south. This area was nearly circular, with the stack almost in the center of the circumference. Near and surrounding the stack was an area of dead volunteer oats, and beyond this a stretch of bare ground indicated where wheat had once stood. From people occupying a house near by something was learned of the previous history of this straw stack from which Mr. Ainslie determined that volunteer oats had sprung up after thrashing in 1906; these oats turned brown soon after, causing some wonder among farmers, and during the winter the plants died. The trouble spread to the wheat adjoining and here the wheat plants died early inthe spring. There was here seemingly a repetition of the conditions in the fields about Summers, Ark., where Toxoptera infesting volunteer oats extended its destruction from these to the wheat near by. On March 26, between Guthrie and Kingfisher, Okla., Mr. Ainslie observed that the dead spots in the wheat fields were a striking feature of the landscape, for in the sunshine the bright green of the young erain made a striking contrast with the yellow-rimmed red circles where the Toxoptera had destroyed the wheat. Occasionally a field was free from these areas, but more of them were frightfully spotted inthismanner. A field of wheat that was pastured more closely than most grain fields lay in the edge of Kingfisher and showed the attack of the Toxoptera worse than in adjoining grain. On March 27, at Kingfisher, Toxoptera was flying by the millions, the air being full of the migrants, and farmers who drove to town were covered on the windward side to their annoyance. The aphides seemed for the most part to fly low, but the wind hurried them at such a rapid rate that they might easily have been invisible when higher in the air. On the | = Ss ee SS, : ' ; : THE OUTBREAK OF 1907. 31 following day large numbers of Toxoptera were on the wing, always moving north. In a field of oats, sown in February, the plants had hitherto been very thrifty, but at this time in a great many of the drill rows the plants were about dead for a space of 8 or 10 feet, and in case of later sown fields the plants were all fast dying under the attack. There was becoming gradually apparent a fact of consider- able importance regarding the relative number of winged forms in the fields. In oats fields where the food was succulent and good it was difficult to find a single pupa, while in older and less succulent wheat, perhaps within a yard of the oats, pupz would form 75 or 80 per cent of the population of the blades. This was afterwards verified repeatedly by observation and by actual counting; indeed, through- out the entire spring this fact seemed to be substantiated. From March 31 to April 3 Mr. Ainslie carefully examined fields of wheat and oats in the vicinity of Wellington, Kans. He found wheat fields invariably evenly infested with Toxoptera though nowhere in any great numbers. Many of these were winged adults, indicating « that they were migrants, and the young about them clearly evidenced a recent invasion. No dead areas were observed in the fields north of Pond Creek, Okla., but between Kingfisher and this point the circular dead spots were plainly in evidence. These dead areas, (Pl. I, fig. 2), from their regularity in the field, plainly indicated the rows of oats shocks of the fall previous and were clearly to be seen where the oats had been shocked and allowed to stand through a period of wet weather. This generally produced a vigorous growth of volunteer oats when the shocks were finally stacked or removed, and in this young grain the Toxoptera seem to have had an early start. In some cases it was easily possible to observe these spots all over a field, although the volunteer oats were rarely entirely killed—perhaps only changed to a reddish color. The infestation seemed to be more marked in the wheat in the vicinity of these spots, and later the Toxoptera swarmed about these places. _. It may be noted that these observations of Mr. Ainslie in north- "western Arkansas, southern Kansas, and northern Oklahoma were made upon the same dates as those of the junior author about Fort Worth, Tex., and at Hobart in southern Oklahoma, thus visi ; a tit nde of als: 400 miles. | Mr. Ainslie returned to Kinefisher, Okla., April 3, and was joined peere by the junior author on the 8th of the same month, where a “number of experiments were carried out in the field, the rani of which are given in the proper place. By the 8th of the month para- sitized Toxoptera was found excessively abundant in the fields, in evidence of which a case was noted where a section of a leaf of wheat 14 inches in length carried 43 brown, parasitized individuals. Mr. Ainslie left Kingfisher, Okla., for Wellington, Kans., on the following 7 ¢é 32 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.’’ day, taking with him more than a bushel of these wheat plants with the parasitized Toxoptera thereon and on the t1th this material was put out in a field near Wellington where the Toxoptera was the most plentiful, in order to determine if it was possible to increase the limited numbers of parasites at the time observable in the field, so as to expedite the work of the latter in overcoming the pest. This was the first artificial introduction of Aphidius into Kansas, six days after which Prof. S. J. Hunter began distributing parasites. The following day a second lot of material sent from Kingfisher by the junior author, some of it carrying as many as 100 parasitized Toxoptera to a single blade of wheat, was distributed in a wheat field, also near Wellington, by Mr. Ainslie, some of it being placed in bunches to protect it from the weather and the remainder scattered over the ground among the growing wheat. The Aphidius already observed in the fields on the 11th appeared to be on the increase, as many as 11 parasitized individuals being observed on a single growing leaf, though but few of the adult parasites were observed abroad in the fields. On April 18 parasites were sent to McPherson and on May 18 to Manhattan, Aphidius being present in the fields at the time © of introduction. These introductions will be taken up in detail farther on in this bulletin. On April 12 a letter was received from Mr. J. A. Akers, at Hooker, Beaver County, Okla., stating that the ‘‘green bug”’ was destroying his wheat. The junior author, being notified of the outbreak, pro- ceeded there, arriving on April 24, and found that Mr. Akers’s field was the only one in that locality that had been injured, and, in faet, it was outside the zone of destructive infestation in this State. This field comprised 52 acres, over a portion of which oats had been sown the previous year, while cowpeas had been grown upon another and much smaller part. Volunteer oats were plentiful over the first mentioned area. One of the infested spots was located among the wheat and volunteer oats, while the second spot was in the area pre- viously devoted to cowpeas. There were no other injured spots in the whole field, although an occasional Toxoptera could be found here and there over the field, which was also true of other fields in this vicinity. It is a significant fact that young plants of Agropyron occidentale Scrib. were found growing in both of these spots and they were as badly infested as the wheat plants. A few parasitized Toxoptera were found, but the parasites were apparently dove slowly on account of cold weather. The junior author went to Indiana the latter part of the first ‘wsdl in May, but was recalled to Kansas and reached Manhattan onthel18th, where he was met by the senior author, and a final experiment for the ~ artificial introduction of parasites was here planned and begun at — this time, the results of which are given farther on in the proper place. Bul. 110, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE |. ae *, Mg : . t \ I, Fig. 1.—WHEAT FIELD TOTALLY DESTROYED BY THE SPRING GRAIN-APHIS (TOXOPTERA f. GRAMINUM). 7 Contrast with uninjured portion of field shown in figure 2. (Original.) i i li : i i ? a ae eat pe at HY h,.5 i" Nh Ni . ND : + . a ¢ : ck hi ays | Fic. 2.—CIRCULAR SPOT IN WHEAT FIELD WHERE GROWING GRAIN HAS BEEN DESTROYED BY THE SPRING GRAIN-APHIS. The growing grain on these circular areas is as completely destroyed as in the field shown in figure 1. Increasing in size and number, the spots come to include whole fields. (Original.) FS a A ed at Fi , THE OUTBREAK OF 1907. oo From here the junior author made a trip into northwestern and north- eastern Kansas and south-central Nebraska to determine the north- ern limit of destructive infestation. The following places were visited: Solomon, Dickinson County, Kans.; Beloit, Mitchell County, Kans.; Lenora, Norton County, Kans.; and Kearney, Buffalo County, Nebr. The fafeetation at all of these places was very slight and no © damage was done. At two places only, Solomon and Beloit,, were parasites found. The senior author in the meantime proceeded to Great Bend, Barton County; Dodge City, Ford County; Garden City, Finney County; and Syracuse, Hamilton County—all in Kansas. The object of this trip was to see how far Toxoptera had spread to the westward. It was found at all of the above points, doing consid- erable injury; at Syracuse an unirrigated field of oats of 10 acres was found bordering an irrigation ditch. Along this ditch was a ragged border from 10 to 30 or 40 feet in width of vigorously growing oats where the ‘‘green bug”’ had apparently done no injury, while beyond this border, where the moisture from the ditch had not penetrated, the loss was total. In another case in the same locality, a part of the wheat in an unirrigated field came up in the fall and the rest not until the following spring; the former was uninjured by ‘‘green bugs,”’ while the latter was killed. From Syracuse the senior author proceeded to Wellington, Kans., to join Mr. Ainslie. In a letter dated June 5, 1907, Prof. C. P. Gillette states that he made a trip into the Arkansas valley early in the spring and found Toxoptera doing very serious injury to wheat fields; to such an extent was this the case that he advised some of the farmers to plow up some of their fields and plant other crops. Following this trip there was a heavy snowstorm and the ‘‘green bugs”’ were greatly diminished in numbers, though at the date of his writing (June 5) Toxoptera was abundant: i in the fields. On July 9 Prof. Gillette sent us badly Perea Toxoptera on blue grass from Fort Collins, Colo., with the statement that the “green bug” had largely DSappeaed = the grain fields in that locality. Mr. Ainslie remained in the vicinity of Wellington, Kans., from the last week of April to the 21st of May, at which date he was jomed by the senior author and went south to Kingfisher, Okla. The condi- tions found there were serious in the extreme, most of the grain fields being bare and many had been plowed and displaced by other crops. Between Wellington, Kans., and Kingfisher, Okla., a strip of country was encountered by them about 30 miles in width, beginning above Medford, Okla., with Pond Creek about midway between, and extending almost to Kremlin, Okla., over which the injury from Toxoptera was not nearly so great as in the country both to the i Si aa ee 26675°—Bull. 110—12——3 ¢6 34 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.’’ north and south. This area was investigated by Mr. Ainslie on the 23d of May. There was plenty of evidence of Toxoptera attack. Some fields were killed outright and others badly spotted, but a number of fields were little injured. No particular reason could be assigned for this condition of the fields, and this area, with a few ‘interruptions, extended on to the west indefinitely. This belt extend- ing across the wheat-growing section of Oklahoma was evidently observed by Mr. Sanborn, who stated in his notes, copies of which were furnished by Prof. Conradi, under date of March 29, 1907, “Northern boundary of parasitized infestation is between Kingfisher and Enid.” Again, under date of March 30, “Pondereek, Okla. Doing great damage, in large spots, here. There lies a peculiar fea- ture between this and Kingfisher. At these two points the infestation was about equal. Enid has no damage yet.” Mr. Ainslie now started northward to trace Toxoptera to its most northerly point in the United States and to learn to what extent its parasite occurred with it, stopping at the following places: Kingman, Kingman County, Kans.; Hutchinson, Reno County, Kans.; Sterling, Rice County, Kans.; Scott, Scott County, Kans.; Great Bend, Barton County, Kans.; Oakley, Logan County, Kans.; Colby, Thomas | County, Kans.; Goodland, Sherman County, Kans.; Manhattan, Riley County, Kans.; Lincoln, Lancaster County, Nebr.; Plainview, Pierce County, Nebr.; Dixon, Dixon County, Nebr.; Sheldon, O’Brien County, lowa; Mason City, Cerro Gordo County, Iowa; Dodge Center, Dodge County, Minn.; Rochester, Olmsted County, Minn.; Brookings, Brookings County, S. Dak.; Aberdeen, Brown County, S. Dak.; Fargo, Cass County, N. Dak.; East Grand Forks, Polk County, Minn.; Hallock, Kitson County, Minn.; Grafton and Park River, Walsh County, N. Dak.; Larimore, Grand Forks County, N. Dak.; and _Casselton, Cass County, N. Dak. He reached the last-mentioned place on August 5, after which he returned to Washington, D. C. _ Except at Kingman, Hutchinson, Sterling, Great Bend, and Man- hattan, Kans., Mr. Ainslie found but little damage resulting from Toxoptera, the most striking feature being the fact that parasites were found associated with Toxoptera at each point visited with the following exceptions: Goodland, Kans., very few Toxoptera in this immediate vicinity; Lincoln, Nebr., no Toxoptera found; Brookings, S. Dak., 2 to 3 Toxoptera only seen; Aberdeen, S. Dak., no Toxoptera found; Fergus Falls, Minn., only 1 Toxoptera observed here. The significant feature of this is that no parasites were introduced artifi- cially at any of these points outside of Kansas. From statements made by Prof. J. M. Stedman, who was professor of entomology at the University of Missouri at this time, it appears that Toxoptera was swept over the border from Oklahoma and Kansas into southwestern Missouri. Prof. Stedman states that there were from six to eight counties in the southwestern corner that were very - mo '\ THE OUTBREAK OF 1907. 35 badly infested; outside of these counties the infestation was slight. He received very few if any reports of its occurrence north of the Missouri River. It probably occurred in the northern part of the State also, as the bureau received a report, with specimens, of injury to oats at Weaver, Lee County, Iowa, and Mr. C. N. Ainslie found it occurring in small numbers at several points in northwestern Iowa. From reports received by this bureau it seems that Toxoptera, was very abundant in northern Illinois, confining its injuries chiefly to oats. Mr. Edgar McGee, of Sciota, McDonough County, IIl., sent us specimens July 5 which proved to be Toxoptera, and in a letter dated July 29 he stated that it was very widespread, that his and adjoining counties were badly infested, and that some fields of oats were so seri- ously injured that the owners had plowed them under and planted other crops. The yield in that locality, from Mr. McGee’s report, seems to have been greatly reduced. At Sandwich, Dekalb County, Ill., there was apparently consider- able damage to oats; no specimens were received; the injury in all probability was, however, due to Toxoptera. To quote from a letter from Mr. Clark Graves, bearing date of July 12: I have today mailed to you, under separate cover, a fair sample of the oats of this vicinity, and I think from general appearances that the crop will be shortened half on account of the green bug. The bugs have now disappeared, and it would seem that the late oats have suffered considerably more than the early ones. ] f There were no specimens of plant-lice in this material from Mr. Graves. A report, with specimens, was received from Manteno, Kankakee County, Iil., which stated that that section had suffered considerably from ‘‘green-bug”’ attack. _ We have only one record of serious injury from Indiana in 1907 that can without doubt be attributed to Toxoptera. This was in a small field of oats just outside the limits of Indianapolis. The junior author examined this field and found that over an acre had been seri- ously affected, part of it being entirely destroyed. The “green bug” disappeared from the oats before the latter headed out, probably overcome by Aphidius and other enemies. This infestation appar- ently originated from rank bluegrass growing along one side of the , field. Later in the season, when the oats had been harvested, Tox- optera could be found along this margin on the bluegrass, where the ‘Sexes appeared and eggs were produced. Toxoptera was found at other points in Indiana, but only in small numbers. _ Mr. T. H. Parks, of this bureau, states that in the latter part of dune, 1907, the oats on his father’s farm in Pickaway County, Ohio, were badly damaged by aphides. He states that parts of some fields in the neighborhood were scarcely worth cutting. Aphides were very abundant on the plants and parasitized aphides were very plentiful also. The oats plants that were badly infested turned brown, and i 36 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ before they were ready to head out the aphidids disappeared. This — was probably due to the presence of the parasites. Wheat was not — attacked or injured by these aphides. Mr. Parks did not have any © of this material identified, and we can not say absolutely that this © was Toxoptera graminum Rond., but the character of the attack, the — sudden disappearance of the aphidids, and the fact that they did not ~ disturb wheat coincide with our observations on this insect in this ~ latitude and to us clearly point to Toxoptera as the originator of the trouble. Part of the trouble referred to in letters cited in Bulletin 210 of the Ohio Agricultural Experiment Station was, in all probability, due to © ‘‘oreen-bug’’ attack, since from our own observations on this species — in northern latitudes a part of this injury appears to be characteristic of Toxoptera. North and South Carolina also suffered somewhat from the depre- dations of this insect in 1907. The senior author made a trip into this section, reaching Sumter, 8. C., April 17, 1907. He found that all fields of oats, the only grain sown, were more or less affected; here and there brown areas occurred, showing the characteristic work of Toxoptera. This condition was noticeable from Sumter, S. C., to Charlotte, N. C., indicating that the infestation was general. Both Macrosvphum granarva Buckt. and Tozoptera graminum Rond. were — present, but the latter was by far the more numerous. There were ~ very few parasites or coccinellids in evidence. In a letter dated June 18 Mr. E. C. Haynsworth, of Sumter, stated that soon after the ~ senior author’s visit in April the eee became warmer and Toxop- — tera disappeared very rapidly. In some parts of North Carolina the injury was itn serious. Mr. Franklin Sherman, jr., of the North Carolina Department of Agricul- — ture, has kindly placed his notes on this outbreak at our disposal. — He stated that the worst area of infestation centered about Winston- Salem, in Forsyth County, N. C., although some injury was also inflicted in Guilford, Davie, and Rowan counties in the same State, — some fields being almost totally destroyed. Parasites were present, though not in sufficient numbers to hold Toxoptera in check. The senior author went directly from Sumter, S. C., to Winston- Salem, N. C., reaching the latter place April 19, where he was met by ~ Mr. Sherman, and they went over the ground together. A number ~ of fields were examined, ranging from slightly infested to totally — destroyed. Insome fields of wheat, where there had been quantities — of volunteer oats, the infestation was more severe. Parasites were — present in great abundance in some fields, but they did not appear to have checked the pest ia time to save all of the fields. The senior author thus summarizes this outbreak: From a study of the entire neighborhood it seems quite evident that the outbreak of Toxoptera in the vicinity of Winston-Salem was primarily due to the presence of Bul. 110, Bureau of Entomology. U. S. Dept. of Agriculture. PLATE lI. Fig. 1.—STAND ON WHICH REARING EXPERIMENTS WERE CARRIED OUT IN REARING THE SPRING GRAIN-APHIS. (ORIGINAL.) Fia. 2.—AREA ON GROUNDS OF THE UNITED STATES DEPARTMENT OF AGRICULTURE, AT WASHINGTON, D. C., WHERE THE SPRING GRAIN-APHIS USUALLY OCCURS ON BLUEGRASS IN EXCESSIVE ABUNDANCE DURING SUMMER. The area infested is indicated by a+. (Original.) THE OUTBREAK OF 1907. a7 fields of fall oats and more or less volunteer grain in other fields, all of which consti- tuted breeding grounds for the pest during the preceding autumn, and from which winged individuals migrated and established new colonies in other fields; these, owing to influence of weather on the development of parasites, caused the most of the injury in wheat. We received a letter with specimens from Mr. L. M. Smith, Mr. Sherman’s assistant, at Newport, Carteret County, N. C., stating that he found a small field of oats in the outskirts of town that was’con- siderably damaged by Toxoptera. This county is on the coast and Newport has an elevation of 19 feet. From this it seems that in all probability Toxoptera covered the entire State. The senior author also found Toxoptera in destructive abundance at Midlothian, Chesterfield County, Va., in a small meadow of orchard grass. Mr. J. L. Phillips, the State entomologist, reported a slight outbreak at Cloverdale, Botetourt County, Va., in rye, and stated that considerable damage had been done in some parts of the field. One undetermined Aphidius was found at Midlothian, while none was reported from Cloverdale. There was an outbreak of Toxoptera in the bluegrass lawns north of the buildings of the Department of Agriculture at Washington, D. C.,in July, 1907. The infested area (see Pl. II, fig. 2) was appar- ently confined to the space of about an acre, where it was excessively abundant; outside of this area practically no Toxoptera could be found. This offered a good opportunity to test spray materials and a number of experiments of this kind were carried on. Dr. Howard, personally, found Aphidius present in this infested area though in very limited numbers. In all probability this was Aphidius avenaphis Fitch, as we have since found this species in this exact locality but at no time have we found A. testaceipes Cress., which, until Mr. Viereck revised this group, had been considered to be Lysiphlebus tritict Ashm. We did not, in 1907, find any species of Aphidius present and did not know that Dr. Howard had done so, as he soon after sailed for Europe and at the time Circular 93 of this bureau was published the statement as to its nonoccurrence was not called to his attention in time to be corrected and he did not inform us of his find, supposing that we knew of it already. Mr. Kelly, how- ever, found Allotria sp. present there in 1907, and we have since found this to be a parasite of Aphidius, which may account for the fact that the latter was present in such limited numbers. In 1908 Aphidius avenaphis was quite plentiful there, although specimens were not preserved, while Allotria sp. was found sparingly on the grounds else- where in the vicinity. As Toxoptera attracted no attention in this area on the grounds of the Department of Agriculture in 1909 we have no records for that year. In 1910 Toxoptera was again injuri- ously abundant on the same area and no Aphidius could be found, while Allotria sp. was still in evidence. It seems possible that condi- 1 7 f fi oe — —.) ee 38 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ tions were unfavorable for the rapid increase of Allotria in 1908, which conditions would prove favorable for Aphidius and also unfavorable for its host, the Toxoptera. This infested area on the department grounds in Washington has proved to be of considerable interest, as the fluctuations of Toxoptera there, as well as those of its parasite Aphidius and the secondary parasite Allotria, must coincide with what is going on in similar places over the country, thus forming small secluded breeding areas where Toxoptera survives throughout the summer, more especially in the South. The area in question is a depression covered chiefly by bluegrass, occupying perhaps half an acre, surrounded on all sides except the south by shade trees (See Pl. I, fig. 2.) Itis rather more moist and therefore cooler in summer than other portions of the grounds and in common with the rest is kept closely mown. An underground steam pipe which affords heat for a large number of greenhouses extends along the southern and eastern margins; the ground above this pipe is always much warmer than the surrounding area during winter, the snow disappearing first and the grass in that location starting much earlier in spring. So far we have not found that these latter conditions have any influence in enabling the Toxoptera to breed viviparously during the winter. Even when the Toxoptera was excessively abundant here none could be found in the bluegrass-covered grounds only a few yards away, except in 1910, when it was quite numerous about the Washington Monument some four blocks away. Because of its isolation—there are no grain fields within miles on the Maryland side of the Potomac River and the department experiment farm at Arlington, Va., has the only grain for miles on the west side of the river—and because these last had never suffered from Toxoptera attack, this area became of too much importance as a convenient field of observation and experi- mentation to make an attempt at experimenting with the importation of great numbers of Aphidius desirable. There is every reason for believing that it is in similar favorable localities that Toxoptera _ passes the summer months in the southwestern portion of the country, where, as observations have shown, it is not able to withstand the high temperatures of the open fields. Toxoptera has been studied throughout the summer in the South- — west with much difficulty, and not at all satisfactorily for the reason that we have been unable to keep it under continuous observation in — the open fields. Except in cases of local outbreaks here and there over the country there has been no serious injury to grain crops by the “‘green bug” since 1907. Many additional localities for the species have been added since then, however, and it now appears to cover almost the entire United States, excepting perhaps New York and the New England States. (See fig. 4, p. 19.) THE OUTBREAK OF 1907. 39 LOSSES FROM DEPREDATIONS IN 1907. It is impossible to arrive at the actual monetary loss occasioned by this fearful outbreak, as no data have been collected with this special end in view, either by the State or National governments. Several points must be considered in making such an estimate. Large areas planted to wheat and oats were abandoned, part being planted to other crops and the remainder left lying idle. Much money that was entirely lost was expended in seed, fertilizers, pre- paring the seed bed and planting; of course all of the fertilizer would not be lost where another crop followed. The greatest source of loss came through partial or actual destruction of the young wheat, thus greatly reducing the yield. The Bureau of Statistics of the Department of Agriculture kindly compiled the following table for us, which will shed some light on the amount of loss probably attributable to the ‘‘green bug.” TABLE I.—Losses from depredations by the spring grain-aphis in 1907 in Kansas, Oklahoma, and Texas. KANSAS. Winter wheat. Oats. Acreage planted Per . : in fallof | cent ea eee Total pro-| 4 creage ae Total pro- me es spew (revised). | acre. duction. acre, | duction. liminary). Bush. Bushels. Bush. Bushels. Rae ek 5,645,000 | 6.3 | 5,290,000] 13.9 | 73,527,000 | 858,000] 27.1 | 23,248, 000 TG ea 5, 702, 000 10.0 5, 132, 000 15.3 | 78,517,000 1, 050, 000 23.6 24, 780, 000 WOWeo se e.-----2' 9,930; 000 4.8 5, 645, 000 11.3 | 63,788, 090 1,092, 000 15.0 16, 380, 000 TOR SSeS ee 5, 930, 000 205 6, 108, 000 12.8 | 78, 182,000 994, 000 22.0 21, 868, 000 1 Aye ee a 6, 173, 000 any 5, 895, 000 14.5 | 85, 478,000 964, 000 28. 2 27, 185, 000 CRG oe Se ee 6, 195, 000 35.0 4,300,000 14.2 | 61,060, 000 1, 400, 000 33.3 46, 620, 000 oo) ae eae re See 73,425,000 |............|........] 26,680, 000 OKLAHOMA. 1905: 4 ee ee 286, 000 5.5 270, 000 10.0 2,703, 000 202, 000 36.0 7, 258, 000 (C1 ae pe ae 1, 493, 000 3.9 1, 435, 000 8.2 | 11, 764, 900 294, 000 33.0 9, 717,000 1906: ves 2495, 000 3a 241, 000 12.0 2, 890, 000 218, 000 34.2 7, 447, 000 WIG Sess: 1, 403, 000 5.0 1,333,000 14.0 | 18,664, 000 350, 0CO 34.4 12, 040, 000 1907: j Ind. T..._... Sie Ontos. eh < eee A Way oS EIU. Ordae eo. o 1, 235, 000 35.0 959, 000 9.0 8, 631, 000 418, 900 15.0 6, 270. 000 LEDS 0 ie 1,379, 009 Dos 1,347, 000 11.6 | 15,625, 000 450, 000 25.0 11, 250, 000 LUO ee eee 1,241, 000 6.5 1, 225, 000 12.8 | 15,680, 000 550, 000 29.0 15, 950, 000 LSI ee ee 1, 604, 000 3.0 1, 556, 000 16.3 | 25,363,000 632, 000 36.5 23, 068, 000 PRUE ARCS ee ese alee eyo ils tee. cer elo. 2 = Sek IGS 887000" pase oo ee eee 15, 500, 000 TEXAS IN 1,319, 000 ORG: 1, 249.000 8.9 | 11, 118, 000 914, 000 31.4 28,713, 000 ees 1, 266, 000 3.0 1, 228, 000 11.5 | 14, 126,000 914,009 34.8 31, 823, 000 LS aT Se eee ae 1, 266, 000 70.9 380, 000 7.4 2,812,000 500, 000 19.0 9, 000, 000 LN er 988, 6.5 924, 000 11.0 | 10, 164, 000 750, 000 28.9 21,675, 000 LSS ae 929, 000 PA (eats) 555, 000 9.1 5,050, 000 615, 000 18.7 11, 500, 000 Bers ee 1, 295, 0CO 3.3 1, 252, 009 15.0 | 18,780,000 695, 000 35.0 24, 325, _. 2. = * 40 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ If we average the 5-year period and calculate the loss on this basis for 1907, it will be seen that the total crop for Kansas, Oklahoma, and Texas fell about 50,000,000 bushels short of this average—both wheat and oats being considered. Seventy per cent of the Texas wheat acreage was abandoned. This does not represent the loss as it actually occurred in various — parts of the States, as some parts of each State were more badly ~ affected than others and the good parts would bring up the yield for the poorer portions. Sumner County, Kans., is a good illustration of this. It is located in the extreme ee portion of the State and was in the badly infested districts. To quote from a letter from Mr. George H. Hunter, of Wellington, Kans., dated February 6, 1908: I wish to explain that our crop of winter wheat in Sumner County for the year 1907 amounted to 1,909,574 bushels; this is our latest estimate, while the general average is about four and one-half million bushels for Sumner County, and that would be a safe basis for you to figure on. According to our acreage last year, if it had not been for the green bugs, I think we would have had at least four to four and one-half million bushels of wheat. THE SITUATION IN 1911. The winter and spring of 1910-11 west of the Mississippi River, but not east of it, was such as would tend to bring about another invasion from the pest. Some injury was reported, accompanied by specimens, from Pecos River valley in southeastern New Mexico. Mr. J. T. Monell of this bureau, however, visited the locality in April and reported the pest as having disappeared without doing serious injury. The material received was almost universally para- sitized by Aphidius testaceipes Cress., which probably overcame the Toxoptera before its occurrence reached the magnitude of an invasion. There was also a limited incipient outbreak in eastern Oklahoma, which was investigated by Mr. Kelly. Here, too, the parasites apparently gained supremacy before serious injury was done, except perhaps in a few isolated cases. There is little doubt that the unusual and excessively high tempera- ture for even a mild winter that prevailed throughout the Southwest during a portion of the winter months was sufficient to revive the parasites as well as to aid their host, and thus bring about conditions that enabled the parasites to prevent the aphidids from increasing in numbers to a point where they were beyond their control. THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”? 41 FOOD PLANTS. This insect has a very wide range of host plants and can on that account find fresh food at any season of the year. In this way it is enabled to perpetuate itself over vast areas of country and under almost every variety of climate. Rondani, who first described the species in 1852, gives the following list of host plants: Oats (Avena sativa); wheat (Triticum vulgare); spelt (Triticum spelta); Arrhenatherum elatius (Avena elatior); couch grass (Triticum repens); Hordeum murinum; Lolium perenne; Capri- ola (Cynodon) dactylon; soft chess (Bromus hordeaceus) (mollis); and corn (Zea mays). He states also that Toxoptera had been found quite abundant upon the foliage of rice (Oryza sativa) and common barley (Hordeum vulgare). We find no other references to its being found upon rice. In 1863 Passerini adds sorghum (Andropogon sp.) and he also observed it on barley. Macchiati, in 1882, added the following hosts: Dactylis glomerata, Bromus erectus, and B. villosus (maximus); in 1883 he added Triticum villosum, Avena fatua, and A. barbata; in 1885, Poa annua. Del Guercio, in 1906, mentions it as occurring upon buckwheat (Fagopyrum esculentum). This is the first and only reference we have found in which it has been accused of infesting plants other than those belonging to the Graminee. Toxoptera was first observed upon wheat and oats in the United States. In 1889 the senior author observed it feeding upon rye and in 1890 he found it plentiful at Lafayette, Ind., upon Dactylis glomerata. In 1907 he found it destructively abundant upon the same grass at Midlothian, Va. This infested field was from 4 to 5 miles from wheat, oats, or rye fields. In Insect Life; he states that Toxoptera will live upon the leaves of all kinds of grains, including corn, during summer. In 1902 he found Toxoptera feeding upon cheat (Bromus secalinus) and rye grass (Elymus canadensis) at Peotone, Ll. The junior author found it quite abundant on volunteer corn plants among oats on April 2, 1907, at Hobart, Okla. A cornfield near a badly infested wheat field was found to be suffering also. Mr. C. N. Ainslie of this bureau, on April 4 of the same year, at Kingfisher, Okla., found a cornfield that was seriously injured by Toxoptera. Farmers in Oklahoma were very much disturbed over the prospect that the corn also would be swept away by the “‘green bug,”’ but later developments proved that it was not a serious pest to corn. The _ junior author found Hordeum pusillum and Alopecurus geniculatus badly infested on April 12 at Kingfisher, Okla., and Agropyron occiden- tale was found harboring the pest in large numbers at Hooker, Okla., in May. The senior author, Mr. Ainslie, and Prof. E. A. Popenoe, 1Insect life, Div. Ent., U. S. Dept. Agr., vol. 4, p. 245. 49 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’’ of Kansas, also found the Hordeum pusillum much infested later in the season. In July there was an outbreak of Toxoptera on blue- grass (Poa pratensis) on the grounds of the United States Department of Agriculture, Washington, D. C. Later in the season the junior author found it on bluegrass in the fields about Richmond, Ind. In the fall of the same year (1907) this was the only plant on which the sexes and eggs could be found. In fact, for Indiana, Illinois, Ohio, and more northern localities bluegrass appears to be the normal host, and the ‘“‘green bug”’ is readily found upon it at any time in the year even when it can be found only sparingly upon any other plant. A number of new host plants were added to the list in 1908. Mr. Kelly, of this Bureau, found Toxoptera feeding freely in the fields upon Hordeum jubatum and Distichlis spicata in Montana and upon a species of Andropogon in Colorado. Mr. Ainslie found it breeding freely in the fields upon Hordeum jubatum, H. cespitosum, H. nodosum, Elymus striatus, Agropyron tenerum, Bromus unioloides, B. porter, Stipa vridula, and Polypogon monspeliensis about Artesia, N. Mex. In one instance Mr. Ainslie found several alfalfa plants (Medicago sativa) with colonies of Toxoptera upon them, as many as 21 speci- mens being observed on a single leaf. This seems very unusual and we have no other records of its occurrence on this plant. Prof. C. P. Gillette, of Fort Collins, Colo., found it infesting Agropyron occidentale, and in 1907 he found it feeding upon bluegrass. During the summer of 1908 Toxoptera was found by the junior author to breed freely upon Dactylis glomerata, Eleusine vndica, Eragrostis pilosa, EL. megas- tachya, Sporobolus neglectus, Agropyron repens, Elymus virginicus, E. canadensis, and Bromus secalinus, in his rearing cages at Rich- mond, Ind. : In 1909 and 1910 a few more plants were added to the list. Mr. Ainslie found it breeding freely upon Hordeum murinum in Arizona and upon Agropyron occidentale in New Mexico. Mr. Kelly found it breeding freely upon millet (Chetocloa italica) and upon Japanese millet (Hchinochloa crus-galli) in Kansas. Mr. Harper Dean, jr., then of this bureau, found it feeding upon Stipa leucotricha in Texas. Mr. T. D. Urbahns, of this bureau, found that it bred readily in his cages at Dallas, Tex., upon Bermuda grass (Capriola dactylon), Chetochloa viridis, Johnson grass (Sorghum halepense), and upon rice (Oryza sativa). During the summer of 1909 Mr. T. H. Parks, of this bureau, and the junior author observed that Toxoptera bred freely upon Elymus striatus, Juncus tenuis, Poa compressa, Bromus commutatus, B. tec- torum (%), B. wmermis, sheep’s fescue (Festuca ovina), hard fescue (F. duriuscula), meadow fescue (Ff. elatior), various-leaved fescue os FOOD PLANTS. 43 (F. heterophylla), F. rubra, Agropyron occidentale, and Italian rye grass (Lolium multiflorum), in their rearing cages at Lafayette, Ind. The following is a complete tabulated list of host plants* to date, in so far as our records show. IN EUROPE. Barley. Bromus erectus. Corn. Bromus maximus=B. villosus. + Oats. Bromus mollis=B. hordeaceus. Rice. Capriola (Cynodon) dactylon. Wheat. Dactylis glomerata. Spelt. Fagopyrum esculentum. Sorghum. Hordeum murinum. Agropyron (Triticum) repens. Avena barbata. Avena elatior=Arrhenatherum elatius. Avena fatua. Alfalfa (Medicago sativa). Agropyron occidentale.” Agropyron repens. Agropyron tenerum.” Alopecurus geniculatus.? Cheat (Bromus secalinus).? Bromus commutatus.? Bromus inermis.” Bromus porteri.” Bromus tectorum (?).? Bromus unioloides.2 + Capriola dactylon. Chxtochloa italica. Chetochloa viridis.” Dactylis glomerata. Distichlis spicata.” Echinochloa crus-galli.? Lolwum perenne. Poa annua. Triticum villosum. IN AMERICA. Eleusine indica.” Elymus canadensis.” Elymus striatus.” Elymus virginicus.” Eragrostis megastachya.” Eragrostis pilosa.” Festuca duriuscula.” Festuca heterophylla.” Festuca ovina.” Festuca elatior. Festuca rubra.” Holcus halpensis.? Hordeum cxspitosum.? Hordeum jubatum.? Hordeum murinum. Hordeum nodosum.’ Hordeum pusillum.? Juncus tunuis.” Lolium multiflorum.? Poa compressa.” Poa pratensis.” Polypogon mons peliensis.” Sporobolus neglectus.” Stipa leucotricha.? Stipa viridula.” 1 During 1909 Mr. C. P. v. d. Merwl, Bloomfontein, Orange Free State, Africa, wrote us that he had found Toxoptera graminum attacking ‘‘ Bermuda grass”’ and their native blue-grass (Andropogon hirtus). 2 These are host plants not previously recorded. 44 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ CHARACTER OF ATTACK. The actual effect upon the plant, whether chemical or physiological, is not clearly understood. If afew Toxoptera be placed upon a per- fectly healthy plant, in a few days the tissue in the immediate vicinity of the aphidids will take on a yellowish tinge; if the aphidids remain in one place for a considerable time and increase in numbers, the whole plant gradually turns yellow and dies, the leaves changing to reddish brown. When the original source of infestation arises from some one or more points within a field, as described elsewhere in this paper, the plants take on a yellowish color in small, almost circular areas, (Pl. I, fig. 2) and as the Toxoptera increase in numbers the plants in the center die, becoming reddish brown, and the aphidids work outward in every direction from the center, gradually enlarging the spot until it may cover many acres. When a field is infested from without by migrating forms, the aphidids appear to spread evenly over the entire field and the whole gradually turns yellow, and in cases of severe outbreaks a whole field may die simultaneously. (See Pl. I, fig. 1.) These aphidids are essentially leaf-feeders, rarely if ever being found injuring the heads or fruiting parts of the plant. Toxoptera appears to have a more strikingly disastrous effect upon wheat or oats plants than any of the other common grain aphidids. Seemingly when in no greater numbers than other species the plants will succumb more quickly to the attack of Toxoptera. VIVIPAROUS DEVELOPMENT. Tozoptera graminum, as already shown, has been found to breed over a wide range of country, and its behavior, under the varying temperatures and climatic conditions prevailing over this vast terri- tory, presents and opens up a broad field for investigation. IN THE SOUTH. In northern Jatitudes the normal manner of reproduction among the Aphidide is both sexually and asexually. In southern latitudes hese conditions, apparently, do not obtain, as here the normal means of reproduction seems to be asexually, each generation being com- posed entirely of viviparous females. South of about the thirty-fifth parallel, except in high altitudes, it appears that Toxoptera breeds continuously throughout the year without the appearance of the true sexes. April 6, 1906, Mr. George I. Reeves, of this bureau, found the eggs of a plant-louse on wheat at Nashville, Tenn., and Mr. Kelly found males (fig. 6), females, and eggs of Toxoptera at Knoxville, Tenn., in December, 1908. The eggs found by Mr. Reeves may have been those of Toxoptera, but we 45 VIVIPAROUS DEVELOPMENT IN SOUTH. a Biot Bite es dal tn) fis the COSCO SOP SCI - 7s » Bh Ni Ue ft Ne ea ic ii as Ba) Th i rh, nk Colt Wasav i Ko @ PN (‘TeutsI0 ) “UU G T ‘OzIs Tenjoe ‘posiepuny ‘J 0 —— *eUTIOJUB PuB oR :(wnuruoL6 DLagdoxo,y ) s1yde-uyei3 Buyids oy.— D2 9 “SIT SNe @n . See, on arate ae - Oy reg PRET 140% Lu we cediry ‘i © pe gs Ba OQ)" edi (no OC ind i & a cea a= THE SPRING GRAIN-APHIS OR ‘‘' GREEN BUG.’’ 46 » Tae Oa ZR se 4 F a VIVIPAROUS DEVELOPMENT IN SOUTH. © 47 can not be sure of the species as they were not reared. Winged and wingless viviparous females (figs. 7, 8) were, however, present at the time the eggs were found, as were also those of both Aphis (Sipho- coryne’) and Macrosiphum. Mr. E. Dwight Sanderson obtained the males and oviparous females of Macrosiphum granaria Buckt. in Texas but only artificially in his rearing cages. Mr. R. A. Vickery, of this bureau, found males, females, and eggs of Aphis maidi-radicis Forbes at Salisbury, N. C. These instances mentioned above are probably the most southerly points at which oviparous forms of plant-lice have so far been found in the United States. In the Southern States, wherever there is sufficient food, Toxoptera SS eecatly breeds vViviparously V throughout the / year; for this rea- ” son the number of / generations here, other things being equal, should far exceed that in the Northern States. As a matter of fact, however, the dry, hot, protracted summers of the So uthwest are Fig. 8.—The spring grain-aphis: Wingless viviparous female. Enlarged; actual size, 2mm. (Original.) probably disas- trous to the species during the hot months, except perhaps in secluded nooks, where there is a supply of een host plants. In northern Texas, as observed by Mr. Urbahns, during June of 1909, Toxoptera rapidly disappeared with the ripening of the grain crops and the approach of hot weather. Winged forms migrated with the breeze early in this month, and wingless forms soon perished from extreme heat and a shortage of green food in the field. Obser- vations clearly showed that it was almost impossible for the ‘‘green bug” to live and reproduce in grain fields during the summer. While 1 Probably Siphocoryne avenze Fab. The use of the generic name Siphocoryne, as applied to this species, is questionable, and is not at present followed by many, perhaps the major portion, of the students of the ) Aphidide. According to Schouteden (Ent. Soc. Belgique, vol. 12, p. 217, 1906, Catalogue Aphides de Belgique) it should be Aphis. Some of our best students, however, admit that this particular species, avenz, is on the borderland between Siphocoryne and Aphis. - *S _ 4 48 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ the temperature was above and precipitation below normal, during this particular season, the effect was so evident that there is reason to believe that under normal conditions these aphidids do not live in fields directly exposed to the sun during the summer months. The table on pages 64-69 on daily reproduction, length of reproductive period, and longevity show a decided decrease in all of these for the summer months over those of spring and fall. The facts upon which these figures were based could be secured only by pro- tecting the aphidids from exposure to the hot summersun. Aphidids exposed without such protection were unable to live through the season, though special care was taken to furnish them with a supply of green food plants. Mr. Urbahns secured the following results by removing Toxoptera, together with its green food plants, from a shaded position and sub- jecting it to the temperature of loose, unshaded soil. August 18, with the soil temperature at 145° F. in the sun, 12 Toxoptera on a wheat plant were exposed 30 seconds; 5 fell to the ground dead, 7 remained on the plant dead. Three adults and 4 young on a wheat plant were similarly exposed for 30 seconds, after which time all were dead. One winged and 4 wingless adults on a wheat leaf were exposed for 30 seconds, when they were found to be dead on the plant. Thirteen adult aphidids on wheat plants were exposed for 15 seconds, 5 fell to the ground dead. After 30 seconds exposure the plant wasremoved to the shade; 6 more were then dead on the plant and 2 were alive between the leaves. Soil temperature 118° F. (shaded by cloud). Nine aphidids on a wheat plant were exposed for 30 seconds, 2 died, and 7 remained alive. A potted wheat plant bearing several hundred aphidids, the temperature being 114° F. in the shade, was removed from the shade for 5 minutes. A large percentage of the aphidids fell to the ground, some survived, but many died. A potted wheat plant bearing several hundred aphidids was kept in the shade where the maximum temperature was 114° F. Next morning many of the aphidids were dead. When the soil temperature was 116° F. shaded by a thin cloud, 3 aphidids on a plant were exposed for 60 seconds, 1 died, and 2 remained alive. August 19, the soil temperature being 128° F. in the sun, 12 aphidids on a young plant were exposed for 30 seconds; 5 fell from the plant and died, while the other 7 were dead on the plant. When the soil temperature was 130° F. in the sun 12 aphidids on a young plant were exposed for 20 seconds. All were then dead. When the soil temperature was 128° F. in the sun 11 aphidids ona plant were exposed for 30 seconds; at the end of this time all were dead—4 fell to the ground, and 7 remained on plant. At a soil temperature of 130° F. in the sun 8 aphidids on a plant were exposed for 15 seconds; all were then dead—3 fell to the ground, and 5 remained on the plant. The results of these experiments prove that Toxoptera can not survive the summer in the open fields in sections of the country © where the pest commits its most serious ravages with the greatest 1Mr. J. T. Monell suggests that this may be due as much or more to the hot, dry air as to the direct rays of the sun, a eS ee ee a ~~ eee ee : . . . { g frequency. They also account for our inability to locate it in such territory during the summer months. A careful search was made at different times for grasses that were actually serving as summer food plants. The only hope of finding such was in well shaded spots along streams, where, from all indications, Toxoptera would be sufficiently protected to live and reproduce throughout the summer. At Plano, Tex., Toxoptera was rapidly disappearing from the fields in early June. By June 14 there was only a limited number of plants which still supported the remaining few of these aphidids and the latter were soon carried away by ants. When confined on green food plants and protected from their enemies by a large frame covered with thin cheesecloth Toxoptera lived until July 3. After this date it was apparently too hot for their existence. Out in the VIVIPAROUS DEVELOPMENT IN NORTH. 49 open, where young wheat and oats plants were sustained by frequent _ watering, they lived until July 15. After this date they apparently could not endure the summer temperature and no more were found. Since no reinfestation appeared up to November 30, it was quite evident that the aphidids had all perished. On June 28 viviparous forms of this species were found rather abundantly in a small field of oats at McAlester, Okla. This field of a few acres in size was on the east slope of a rocky hill. A natural growth of timber surrounded the field and a few trees grew in its midst where rocks make cultivation impossible. Green vegetation was abundant in shaded places and along the creek one-half mile to theeast. Conditions of this sort are certainly favorable for Toxoptera to live and reproduce throughout the summer as long as they find the food plants present. While these spots, favorable to Toxoptera, are characteristic of eastern Oklahoma, where, as has been stated, an incipient outbreak of the pest actually occurred in 1911, they are also found along streams in the central part of that State and in northern Texas. As there appears to be no resting or egg stage in the South, whenever there is a warm open winter these’ aphidids become very abundant and threaten the grain crops of this region. IN THE NORTH. Farther north, in the vicinity of Lafayette, Ind., viviparous repro- - duction is confined to the months of April, May, June, July, August, September, October, and November. During mild winters, how- ever, the species may breed viviparously throughout the year, as the _ senior author found it breeding in the open throughout January, Feb- _ ruary, and March, 1890, notwithstanding the fact that on January 24 _ the temperature fell as low as + 3° F.; on February 9, to + 6°F., _ and on March 6 to + 4° F. It appears that a temperature of about | 26675°—Bull. 110—12—4 50 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ zero, with no protection, is fatal to Toxoptera, except to the egg, but the fact that it withstood the winter in 1890 can easily be accounted for. That winter was unusually mild throughout, with the excep- tion of the dates mentioned, and if one consults the weather records it Fic. 9.—The spring grain-aphis: Oviparous female, showing eggs within the abdomen. Enlarged; actual size, 2.25mm. (Original.) will be found that on January 24 there were 3.5 inches of snow, Feb- ruary 9, 3.4 inches, and March 6, 4 inches. The covering of snow in each instance would appear to have been sufficient to protect the Toxoptera, as on December 8, 9, and 10, 1909, at Lafayette, Ind., the temperature fell as low as from —1° F. to ~4° I’. below zero, and plant-lice of all kinds, in the rearing cages out of doors, were killed, while those in a near-by wheat Fig. 10.—The spring grain-aphis: Hind tibia of oviparous field, covered with several female. Greatly enlarged. (Original.) inches of sn ow, were found to be in good condition on December 13, at which time the cold spell was broken and the ground began to uae. As a rule, Toxoptera breeds slowly 1 in October and November, at which time the majority become oviparous females (figs. 9, 10) and males (fig. 6). pots were placed on a rearing stand were secured. THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ 51 REARING METHODS. All of the rearing work, unless otherwise stated in the text, was conducted out of doors under as nearly normal conditions as it was possible for us to secure. The wheat plants on which the Toxop- tera were confined were grown in flowerpots and covered with lantern globes, over the top of which was drawn a very thin fabric commercially known as swiss. The having one side hinged in such a manner that it could be let down in fair weather and closed up in case of gales or severe beating storms. This stand with its contents is illustrated in Plate IJ, figure1. A thermograph was placed in this stand, and thus continuous records of temperature In the middle of the summer of 1907 two series of investigations were begun and were continued until De- cember to determine the number of generations. In both 1908 and 1909 series of generation studies were begun in spring with the egg (fig. 11) and continued until the egg-laying forms appeared in the fall. In making these observations, the first individuals to hatch from the eggs in the spring were isolated; the first-born from these were in turn isolated, and this process was continued throughout the Jak season until the egg-laying forms ap- Fig. 11.—The spring grain-aphis: Eggs as peared. The last-born was also kept deposited on leaf: a, Dorsal view; b, lat- and the same mode of procedure con- ie tne wad) ee tinued until fall, as was the case in the line of the first-born. All young other than the first-born of the first series and the last-born of the second series were counted each day and destroyed. In this manner, each series being considered, we would arrive at the maxi- mum and minimum number of generations. During these three years a vast amount of data, besides that on the number of generations, was thus accumulated. 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ARs ESS ee eee IIR ae ee vale epee ee gees = [ear eee sie cee ee el ese ec H lat OB Aaa Sa isa Reb | | ahaa CUS 0 Pa Lah Bi a ir aa (aaa eee a to ete ee ea Sees eee ee es eee ee ed Gee ee Oe 0 0 ee aaa meseclecwtec|eecees|wece wales elsas aslo e selec w melon eefececcloweernlsccceelsecvccl|eneves Lgl ee aaa ae CO ei seme aera da SAO al apa el sl ikl co a) Re | SS a RA EES Se |e cer ate |eceeclee eel te ate = = Ieee = tere peers bec fete el bere woe tl rll ea cove[esee[eee-[eeeee[eseee[eeeeeleeess Gea er lees ce lees cea eee «ele ee eelw eece enterel ea eeartabeeeel ed borarel care el peters ea col Pee Sa |e, se | Noir Ge Meg tle ec = TEs I Seat Rees ee cl eater erate enter ete org etl rel el Sarre pcos mone eee ele eo see ce oe Oe NOC cO) < leae TIE es Wee alee [pee ele alae ee eos epg poor ioe gel eames cae a ng oe ms (ese |i See ali seapasecale reali cline liye We (REE = aleea dl Mane ‘ Bae ale Mee cth te |pen -- eseelbrew wellesnce eh errelh x tordlitevtvellc Banc haan ese dusewe padre fdlh «led Paes ay 2 ltt clases cleee cllmree ; hil Bs i SR | Rg: nt | epee |e | I Peet Fe Be aay | ee | Ee ee Gee ee ee es Oe 0 I | ee ss ee i be SIP Veal bs Sis Anca wok dale ¢evaieee ropes a8 Belg eg ese so liteee olecren cle Boate ll ecg bss ara ait nal ol pred a nal iiate ete ae al arte Piece car teases face cles asleee Grete IOs loa 2s Re Se A See Sons ees ess ee ee ge es See = pee ee ean a Sees eee ee ed ee ee 0 € I Cs dO ee ed ee ee pies Shee a Meche an culieee s\Seaealewws Oo et Ng. hares eee cecal aeeelirawe dle sev allereecdae ena |teaeelmretelewars|beenalam an ae cealmaoel Brea es ee ee Ge ee es ee eee ee 0 Ags dlc eallec ore eens Sees cals sec eg lea ete Sole Beeler lec Mle aad EG oi ee eel ee las le dig aes are Ee ee ee ee, Tl TA) oe) | | Poe Blog AJ oa iy] 09 Ed] 0g Plog Mi og log log losin] 4 Bi ml mw] SS] 6B] CUR >| oS) kl elas cE oS ga S4 gz dal § a Cr Gn.1 So cals §-l|og ee ott oslok EleSliekles sh BERG EE SE/88/28/S8|eo/Se/S2/88le4/er|shlekles|so|s5/s5|/82|s8|s5/25/88 gezles| 22 . 5 |= ct =e ct ct =¥ Saeaiseler S| Se/ So) Se ee RS) Se ee ec es eee jes SPE SRI SSS | og SEE | 2a) Sis Bol BP BPR | Bal BRIS hl SR SB /SR/58/58/ 55/58/55) Sr) 55) Fy | Fe | Be | ba | Be 8 | Bog | Bog | Bog | OS ee ee ee ee ee eee Ree ee eee ee a A ee ‘SoLI0S UOT}VIOUNS T10G-4SI1T ze 6S gg | 89 og | 99 OP | GL cy | 62 Le | LL Ly | GL or | #8 6€ | 18 Gy | 8L 9F | 62 88 | #2 96 | &Z GZ | 69 68 | Tg ch | So Z& | 09 Tr | 09 4 a 6& | &8 ve | 98 4@ | 62 L4@ | 69 co | 2S rE | 29 8 | bl ve | SS wr | 92 vg | 48 Lg | 06 TS | 2 ecg | &6 €¢o | 06 Tg | 16 TS | 96 0S | 96 ain} ered ua J, ‘0 *(06T) eyed ‘ponurju0j—'‘puy ‘puowyny ‘“so6r ‘Le lope 66a ay) wolf payoqny yoy} JONPILIpUL UD WOLL Salas UOYWDLIUAD ULOQ 18D] PUD ISLUT Std Yen) REARING METHODS, & ‘snorediaAo 1npy 1 - =~2--|-- eels ee ele eee ele eee ele ee ee wee ele eee Sees ee ee i ee ee eed wen ele eee Pe Oe ee Oe ee ee ey eee ees ee ee ee ee oe ee eee eee eee eee ee Sees eee ees ee or nl ~~ oqooococooccoocooooeoeocoooocrwocmmwcoc ooo ON ConmOonoon | meer elon eee re Ce ee Oe Ur Oe eC ee ee Oe ed ee ie ey ee eee ee ee i ee ee ed e-l--¢ wefeee “AON 58 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ STEM MOTHERS. At both Richmond and La Fayette, Ind., the eggs begin to hatch the latter part of March and continue until about April 10. The first generation, or stem mothers, differs from the next generation slightly in coloration, and there are besides some slight structural differences. The measurements of the body are not included in the following description, as the specimens are mounted in balsam. DESCRIPTION OF THE DIFFERENT INSTARS. First instar.—Before first molt: General color, very dark Nile green; head, beak, antenne, legs, and cornicles very dark gray; tips of the antenne, the tarsi, and the eyes black. Antenne 4-segmented. Measurements of antennal joints (average from 2 specimens): I, 0.034 mm.; II, 0.034 mm.; ITI, 0.093 mm.; IV, base, 0.046 mm.; IV, filament, 0.114 mm.; total length, | 0.321 mm. Second instar.—Before second molt: General coloration of head and body lighter than in the preceding stage, otherwise the coloration the same. Antenne 5-segmented. Measurements of antennal joints (average from 3 specimens): I, 0.045 mm.; II, 0.039 mm.; III, 0.127 mm.; IV, 0.082 mm.; V, base, 0.066 mm.; V, filament, 0.161 mm.; total length, 0.520 mm. Third instar —Before third molt: The color of the body now varies from pale green to deep apple green; head concolorous with body; legs slightly lighter; eyes, tip of beak, tip of cornicles, articulation of femora, and tibiz black; distal two-thirds of antennz black; basal portion greenish gray. Antenne 5-jointed. Measurements of antennal joints (average from 4 specimens): I, 0.050 mm.; II, 0.045 mm.; III, 0.152 mm.; IV, 0.093 mm.; V, base, 0.072 mm.; V, filament, 0.174 mm.; total length, 0.586 mm. ‘ Fourth instar.—Before fourth molt: General coloration variable, though about the same as in third instar, with the exception that the eyes of the young begin to show through the body wall; eyes and tip of beak black; legs greenish gray, the articulation of femora and tibize and the distal portion of tibize very dark, and tarsi black; cauda lighter than the body, as is sometimes also the head; the two distal segments and distal portion of third segment of antenne black, gradually shading off until at the base they are concolorous with the head; cornicles black at tips, shading off into pale grayish green at base. Antennze 5-jointed; sometimes, however, there are 6 distinct joints. Measurements of antennal joints (average from 4 specimens): I, 0.065 mm.; II, 0.051 mm.; III, 0.194 mm.; IV, 0.119 mm.; V, base, 0.088 mm.; V, filament, 0.196 mm.; total length, 0.713 mm. | Fifth instar.—In the adult stage the color varies from a clay yellow to greenish yellow and deep apple green; there is no central dorsal stripe; the eyes of the young show through the body walls. In some of the greener specimens the head is slightly lighter and in some of the lighter colored specimens the head is slightly darker than the body; eyes and tip of beak black; legs pale greenish gray, the articulation of femora and tibize and the distal third of tibize quite dark; tarsi black; cauda in yellow specimens with a yellowish tint and in the deep green specimens somewhat grayish, shape and length same as in summer form; cornicles concolorous with body except the distal third, which is black, shape and length same as in summer form; three distal segments of antennz and distal half of fourth black, the basal joints concolorous with the head. Antenne 6-segmented, though two specimens were found in which one antenna of each was only 5-segmented. at= be , DESORIPTION OF SUMMER FORMS. 59 Measurements of antennal joints (average from 16 specimens): I, 0.066 mm.; IT, 0.049 mm.; III, 0.226 mm.; IV, 0.140 mm.; V, 0.152 mm.; VI, base, 0.091 mm.; VI, filament, 0.225 mm.; total length, 0.951mm. They are slightly pruinose in each stage. The material from which these data were taken is mounted on slides and is in the collections of the Bureau of Entomology, bearing Webster number 5151. The first generation, or stem mothers, is always wingless. All of the following gener- ations differ in color, more especially in the first and second instars. The adult stem mothers; so far as we have been able to learn, never have the darker green dorsal stripe. The antennz are shorter throughout the different instars, and in the adult also, than in the summer forms. DESCRIPTION OF THE SUMMER FORMS. First instar (fig. 12).—Before first molt: General color very pale green, the thorax probably the palest; head pale green with a dusky tinge; eyes brownish black; tip of cornicles black, bases dusky; articula- tion of femora and tibiz and distal portion of tibize dusky; tarsi black; two apical segments of antenne ‘46: %—The spring grain-aphis: ae : Young, first instar. Enlarged; black, remaining segments concolorous with head. catia e..0.75 me (Ome Antennz 4-segmented. Measurements of antennal joints (average from 3 specimens): I, 0.032 mm.; II, 0.033 mm.; III, 0.118 mm.; IV, base, 0.049 mm.; IV, filament, 0.154 mm.; total length, 0.386 mm. Second instar (fig. 13).—Before second molt: General color slightly paler now; head not dusky; eyes same as in preceding stage; legs with a more greenish tinge now, other- wise same as in previous stage; the two basal joints and the proximal portion of the third joint of antenne concolorous with head, other portion black. Antennz 5-jointed. Measurements of antennal joints (average from 2 specimens): I, 0.041 mm.; II, 0.035 mm.; ITT, 0.106 mm.; IV, 0.075 mm.; V, base, 0.062 mm.; V, fila- ment, 0.204 mm.; total length, 0.523 mm. Third instar.—Before third molt: Coloration prac- tically same as in second instar; eyes almost black; bases of cornicles paler than abdomen. Antenne 5-jointed. Measurements of antennal joints (average from 2 specimens): I, 0.056 mm.; II, 0.045 mm.; ITI, 0.172 mm.; IV, 0.099 mm.; V, base, 0.076 mm.; V, fila- ment, 0.259 mm.; total length, 0.707 mm. Fourth instar.—Before fourth molt: General color deeper green now, very close to apple green; dorsal stripe apparent in this stage at times, eyes of young showing through body wall at this time, head a shade lighter than body and sometimes seeming to be tinged with yellow; eyes brownish black; beak black at tip; legs more of a yellowish green now, the articulation of femora and tibiz and the distal portion of the tibiz dusky; tarsi black; the two apical segments of antennze black, next much lighter, third slightly dusky, and the two basal segments concolorous with head. Antennz 5-seg- mented, although sometimes they appear to have 6 segments. Measurements of antennal joints (average from 2 specimens): I, 0.060 mm.; II, 0.045 mm.; III, 0.272 mm. IV, 0.120 mm.; V, base, 0.086 mm.; V, filament, 0.282 mm.; total length, 0.865 mm. All of the above stages slightly pruinose. Fig. 13.—The spring grain-aphis: Young, second instar. Enlarged; actual size, 0.922 mm. (Original.) a ba L Py on oO ; e a fe oe : nf 1.4. ss bh 60 THE SPRING GRAIN-APHIS OR “‘GREEN BUG.” = a The followme ts the description of the adult, summer forms, = given by Mr. Pergande:* ‘ Apierous female | fe. Sa Ycagth 13 Baal age ee ‘ nose, the median line darker green, the head and profhorax somewhai paler than the rest of the body. Eyesblack. Antenne black, the two basal joints and more or less of the third joint at base yellowish. Lees yellowish, the tibiz brownish toward fhe apex, tarsi bleck. Tail dusky. The general color of the lerv= and pupe= is bike iat of the apterous female. Wing pads of pupa dusky fo black. Antenne slender and about ome-hali the length of the body. Necianes shehily tapenng, reaching fo oe slichtly beyund the end of the body. Tail dender, sumewhat omsiricted about the middle, and shout two-thirds the lenzih of the nectaries. There is a disiimet fleshy tubercle each sade of the prothorax and similar tubercles along both sides of the abdo- men. Migratory jomalz [ae 7]|—_Ex- Ppanse of wines 3-7 mm_; lencth of body 15-2 mm. Genenl coloration of the abdomen as In the apterous form; head brownkh yellow; ithe eyes brown; anienmnz, thoracic lobes, the posterior margin af the scuiellum, and the stemal phic bleck; the two bal yom of the antennz yellowsh green: les yellow, the femora more og less dusky, the posteriar pair darkest; apexoftibieand the tarsi black; nertaries and ing gradually to dusky of black toward the end; wimgs transparent; costa and subcosta yellow: the stigma somewhat paler, its immer edge and the veims black Third decoidal oe arenes Coen Seo +. an lon al a a =— mink tenes BEN eet temnze slender, reach- female. Ealoreed: acto! se, 135733 mm. (Onemeal) ing nearly to the colle body, the third joimt provided with 3 to 7 sensors. Nectaries, tal, and laferal © tubercles, 2s im the apterous female:. p Besides the sensoria on the third segment of the antennz mentioned — in the above description, there are from 1 to 2 on the fourth, 1 near © the apex of fifth, and several, more or less distinct, on the base of the — . } « .. ss Measurements of antennal joints (sversge fram § specimens): I, 0.082 mm; Ti, 0.169 mm: Il, 03500 mm; IV, 0233 mm; V, 0.215 mm; VI, base, 0.110 mm; VL, filament, 03% mm; total iemcth, 1334 mm To this description we add: Wingless female (fg. 8)—Coloration for this stage varying from a very pale green With a slight tinge of yellow to a deep appleereen. The domal siripe i not always i Baliciim 3a, Div. Ent., U.S. Depi. Agr, p. 16, = MOLTING. 61 present. The size varies greatly in nearly all forms, wingless viviparous females varying from 1.5 mm. to over 2 mm. Measurements of antennal joints (average for 8 specimens): I, 0.069 mm.; II, 0.045 mm.; III, 0.210 mm.; IV, 0.135 mm.; V, 0.140 mm.; VI, base, 0.089 mm. VI, filament, 0.305 mm.; total length, 0.993 mm. Pupe (fig. 14).—Measurements of antennal jomts (average from 8 specimens): I, 0.064 mm.; II, 0.056 mm.; III, 0.186 mm.; IV, 0.127 mm.; V, 0.134 mm.; VI, base, 0.090 mm.; VI, filament, 0.270 mm.; total length, 0.927 mm. Winged viviparous female (fig. 7).—Measurements of antennal joints (average from 8 specimens): I, 0.082 mm.; II, 0.059 mm.; III, 0.300 mm.; IV, 0.223 mm.; V, 0.215 mm.; VI, base, 0.110 mm.; VI, filament, 0.395 mm.; total length, 1.384 mm. MOLTING. The time required for molting, from beginning to completion, is 30 minutes. The first indication is restlessness; the antennz are waved continuously and the legs move jerkily. This period of restlessness continues for 10 minutes, after which the antenne are allowed to come to rest close down upon the dorsum. A few minutes later the tip of the abdomen will appear transparent and baggy, due to the old skin having slipped backward; the head and eyes are now being freed. It appears that the skin first ruptures in the cephalic region and only splits a part of the length of the dorsum, the insect gradually working its way out from this extremity. After the head, the antenne are the first to be liberated, then each pair of legs in succession, and after all of the appendages have been freed the insect has still to struggle somewhat to free its abdomen. These observa- tions were made on individuals casting the third or fourth molt. NUMBER OF MOLTS. Quite a number of observations were made on the number of molts and the period between the same, ft being learned that stem mothers, the summer forms, and the sexes molt 4 times only. To facilitate careful and accurate observations upon the number of .molts, a young wheat plant was potted in a 5-inch flowerpot. A circle of black paper was cut small enough to fit down in the top of the pot. A small hole was then cut in the center and the paper disk was then fitted closely down about the base of the plant. After the paper was in place the space immediately around the plant was filled in with absorbent cotton made black with waterproof ink. Then a young Toxoptera that had just been born was placed on the plant inclosed by a clean lantern globe, with a piece of new cheesecloth firmly secured over the top to prevent the grayish cast skins from being overlooked. Each cast skin was removed as soon as the molt was completed, and a record made so that it could not possibly be counted a second time. All observations recorded in the notes on molting were made in this manner. — —~ A EE my 62 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ During the summer of 1907, at Richmond, Ind., careful observa- tions were made on 7 individuals of the summer forms, and in the fall Mr. R. A. Vickery, of this bureau, made observations on 6 indi- viduals, 3 of which proved to be males and 3 oviparous females. In each case there were 4 molts. In the spring of 1908, 4stem moth- ers were found to molt 4 times only. In the spring of 1909 at Lafay- ette, Ind., 1 stem mother was found to molt 4 times. Later on in the summer, Mr. T. H. Parks, of this bureau, ran a series of experiments with the summer forms and, of the 30 individuals under observation, some of which were winged, he found that all without exception molted 4 times. In the fall of 1910 several additional oviparous females were found to molt 4 times only. This makes a total of over 50. specimens that came under our observation, under conditions that would absolutely preclude error, and there was not a single excep- tion—all molting 4 times. As it was found that the period between molts varied, experiments were begun in the summer of 1907 at Richmond, Ind., in order to learn how great the variation was when each individual was subjected to the same conditions. This experiment was carried on indoors and all individuals were subjected to the same conditions. Table II will show the variations. TaBLe II.— Variation in the duration of the different instars in Toxoptera graminum. ag From time | From first | From see- |From third Individual. of birth to | molt tosec-|ond molt to} molt to ~ first molt. | ond molt. | third molt. |fourth molt. H. m aH. ™ TE Se oo ire Sk wae Ramee Do 38 35 28 29 LSE ene Se SS 2. ae re aR ne 40 15 29 #15 ss Ea) ENE EA, 50 20 26 40 Lee SAS Be EE SRSA SA ae 45 54 his scl iy A il ily ee ea OO Ae MEE en Ope igor Naren A 44 30 - 32 35 There is also considerable variation in the time from birth of individuals to the fourth molt and the appearance of the first young, as will be seen from Table III. Individuals in Table III are the - same as in Table II, with the addition of ‘‘F” and ‘‘1b*.” TaBLe III.— Variation in the time from birth of individuals to fourth molt and appearance of first young in Toxoptera graminum. Fadividwal: From time of birth to |From time of birth until fourth molt. first young appear. Hours. Days Hy. Days. Pe ere Pe eo re en tae ae ee ea ee 143-144 5.9 144 35 6. 02 SS ret ope. JE. Sea Joe) Bis ae See oe 143 5.9 148 6.1 ee ES Sea ae One a ee te eae ee Se 153 6.3 164 6.8 Prtek: eaianiwin So ce Coen es abet Ade ee eee en eee 153 6.3 165 6.8 er ee eo BRE oe ee ee ee ee 204 8.5 246 10. 02 A ae 2 es, SS ee ae OEE et as Ot 195 8.1 205 8.5 ee ne rs Pe oe ie, SS ee ea ee 170-175 Ta 2175 (pr 1 Proc, Ent. Soc. Wash., vol. 10, Nos. 1-2, pp. 11-13, 1908, 3 Approximate, NUMBER OF GENERATIONS PER YEAR. 63 BIRTH OF YOUNG. In the fall of the year 1907 adult individuals of Toxoptera were brought from out of doors into a warm room, placed under a micro- scope, and observations made on the manner of birth of the young. The embryonic young within the body of the parent are inclosed within a thin, transparent, structureless membrane that corresponds to the vitelline membrane in the true egg. Normally, in warm temperatures, the young Toxoptera frees itself from this enveloping sac during birth. At a temperature of about 60° F. or below, the young are oftentimes dropped before they free themselves from the sac. In this latter case, upon landing upon the surface of the leaf they expand and contract gently until the sac is ruptured at the cephalic extremity and they are freed from their prison. NUMBER OF GENERATIONS PER YEAR. During the summer of 1907, at Richmond, Ind., a study of the continuous, generations of this species was begun and followed through until December 10, the sexual forms and eggs being secured from bluegrass in the fields in October. With some of the young that hatched from these eggs (stem mothers) March 27 five lines of continuous-generation studies were begun and continued until the appearance of the sexes and eggs in the fall. These eggs were carefully retained and taken to Lafayette, Ind., where, upon their hatching on the first day of the following April, two more lines of continuous-generation studies were begun and continued until ended by the appearance of the sexes -and eggs in the fall of 1909, as was the case in 1908. oS ere ee “O.1nYe -10d Wd, -elouas -eloue3 “2s a Bera te NN Malte foe te rt Ans De fn etl ae ee ee ee ee eee lees 0 9 P > . a) ova |Fee act sah| em laren adv nt elses ore secendl ween let rf aera case cea ergo grey peel boeredfpehaed on ag A . bewe el viet o's esau] ev eee liesaus'|* cons | ee Ale .- . Te ee a ee sai reese |e pod i _ : ele ees s eeenell> wiaue se q t Gg Zz ¢g 19 e : wow ccleeswclecewsiesesclececesiosces|secesiosecel|sceesi|es Seales Sn te close . Be | aes -. eet eceleosseel|eeeces|eoseesiseeseeisossas 0 fp a OL 86 a weccecleveselacnecclecevelsnccélaoastiacsenisososeleonns|seneen . 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SSS es ee 4 ee eae eee Ce eee ea el i eo ae a aT a S @ 4 zi Zi gi gi gj.2) zl él § ei g| Eig] Fie i el @ | ai kl/elei el elas ol pt eg gt | pt ot a a » & chet ot et ot ans! b* ot ch 09 99 a =a ms g ll 2 lie} g 5 et 2. | BE Seloeliaeia/SoaliSsslee| SS | oPlorlSaloa!] wm | SF] B 5 i 99 5 @ 5 g & E ad a | BR/PeIEElEEleelealrclPelPeleele, (FL |PFIPT|@|F. 18/8 |e )8)/8)/8)eoa}e) 2 EU PBT SP PAP a ) me) el] | on m| 9 wee | Be } TER | Boe 8B) EE | B| | «| w| 6] gl &| Bl & PY ed BP Pe Le LT Bo Pp Pl BT a] &) | 8) 2] 8] 8] 8] 8] 8 ARS Se CR ORE Sees : : [‘poreoddestp 10 polp==— "U10d =] ‘savas ONT ="snoundiare yum popua pun snosdrina ym unbag sariagy ‘Sp))0CT 7D apowu suoynauasg”: ‘aja ‘saunjouaduag ‘uoyjonpoudas fiyvop buanoys sarivas Uuoyniauay “wunurunsb niajdoxoL, 64 "suyngln °C iL "q ‘606r “xa ee EL IG < — ee SE 7 ——y — i = - a eee PY che a ath Fore i a <= ry ~ < Pe eA owe "Sajep osey} WO SUOT}ZVAIOSGO ON 1 nas aR Pattie che weed | ecigteta | aceon eas 7 spe Naa aa i al poe eae aah 0 (D 1) Se mee ee eal re agar ceili aiacaehleabeaes (i ness a ase G ) ceil (iene (aperiias atieaatee iete eee ifer cea’ cor! | sas |e Rays 1 eae Wa 0 | naam nent ictal [Maca leach e (DRA A due Hoje floLon, a ae rea ee Go Ie emer at la lle Bae | | tis peas TZ | 96 | 02 sda oe me CORG eo mmere es wana Mee Lh dar gel fe ee OL | 96 | 61 pia ee v rie elie eG eee Me ae ce ena: oe 69 | &6 | 8T ‘ae OR eGo elles cll ean es ate St ae aaa ta pine Dihe \ BBE kk -— D ceed ee en A I awe "189 | 96 | OL Pe Te ill SI ey Ata I ee tila fbr aah ila Faerie Urea lt enc © aa a Re el ela wae i = it lo 69 | 26 | ST Seen ene a ee Te a ial a ea a le Ml Dc all oc Ol a i nt cel ac la alg RM Us | Ces i | i a ame elie le ie | es r9 | 16 | PT Cos tees AEE el PORE Roepe eacined Geer eee tee erin | ened aercn cle it ret licen jecdparcice.scvol| Se Oy oll notaca etores wemall ah ake q eee Ce ee es i i ed en ee i ry eee ee ey eee ee sles eee ele ee ewe Se se ewes NUMBER OF GENERATIONS PER YEAR. g & Vv V L ZL & v G ¢ 9 0 SOO e (EER CIO aan ace loci (secs cloacae locke silat als halle ik nati een aus ctalle 2 Sa) Palo Seialseeme etek ales ree[ereeeel g 0 0 0 0 0 0 0 0 0 0 0 0 26675°—Bull. 110—12——5 ' Wee cia heel ciara ced acerdy lees wast wr RA lect betes ees Sree nl Dali tke ope help cee Oo, eka co a 62 a8 Se i es i ee ed ee ee ee de es ee ed SOOCONHMHHMOOHRHARMAMOMOCOCOCoCocCoc“cCOCcCUCcCOCCOCOCOCO oo Yen} x io) Si N eele eee el eee le eel eel ele 0) z pple iach bic cbse sie lebeptabllc ak utd & gcd eo eae a eS ie saad Weasalveds dleveciduwe. sli suvelsvuedepden|vowcceleureedfanarae| pe” ([E) Teovevsll ccelbireeeeleigred|anwresl Reve seided aeveeclantes) ln ee rleediadl es CaN ONC ae z Aaa Seaiilsycs alerted twas vlbhcevlpnece| Aimee ha Peviulepetgg nocdaenl Mecbed ie tee slip tansianerculaescdMcte. pene | E> | EE « 1 68 Dik Fp RSIS Hoe i Phat be : 4 0 v4 0 es . ee ee ee vl L6 22 ene ee se ene Pel sa peli ett ok cece | hd baa |e rae arte aA be 0 0 0 See ewe ee wee ele ee lee ele ele ele ele ele ele vA RO 1% ‘ 1 seeee a . es ; . . even hie bee wae 0 z 0 wow eww le www eee ele eee lew ee ele eel eel ee lel ee WL 66 0% aS 5 seeee see eae . “* one eenee eennee oe 0 1 0 “* eee eel e eel eee ee see ew ela ne «leanae es eeaelen ene el 66 6 o wonee ed . . eee seen eeeee neue alew eww wl ewes 0) 1 0 oe ee ewww ele eee ean eee seeewe eeueleene . eeeewlane . eae GL 06 SI $ B Erne Foie rales elie Ken pata eraee eis teleeeeealeeeeeeleneenal I OQ [eters Owen tal dita onl Mele cralltahiig alate St SS rele ren tere | 66 | LE ; ( eee eel eee eel eee lee ell . . we ele ewe ele wee wl eel . . q il 0) re ed oe . sane eee ele www ele ee eee eee welew een wles eeonleww eee tL 06 OL ; eee ww let ewe ee eel ele le wae eae see eee eel www wel eee ne eee ee nee () z . eee ener eee ele ee ele ee eeeeelew naw wle sew el eee O8 6 gt 2 : > eats. . pareve wees er sieee en re seen ( V een, . one Sen e ele ewe wel eee ee ele ele ee eel ele LL ZOL ai o 1 Ainge oe RRC OP eee eee eee ee eee eee ee eee eee ee ed ry ae ee ee 2 ee eee eee ee we ER ERT OEP MICRO ee eee eee ee ee ee ed ey 2) ed ee he eee eee eee eee ee ee ee eee eel eee ee ele eee eel eee ele eee ele ee ele UG ya oune “OOGL N 4 ai. USAT, | Ta THE SPRING GRAIN-APHIS OR ‘‘ = “m0T} qQuseyzmMoy | -eieues glen “m0 -eieues 9 yiueelxIs “mon mitue! “" “MOI}eloues UPXIS "HOTeietes UIT “moTeioued ISM J "mm pirat ‘one Lod uF, "WOeicues Gus, “uoreleues q1moyz | n ~elauas quseysry | ne -Jaies YUUse]USAIg | "mon eisues WI “spas §=69yyueeqyly “m0 -eietes «86 UeAaTy “mon -Bioues GUL] “HoIyeIeues TIWGATS | -Bieuad | | | co ‘ponuryuoy—sawas OAT “snowdiid YM papua puv snosvdiaia ypun Unboeg sors) iyo) ‘suyngian “CL Aq ‘Cor “xa ‘suyyncr yp apo suoryvassqQ ‘oa ‘saunqosaduag ‘woyonpoudas hyvop Burmoys 8arza8 Uoynisouesy “wnununib vegdoxoy, "soyep asol} WO SMOT}BAIOSqO ON 1 wee ee ee eee ee ee ee ) eo eS eee Cm ee me ee wwe HO Re wee we EERE EEE EHH CHEE EHH SHEE EE SHEER ELE HEHEHE EH EEEE oS $6 ‘ 1a PS eesesscon SCSOCCOMR RR ANMANRANN “ydag weeeealesase ree eelo ten ele emma ms ee rms em ele see elccens q SOOCOCOCSCCOnANANNARANANANnAAANMnMoOoCoooooOCoCcoOoOo oO ’ ‘ x ii 5 oma) oO re rm oO NUMBER OF GENERATIONS PER YEAR. icy?) =) < THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ ~ 0 0) 0 0) 0 0 MOAT, onesie -Ue3 TINO}-ATUOAT, | e) Ay “mor TxIS- “mone “mon eio “ued pitq}-AyUeA TL, “moneie -u8s © -Ue3 pu ooes-AJUAA J, | AT, | “T0118 -Isues 3sIg-A7Ue SOSOSSOANMBIWIAMWMBANANBAANANCH HAF ONAQS Sono : } | | ' : “mon -eloues lsUeA, ‘suyoqia “CL &q ‘606r “ay, AP CE? | SR - | A Wa | aw wa analy pn Aa linc pce ats be ge ol | doin chp i etal abel eA ale aia eed a Pl Gee Oo) nce Cette Cn coe Cette Clone Cenonn Getcen Getren be tenn Penne Cited Eerenn Chnenn bhenre Coenen Geren ae en) Ceo Oecd ee nod Chon Gente COenod Chtnng Cenenn Gelnod Chnnnn Ehtnnn Gettin Gttns Cnnenn bnrenn beteen benren ie Ge COE CeCe Celce Coen CeCe on Cele Cotten Ennoe CP tend Colon Conner Enonon Getenn Cenenn beeeen Cerrar breren go teers [ecterefeceecefec see efeee reefer eee efenes aed peel main cll pe ch as a ath cot aid 8 an oenell ora na A eca oll Wie hes ca z Ah a mnie he's nip piel pil Saige pa aired |.s acne l\esded el Rass tl le cn Sell ad Rolly nnd cakaadial hia Ranta ae ean ae z ie Glee eon Benno Benne Bette d Bettod Penne Eetnnn be tenn bitenn Ehtenn Cloned Crennn Chntnn Cerne Ceeren bereer g 7 Gao) God enn Benne Cele Getto Bettnn Chtenn Cennnn bennnn Cltnnn Glenn Cetrnn Coren Centon Crore Pennine z i Gade) Geen Genes) lend Gnnend Gentnn Centon Cnlnnn) Pe nnnn Pelnne Chetnn Chnenn Petre Genren nennn Preenn cere z Gade) Gee Gennes ee nnn Chnnnn Centon eennn Cnt nnn be nnnn felted Clrenn Chtnen) Petr Cltnnn Crennn Eerenniercern Pe LO [tetttc feces te feceecefeceec fect ece feces cafes sees fee eee lec tere leceeeeleeeeealereealereeealertereleeserelereeeeler eens ; To [ttrttcfecccetfec cece feceeeefeee ee e|ee eee eleeeereleeseee|ecteealeresee|ectereleseeee[ersereleeeereleserslereeeeler snes } Wi Gee Geog) Conn Cele Coed Coen Bonn COP noe Cente Cleon Color d Cece od Conon es Geoeoo Coe oen Peer oe cere z (i Gee) Gee Renn Cnn nod Cente Blte nn Centon Ce nen EhCn cg Glennon Pntnnn Cerne Cetoeo Conor e Pencen Coe non Cece er ° ee ee RSPR ELSES? (RRR | apr | RRR et || apes > Ee (Ee ei |e ERS Pe ees ees ant et aN ‘mon -BisUes Y1Use10U0IN "mon -elouad ques ysig “mone -Iste3 YJUse]UeAsg “mort -eioues )Uee]xI ‘ponuru0j—saxes OAT | | “mon -eioues 4 ]Ue0];T | “mor -gieues [1U303IN0 FT L "mort -eieue? Yue ONeisues Uys, | : “con -eloues §48 9 UeAaT Wy “MOM eieues Ue, “MoIeieues UUIN ! "MOl]e1eUes YIWGAVS | "Honeieues WWUYSIq “MoIeieues YXIS © “MOI eleues UII “morNeisues TING JF ‘snosndiand Yun popua pun snoundrara yum uUnbag sarwag ‘spy 0(f 7D apvUl SWoYjndsasgC— ‘aja ‘saunqgouadua ‘uoyonpoudas hpop Buamoys sores Wornseue’y ee “MONeisues PUY, | “MOI}eIIues PUOIGS “WOI}eleues ISI | ‘oinye -10d 110, T WO ‘unuvudib 1.127 OXxO, J, 69 YEAR. S PER YE TION NUMBER OF GENERA SSCCOCSCCSCCOR HON HO OH 101910 H | q SAN OOAN 09 HOD HOD SO HOO HOD OD OD MH ODION ANANM MOM OA HOnOOCoCCOoCCOoOCcOo Se eee | a eae aie oe Saye | cela wie eee (S.e(ele))] aw es Cle)! @ «ees a)|\ale winiece | eta w (6) = |le'wikin is =]|'n.6\0 elute] es a ele ecules e-em ae Od Ce ied fi ene ee fe es Cd i nes far bP Nati) | MRR OCG CM EMT CT hh i | OY se tO Ae et OCH PCT TPS | ea ea a Med Ret yin flee ao ae Tt UP ner cies] Meni toe fe pe sean, Cs i i i a ia a Een P| soe ews See esse caine |e ah ees|anaen6|anesveloaseca|is on stae| sae eu sae od @ «|= pip ae willie Seen «il we omais|lia «ole Bw ’ ecw ewle ewes weeeweeleesenel(snewesisaeeas|esseee sew senle sees sic naeeele nee selene nmes|sweaeslesionvelecsses|sosnesleceseeeleounweccsi|ecaace es {ee oo ete |e ee) oe ies Ser eie 8 ales Seeds ine eee ae eels ||elaip oe Re oe (ee e!|\eeie!e win) ete a we w/in wm Mime | {mihi 6 m/e we mt aioe! | mlest ie rw mrt] rere ey arl| isan wie amma) eccecetvace te we eeelee EE eS Ol Siew Pe SS | Se ae ees) wee eel ale ew ae eee © allie 6 eTet Oe)! \n we © 6) we] salsa a) elie we mie w;| ete ree & as|\m ete ate (a: | ile mae me) |' ai eee ie | foie ee sete relma eter Cd ies eae’ iar Cee at 2 eae es we pe st Saw ee |e ee we eee ae wee = oe wus wave le ole||\e. ee eis 6 | wie «= alee alan oe lees cu a] @ ee bale we eo sin |) ee ee hie Sd rs ey SE) SRS S18 a eS we S| eS Sas eee ee ee 6S eee ele oe lee Se oe eee eiaie je m | ohm ime a) ol alae wm | iti el mia| cette weet im mime enim il\mrwimsm rem lim em ei we es er TE | SS RNA ST emf Ae Sm OS me | ema em ae me) a we |e me | ee | Oe © ee ewe © we) eee eee |e lee wie, wti|\m we aiitelie! w!||wim mm tate | ms) etc vec) || felon) sitet le es ey a es or i See eS |S eee Se 660 e i's) a ee wed ae ee ee) ee eee |e mele w) |e a See we) me oe weve] ee ein el ee w mg all Pee pw, ew) |e, ie wie ke ell eel ele intl litem @cetitillw. ole cecice ee Se | Re OP OO eS he See eS )) eee = ea) a 6s oS eles «aes aes ees a wave simi) 6 dese elma =a | ee ob Wi s| ete Gram a'|'e 6 ee e'e)|ite aa eiiel|le wie ere eillere w acm-alte/meim ee eeweel(semssl(mecewe(s cee nslesaeeelenaweslesesnacelisceceecleuc rd es er ea eww el ew ee ele ee we ele eww ee eee ee ed ee Se Sseaeslecoevelsaeanis|s@peesles@aasicveaneeleecenamiianawwe|sences|sauues|eniewee ee ad ee i a ees es wee ee pitted ti re ed oe ee ed ene ee es ee es ed i re! a ee’ eas -- F088 | 2 OE a ae 8 OSS) Sees eee 2 we 8) Soe -e Se!) ane ee lise = amis |\e'e Wim a allie a cn = os de eine |= =o « sieie wt bie = s| a ei = © ole « ape mol ere Cd i ir re ‘AON 70 THE SPRING GRAIN-APHIS oR ‘‘GREEN BUG.”’ Mr. T. D. Urbahns, of this bureau, carried on a series of check experiments at Dallas, Tex., in 1909, starting in March and ending in the fall. (See table, pp. 64-69.) As will be observed, and for reasons explained farther on, he did not obtain the sexes. By these experiments the maximum number of generations was secured as described under rearing methods (p. 51). The maximum number of generations in 1908 among the five series of continuous generations was 21 and, as shown below, occurred in series I of first-born; the mini- mum being 6 in series FF of the series of last-born. The complete series are as follows: Series B, maximum (from first-born), 20 genera- tions; series BB, minimum (from last-born), 9 generations; series C, maximum (from first-born), 18 generations; series CC minimum (from last-born), 8 generations; series F, maximum (from first-born), 16 generations; series FF, minimum (from last-born), 6 generations; series G, maximum (from first-born), 19 generations; series GG, minimum (from last-born), 9 generations; series |, maximum (from first-born), 21 generations; series IJ, minimum (from last-born), 10 generations. If all of these be added, we will find the average to be 13.6 generations. This will represent the approximate number of generations for the year. In 1909 there were two series reared, A and B, both resulting the same. Series A, maximum (from first-born), 18 generations; series AA, minimum (from last-born), 7 generations; series B, maximum (from first-born), 18 generations; series BB, minimum (from last-born), 7 generations. The average for these two lines would give 12.5 generations, a little lower average than at Richmond, Ind. Mr. Urbahns carried out one series of first-born generation experi- ments at Dallas, Tex., in 1909, from which he obtained only the maximum number of generations. He began March 31 and finished November 3. In this time he reared through 25 generations but did not ascertain the sexes, neither was he successful in finding them in the fields. It appears that the species will vary in the number of generations produced from individuals hatched the same day, and from the off- spring kept under the same conditions throughout the year. This will readily be understood when the amount of individual variation ‘in molting is considered. AGE AT WHICH FEMALES BEGIN REPRODUCING. The age at which females begin reproducing varies greatly between spring and summer and between fall and summer; as between spring and fall the ageisvery muchthesame. At Richmond and La Fayette, Ind., Toxoptera begins reproducing at from 5.9 to 16 days between the middle of May and latter part of September. From the time of hatching until the middle of May the period is from 20 to 27 days; — REPRODUCTIVE PERIOD. 71 from the latter part of September to and including November the _ period varies from 12 to 53 days. A case occurred in the autumn of _ 1907 where it required 53 days for a single individual to reach ma- turity. This individual continued to live up to the 10th of December, when all experiments were closed. The average period from birth to reproduction for the summer months, early spring, and early fall is 9, 22, and 19 days respectively. The average for the entire year, or for the period in which the species breeds, parthenogenetically, for Richmond and La Fayette, Ind., is 16.6 days. In arriving at these averages, all individuals of the generation experiments for 1907, 1908, ~ and 1909 were considered. Mr. Urbahns found that at Dallas, Tex., the period varied from 7 to 12 days from birth to reproduction, from March to the middle of May; from 6 to 14.days from the middle of May until the last week in September, and from 9 to 11 days from the last week of September to November 3. The average number of days from birth to reproduction for each of these periods is 9.6, 7.4, and 9.7 days, respectively. Mr. Urbahns reared a number through December up to the middle of January. During this period the time between birth and reproduc- tion was very much greater, varying from 18 to 25 days, with an average of 20.5 days. The average, beginning with April and con- tinuing until November 3, is 8.9 days. From the foregoing data it will be seen that under favorable conditions Toxoptera breeds much more rapidly in the South than in the North. All of the reproduction experiments upon which these figures are based were carried on out of doors, but the insects were protected from the hot rays of the sun in the summer. . REPRODUCTIVE PERIOD. The period of reproduction covers a greater average length of time in spring and fall than during summer, being greatest in the spring, even though the maximum period of reproduction for a single female is practically the same for the three periods. _ In computing these averages each individual of all the lines of con- tinuous generations was considered, even though they reproduced for a single day only and then died or disappeared from some unknown cause; hence the averages are lower than they would be had these latter individuals not been considered. From this data it will be seen that both the maximum and the average periods are the great- est in the North, where the insect is able to breed continuously in unprotected places throughout the summer. At Richmond and La Fayette, Ind., the maximum period of repro- duction for individuals born from March to the middle of June is 45 days, the minimum 1 day, and the average 18 days; the maximum for individuals born from the middle of June to the middle of August 72 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’ is 43 days, the minimum 1 day, the average being 12.6 days; the maximum for those born after the middle of August is 45 days and the minumum 5 days, the average being 24 days, while the average for the entire season is 16 days. In Texas the difference between summer, spring, and fall is still more marked, December and January being about the same as the summer months. Mr. Urbahns found that during December and January the maximum reproduction period was 19 days and the minimum 2 days, the average being 8 days; during April and May the maximum was 30 days and the minimum 4 days, the average being 16.8 days; during June, July, and August the maximum was 16 days and the minimum 4 days, the average being 8.4 days; during September, October, and November the maximum was 28 days and the minimum 3 days, the average being 17 days. The average for the entire season was 13.9 days. LONGEVITY. At Richmond and La Fayette, Ind., Toxoptera lives for a much longer period in the spring and fall than in the summer. In fact, in the summer it often survives a shorter time than is required for it to reach maturity in the spring and fall. Those born from the latter part of March to the last week in May live from 15 to 78 days, the ayerage being 43 days; those born from the first week in June to the middle of August live from 9 to 57 days, the average being 24 days; those born from the middle of August on through September live from 12 to 75 days, the average thus being 40 days. The average length of life for the whole viviparous breeding season is 35 days. These averages are not made up from the maxi- mum and minimum alone but every individual in the line of first- born of the continuous generation experiments is considered. Mr. Urbahns found that in Texas the spring grain-aphis lived much longer in spring and fall than in summer. In fact, in the summer it was difficult to keep it alive at all, it being necessary to keep the cages in the shade.t’ He also carried on some reproduction experiments in December and January, and in these two months found that it lived from 25 to 39 days, averaging 34 days. In April and May it lived from 13 to 47 days, averaging 35 days; in June, July, and August it lived from 10 to 30 days, averaging 17 days; in September, October, © and part of November it lived from 11 to 56 days, averaging 28 days; the average for the season (from March to November) was thus 26 days. In making up these averages only whole numbers are used, frac- tional parts of a day not being considered. Also, all individuals upon which we had complete observations were considered. 1 Ante, p. 47. ‘7 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’ 73 FECUNDITY OF VIVIPAROUS FEMALE. The average person, unfamiliar with the habits of the Aphidide, would scarcely think it possible for such small creatures to become sufficiently numerous to devastate vast areas of grainfields, destroy- ing millions of dollars’ worth of property within the space of a few weeks. When one becomes familiar with their powers of reproduc- tion, however, the problem seems very simple. Prof. Huxley + states that the tenth generation alone of a single rose aphis, were all of its members to survive the perils to which they are exposed, would contain more substance than 500,000,000 stout men. Buckton,? commenting on Prof. Huxley’s figures, states that he much underestimates the real quantity of animal matter capable of elaboration from a single aphis in a year, and goes on to say: Basing the calculation, for simplicity, upon the supposition that every aphis lives twenty days, and that at the expiration of that period each aphis shall have pro- duced twenty young and no more, then at the expiration of three hundred days only, the living individuals would be represented by the following figures: Aphides. Days. Aphides. i Lune yc eel Re a ae oe | ie in lg ia eRe ye. =a peters inh 40207 2 le eee ADONIS OSA ea ae epeemraences 1m 100-205). . 222... 2-2625 25-2 ee ORs... sesceate ts Slat. sachs =e pepreauees: im 200—20.__....)... 10.240) OO ABD MOD 25% Pa. oc. cla Sash Joe ie ereuwecs in 200—20°—32 768, 000, 000, 000, 000, 000. .....---..2----2---.-.-. ae Again, if 1,000 aphides weigh 1 grain, and 1 man weighs 2,000,000 grains 1 man weighs 2,000,000,000 aphides. “* 3 900,000,000 =1,638,400,000 men; equal, perhaps, to the population of China seven- fold. To quote further: But a mathematical friend remarks that this calculation even does not express the real rate of increase, since it supposes the progeny of the first aphis to be produced at once, and not to commence producing until the expiration of the first twenty days. To this same friend I am indebted for the annexed calculation. If we suppose the progeny of the first aphis to equal 20 in twenty days, and this progeny to begin producing when five days old 20 young, each of which again on attaining the age of five days begins the propagation of 20 young, and completes also that number in 20 days: Then at the end of 20 days from the commencement of first aphis production peperemrin he aireet issue. 229022) PUES Ee SH = 20a At the end of fifth day, progeny a begin to produce, which at the end of first 20 days will altogether equal 15+14+13+12, &c.+2+1................--.-.--. =1206 At the end of tenth day, progeny 6 begin to produce, which at the end of the first 20 days will altogether equal 10+9-+8, &c. +241..-....-.-....--2-..-- = 55¢ At the end of the fifteenth day, progeny c begin to produce, which at the end of the first 20 days will altogether equal 5+4+3-+4241.....................-- == 5d Total at the end of 20 days equals a+6+c+d.................22--2.---- =210 The amount, therefore, at the end of 300 days (or 20X15) would not be less than the fifteenth power of 210, which is almost impossible to express in figures. There would be room in the world for nothing else but aphides. 1 Trans. Linn. Soc., vol. 22, p. 215 (part 3, 1858). 2 Monograph of British Aphides, vol. 1, p. 80. 74. THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”? Toxoptera, in all probability, would not fall far behind these figures and the number might even be greater. Be that as it may, the illustration will suffice to show us that Toxoptera, with such remarkable powers of reproduction, could easily overrun the whole country if not checked in some manner. At Richmond and La Fayette, Ind., the maximum number of young produced in 24 hours was 8 in June, July, and August. The maximum number of young produced by any individual was 93, in the month of July. In Texas Mr. Urbahns found the maximum in 24 hours to be 10 young in May, and the total number of young for one individual reached as high as 84 during the same month. At Richmond and La Fayette, Ind., considering the progeny from only the individuals of the line of first-born generations, the average num- ber of young for the summer falls below either spring or fall, the spring being in the lead. When both the individuals from the line of first and last born generations are considered, those of the fall average less than those of the spring orsummer. In 1908 the evidence was in favor of the line of first-born generations as being more prolific than the individuals of the line of last born. In 1909 the line of last-born generations held its own, especially in the spring and summer, falling behind slightly in the fall. In fact, in each line of generation experi- ments, the last born fall behind in average number of young in the autumn. Also, if an average be taken of the first and last born sepa- rately, the latter will fall behind. Considering each individual of. both lines in all generations, both first and last together, the results are as follows: The maximum number of young produced by those born from March to the middle of June is 69, the average number for each individual for this period being 30.3; the maximum for those born from the middle of June until the middle of August is 93 young, the average number for each individual being 25.3; the maximum for those born after the middle of August is 66 young, the average for each individual being 24. ‘The average number of young, including every ‘individual under observation, whether connected with the generation experiments or otherwise, for the entire viviparous breeding season, of the years 1907, 1908, and 1909, beginning the last week in March and continuing until November, both inclusive, is 28.2; there being 216 individuals used to obtain this average. In the generation experiments were a number of individuals that produced from 1 to 10 young and then disappeared, apparently not dying from natural causes. All of these were included, however, in arriving at the final average, as any average obtained by excluding one or more individuals from any cause whatever would be more or less arbitrary, since in nature the mortality, in all probability, would be much greater. All of the rearings were carried on out of doors, it 83 48 | N. 26 el eee Gowns Ree 56| SE 15 Seruay.-.....- 49 38 | N. 22 GCE fee eerie 84 64| S 16 A ATT sto. o ea acs. = =: 56 33 | NE. 20 Gales 2 do 85 64} SE 18 Ly [prea (0) 47 28 | NE. 19 Tal oleate es soe 84 64; S 15 6 | Cloudy... ...: 43 34 | NE. 15 Sol as ee eee 82 66 | SE 18 (Dba 60 39 | N. 22 Ct ae re) a 80 66] S 16 3,1 ( Cle 68 Sor NG 7 OR Sos oh: do 80 57 | W 23 Ue ee do.. 73 38 Ss. 15 141 SP ag oe do 85 65 | SE 21 UG eee do.. 68 42 N. 22 ANZ Se do 87 65 Ss 21 TN ee dos. ; 72 AAW ie N 10 TS ses do 80 70 | NE 17 eo fs don. 74 36 Ss. 10 HA eee! do 70 47| N 36 1153 eee Go>.. 78 46 Ss. 15 is iClear 2. 70 421 NE 23 UG Un | eae doz... 7 50 | N. 24 One e se CER cn ae 76 46 | SE 14 Wop lee os. OSes ae 70 40 N. 9 tr ieots cr; Meth | 30) 2 INW. 16 ry Rear do.....___.| s2) Stage 3B 9 fe eee tues 3] 2| NE. PR _ Sis do........| 1 Gia oo eA. do.......| #2] 24] NE. 9 Pa ees do........| 70| SINE} y RS i a a | 53] 30] N. 3 <1} ates do.........1 4%) .ene 3 Li aes 67] 2] S. 0 10 | Clear.._._____- 2] 39] N. 6 ~" Bier < “Os OY ES 7 Ny Set oe si} 49] S. 35 10 | Fair....-...-..| G&G] 28/NE 21 rr ae do.........| 84] GISW. 3 11 | Clear...______- 31 we. o 16 BT Gee. 73s] 44] S. 30 4 mee Petes: 79] 461SW. 2 vy pane 2 re Ko 583] 38] N. 20 i= | eee Gt. =< .-2 4 ») 47 | SW. 2»? (yy aie ES 64 39 | SE. it See Td eee do.........| Gi] 2] N. 20 CY ae Eee 75} s1|SW.| 2 =) eee do.........| @); 331SW. 17 7) Fair..........| 381 Gee “mu ee do........| 741 3518W. 15 18 | Clear._._..___- 2] w/]sw. 23 1 tee ee ee ee 0 rh Oy do.....--.| Si Gla are ; Yee do......._.| S81] 5 | NW. 32 3s eee do.........| Sse Py 19 } Clear________-- 41} N. 16 a des so} 6) SW. Ss 5 See NaS BE 41 41 S. 65 2 ne do........| S| Gi = PN ee 7 4: 1SW. 25 a. Wee i Gio 3 7. Bees de. te 5 soi E. 16 Mi dee ee 86 &! S. 2 | eT ee Sas si]/ 52] S. 233 r-# ae sl] e|sw. 31 ry). Se Oe ae 44 | NW. 3 26 | Fair....______- 3! 67|Sw. 31 2% | Cloudy... ----.- 58 42 | NE. R i oe i) oa eee 3 #2 | sw. 31 | var... | 71) «| SE. i8 yee do........| 923° .aeGne 30 27 | Cloudy... -__- 61 54 | SE. ij 29 | Clondy..-._._- 73 3 | NW. 4 ae da... |) Ma) a ee 28 4 Gee | wl ai NE “os Mar. 1] Clear..._____- 56| 37|NW. 24 PS Oe do........| 59] 49|NE 21 giey Peack de... | a] atsw.f 33 ' i Taste V1.— Marimum end minimum temperaiures, with direction and velocity and character of the day, Oklahoma Ciiy, Okla., 1907. s, i Di- 1 poe tion a of \wind. ; nd . : per : or. | °F. Ll RF. kour. Mar. 1} Clear__........ 49| 2] N. 30 33/ Ss. = 7 ee. ; eRe 36 S5 68] 35] S. 35 8] 8. 5a = g Cs do........| @] 37] E. 23 58 | SW. a9 4} Cloudy..._.-_. 81] 4; S. 36 54} N. 36 oe Ge: 225: : 5] 34} N. 36 2] N. a | eae Taheae e/ 8/8 | 33 8|SE.]| 1 Wowie. eo} 44] N. 34 |) 47| N. 240 8 | Cloudy... ___-- 54/ 35] E. 25 4] N. 3 4 es ST 71} 33(|NW.| 47 41) W. 31° tc eat | 35] N.] 35 sis. | 2 11 | Cloudy........| 7} 39] 8. 36 | a2] N. ie wires... 22... 6s} 43] S. 30 2] N. 3 13 | Cloudy... .__-- 44 2 | N. 32 33 | NE. m4 ye; ee 54] 27| N. 2 “/ 8. ‘6 Ec. ae eee 62 36] S&S. 3 49 SE. | > ee ee: Sis. 71 #2; 8. 38 34 | NE. > YRS ae $s} 52] S. 37 34 | SE. rr. 5. ie ae ss) @! Ss. 35 41] SE. _) ee dauct.. 2 7); @! S. 32 39) N. 2 | Cheer... 52. 2 @/] 61/ 8. 25 |) 36 | NE. a ie. 22.5: so} 64) S. 32 44 | NE. st %} &]| Ss. 34 | N. | Se si] 64] S. 31 36} 8. 24 | Clondy...._. ss 54] S&S. 35 &2/ 8. 7) Wale * 2: $ {| 64] S. 33 2} N. 26 | Cloudy..._.... ri 67} S§. 7 35 | NE. 9 Ra PS Se Ss] 6] S. 33 55] 8. ~ aE =). ei &. 2 51| SE. oe EE 6s/ 4] W. 2 34] N. SE Se aS 70} #21] N./ 31 22] N. 31 | Cloudy... .._-- 55 44], N. | 3 INFLUENCE OF WINDS ON DIFFUSION. 87 TasLte VII.— Maximum and minimum temperatures, with direction and veloeity of wind, and character of the day, Wichita, Kans., from Mar. 20 to May 31, 1907. + / | 2) | . . Date ht: Mini- ree oe Date Maxi-| Mini- rec A a (1907). Weather. um.'mum. “— ty of || (1907). Weather. | aum.|mum. an ty of ; ee ca oT reat ba Fane Pe Ce a ee ee 4 Miles | Miles 4 per ' per , SoBe aiite rete hour. OFT a | ice hour. Mwars 20!) Clear.......-. 87 51 | SW. 16 |P-Atprs 0260) Clearce- cece a5 63 31 | SE. 13 2] See Oe. Sa aia 91 63 | SW. 24 PF (NBL Tk eee 77 48 | SE. 19 2) DS ae 92 63 | SW 24 23 Clem ys. 2 63 41} N. 18 PamOlear..- =... 7 64); SW 21 74: al | Sones BO eee oe 41 Soa Ne 27 A en 2) (SiO Ee aera 85 54] S. 19 SOA) silaire 2 oe Ses oe 49 S0:h ON, 16 7 | eae toe eee 89 62 | SW 24 |} May 1/] Clear......... 61 31! SW. 9 26 | Cloudy.. 78 69 | SW 28 altars. Seles so 67 45] E. 14 C7 i a 69 47 | SW 17 Si eGlotdy 2555.55 51 30] N. 27 Zen Cloudy... ...-. 79 527) We 30 4 Apa ee ete ee 50 28 | SE. 15 D4 OG: ae 68 39 | NW 15 5 | Cloudy.......- 50 43 ; NE. 13 - | Se 68 42| N 21 Gylheaee PAGE pees oe 51 45 | NW. 15 | COas saeee 57 39 | NE. Li, Cnpxse Tee ee 57 46 | N. 9 mere by Clear.........- 65 By Ge ess 24 ih OL 2 cee ne 66 50| N. 12 PMB AIT SS 2). 2. (gl 49 Ss. 30 sol | ee 2 A032 <8 72 49} SE. 9 2) OER a 81 56 | NW 24 AOS WORE Reese 79 51 | NE. if MEANT 2 oa 71 44/1 NE. 26 AP Clear aoe ae 80 52 | SE 20 OW eee. (C24 60 39 | NE 20 ta espe Opes 55 82 60; S 35 Go Cloudy....---- 57 49). BW, 15 1s Cloud y23.2 552 79 50] S. | 24 Whe eesee,= (ites 62 44| W. 23 i eee Dee eas 53 Seal oN 20 8 | Clear..... 60 41}; N 30 154] eHaine. weet oe 66 33 | NW 22 Oi eeier:< oeeeie 74 30 | N 23 16°) (Clear = cee a2 82 44 16 PON ap eh ccf 63 39 | SE. 16 Df) SP air es oe 90 60 | SW 19 wreipe@lear.....-.--- 66 44 | NW 23 1380] Cloudy= 3. o=5 86 58 | SW 12 ee. 2 GO ers 22 55 36 | NW 26 19 Ci ee eee eRe 71 58 | NE. 14 Lt Dee 53 28}; N. 13 20) Cleat poo. 79 50 | SE. 16 pia eCloudy—.. .. _- 52 36 | SE. 22 2 BAe enc ee 85 61 | SW. 24 ie | doe ee 74 46] N. 18 Dei ClO AR ie cie Pw, =, 5 85 65 | SW 25 Gn Cloud yo... . 51 29 | NE. 22 GAS Vel G4 Reape ae Ba fe 86 66 | SE 1g TENS eit a &8 25 | SE. 14 24, | Cloudy <=... .- 75 64 | SW 17 i fel ee SUC Spe be eee ie 53 bay Ne 25 25 Bets oe 82 55 Ww 14 1 ee ee Tee 53 Sle. NE 14 2 eek cash 65 48 | N 26 20 } Cloudy. p 52 37 | NE. 14 Da NCICAT cs, i 66 of Le 14 ee = 8 Ca 58 3451 Ne 9 28 | Cloudys.5— 2 9--. 54 54) SW 16 22 \- GOs f= Ses = 56 43 Ss. 11 7S el [ees WOes e548 59 69 10 22) |) (Oleh a 73 36 | SW. 17 SU eee do 25268 61 61} N 13 1 bo Oeste 81 45 | SW. 34 ie eae Gor eise:s 65 65 | N eat <2 53 | 36 | NE. 24 Taste VIII.— Mavimum and minimum temperatures with direction and velocity of wind, and character of the day, Dodge City, Kans., from Mar. 20 to May 31, 1907. : Direc-| Ve- a Direc- aE Date r Maxi-| Mini-| tion | locity Date axi-| Mini-| tion /locity (1907). Weather. [num.tmum.| of of (1907). Weather. | mum.|mum. of | of wind.| wind. wind.|wind. Miles Miles er per ioe he ae at ee ee hour Rete) Mair... ...... 91 41 y oA ane, 6.) Hair..oie see! 63 41 |NW 23 2 geo ae 94 54 | SW 28 QilnClear: sesseck= 73 40 | NW 16 225] oe CD Igeaoee 89 43 28 10 nese d0.5.. 77 37 | SE 27 23. | (CCE ee ee 76 53 | NW 23 Ge oe @orss-42 64 38 | NW 24 24 |. Ozcisee 86 46 26 1p Ag| ae OT eee ne 59 35 | NW 15 DS) || 12ers 89 46 | SE 30 13}; Clear <2ea5. Se 55 28 | E 13 Bean ese = doz... 85 54 | SE 36 iL Sie ee ences oe 68 35 | SE 26 Pee a, 2 GOsker sn so. 61 38 | NW 16 Drs ARES «So ces at 70 39 | NW 23 A Goes. 74 44 SE. 35 16%) Clomdye. << 5% 48 24| NE 14 eeeneiear. 5.2... - 62 30 | NW. 24 ae h@lear.. 22 Ge oe 60 24 | SE 16 30) Cloudy... ....- 59 31 | NW. 18 1a); Mammo So. 35e2 51 32 | NW 18 a 31 AILS. 55 34 | SE. 16 49; Cloudy.22 5 b< 45 30 | NE 10 Seep. 1 | Clear.........- 72 36 | SE 28 Ai jassae do..3. 46 33 | NE 9 2 ats... 85 51 23 i | eae On sack a 48 28 | SE 10 mnoleane: 2. io. 73 49 | NW 22 Sol ME aire 55.22 oer 56 35 | SE 9 Ag GlOUGY sa. 2-0 58 38 15 93>) Clear. o2 se Scie 78 30 | SE 18 5 Baim cay: «Sere 61 26 | SE 10 DAA & 3 One 76 36 | W 24 Gaile: a Oss ce 67 39 | W 25 95) (Cloudy... ==: 44 31 | NW 17 We CleATS <5 5... © 66 SEI SRY 12 QB AC Wai ot oes 64 28! SE 18 88 THE SPRING GRAIN-APHIS OB * caber” Bue.’ =a Taste VIH.— Marimum and minimum tem peratures with direction and vélociiy of wind, and characier of the day, Dodge City, Kans., from Mor. 20 io May 31, 1907—Contd. ELE | Milez °F. | °F. | hour. Sy Fay | 37] N. 16 } 3) W. Ww i 2 ee 16 } 16 £2] SE. a SB} N. 18 | 7 53 | SE. iW =» | NW. 7h is 55 | NE. B 37 | SE. PI 19 So} N. w a2 | NW. 18 } 1 3} sz. 2 7 i NW. in| 2 @ | SE. 33 27 | SE. 2 fF 22 & | SE. F<] 41/ SE. 8 i 33 64] SE. 32 #2 | NE. 7 24 55 | SE. 29 | EK. S Zi W. 41 8] N. | 6 | 33 37 | NW. E ) o| =| wi i | | 2/SsSE] S|NW.| 5 3 | | #2ISE | @ | SEK.) 24) 29 |. 6)/SE.| 2 6 | SE} 31), 30 | N. ll 39|NW.| 17) 31 | NW.| 24 34 | Nw. 16 | - ; H) INFLUENCE OF TEMPERATURE ON DIFFUSION. Directly and indirectly, temperature is responsible for the destruc- tive abundance of Toroptera graminum in the United States. Di rectly, because the species will breed throughout the winter months at a temperature under which its natural enemies will remam imac- tive, and besides, it is probably due to this influence that the sexual ~ forms and eggs occur, so far as known, only over the northern por- tion of its range. Our extended investigations have led to the sus- picion that, but for the viviparous reproduction in such overwhelm- ing numbers in the South, during winter end early spring, to dnift northward with the season, there would be little if any damage caused by its occurrence in the Northern States, where in fairly severe win- ters it probably winters over in the egg stage only. For this reason the authors have thought investigations of the egg and its development of decided economic as well as scientific importance, and the junior author has therefore made a brief study of the em- bryology of the species. The temperatures prevailing over the country where Toxoptera has worked its most serious ravages, and departures from the normal during the season of greatest activity are all given on the tempera- ture diagrams, Nos. I to V (pp. 15, 21, 25, 26,28). The upper numbers indicate the normal temperature, the lower the departure therefrom (‘‘+” meaning above and ‘‘—” below). Each separate page relates to one of each of the five consecutive outbreaks. From these it will © be seen that outbreaks of Toxoptera have succeeded only winters with ~ INFLUENCE OF TEMPERATURE ON DIFFUSION. 89 the temperature in the South above the normal, followed by springs during which the temperature was below the normal. The tem- perature during December, 1902, was below the normal in the South- west. (See Diagram IJ.) In January, 1903, it was above, but below again in February, and about normal or above in March and April, the result being that only incipient outbreaks occurred in northern Texas and probably South Carolina. (See Diagram II; fig. 5, p. 20.) If the series of temperature maps (Diagrams I-V) be compared with those showing the area covered by each invasion the relation between abnormal tempefatures and these invasions will be clearly apparent. These records are those of the United States Weather Bureau and are therefore correct so far as general field temperatures are involved. When it comes to a consideration of the exact effects of temperature and humidity upon the individual Toxoptera, however, the figures will not apply with mathematical exactness, for the reason that to secure this information it is necessary to learn the exact conditions in the midst of the insects themselves at the exact time that such data are being secured. To illustrate, the instruments of the Weather Bureau kept in the shade may indicate a certain tempera- ture, yet in a field perhaps a mile‘distant on a sunny day, and down among the plants in the midst of the developing insects, there may be several degrees difference in temperature. As will be noted farther on, Mr. Luginbill has found this difference to amount in some cases to several degrees. Besides, it is easy to conceive of other conditions which might have precisely the reverse effect. Further- more, there will be a difference in temperature as between fields with a sandy and a clay soil or between a southern and a northern expo- sure, or with a soil dry on the surface as against a soil with a wet sur- face. It will be observed, therefore, that while the exact tem- perature at which Toxoptera will reproduce, viviparously, is of scientific interest, such information is of minor significance in the field, where it is the more generally prevailing weather conditions, such as are secured by the United States Weather Bureau, over wide areas that become of greatest importance, Mr. R. A. Vickery, on December 4, 1908, at Richmond, Ind., with 5 viviparous females under observation, found that young were produced sparingly at a temperature of 40°F. This was indoors, in a room slightly heated by an oil stove so that the temperature was under control, and frequent readings were made during the day. Under the same conditions numerous young were produced when the temperature reached 45° to 53° F. 90 THE SPRING GRAIN-APHIS OF ‘‘ GREEN BUG.”’ Tabulated, the results of Mr. Vickery’ s rearings are as follows: | Taste IX —Experimenis with 5 viviparous females of Texoptera graminum to determine minimum temperature at which reproduction will take place. Richmond, Ind_, “4 December, 1908. : a ae — young | | produced. | i Dec. 3 » Ss ry 4) 4 | 1 5 2) ~ 6 Lr] +) 5S | 6 7 25 aaa | 1 = 3 50 ry S 3 |i 30 0 After December 9 the outside temperature increased so that con- trol indoors was not possible. At Dallas, Tex., January 3 to 14, out of doors and under natural conditions, with thermometer within a few feet of the five female Toxoptera 1 to 3 days after maturity, Mr. Urbahns found that young were produced as follows: TasLe X —Erzperiments with 5 viviparous females of Toroptera graminum to determine minimum. temperature at which reproduction will take place. Dallas, Tex., January, 1908. F Grebe Sconanne | INFLUENCE OF TEMPERATURE ON DIFFUSION. - 9] Further observations made by Mr. Urbahns on these same dates with eight additional females, the offspring of which were not counted, are of much interest and are given herewith. January 3. Two reproducing. January 4. Four reproducing, 1 pupating. January 5. Five reproducing. January 6. All torpid, seemingly frozen. January 7. All torpid, seemingly frozen. January 8. All torpid, none reproducing. January 9. Seven reproducing, 1 still pupa. January 10. Seven reproducing, 1 still pupa. January 11. All torpid, seemingly frozen. January 12. All torpid, seemingly frozen. January 13. All torpid, seemingly frozen. January 14. Adults and young fallen from the plants and lying on the ground. All except 3 inactive. One female of the first five died on the 10th and nearly all of the others survived but a few days; only one was alive on the 20th. During the spring of 1908 the junior author was engaged in an extensive series of rearing experiments at Richmond, Ind. Both plants and insects were kept out of doors in a small rearing house (see Pl. II, fig. 1), with a thermograph placed in their midst, so that exact temperature changes were continuously recorded. Plants were grown in flowerpots and over them in each case was placed a lantern globe with the top covered with cheesecloth. Whatever the effect of this inclosure and cover might have been it was evi- dently uniform and, therefore, affected all of the viviparous female Toxoptera on these plants to the same degree. Taking five viviparous females, each a stem mother, colonized separately on single plants, in a precisely similar inclosure, and keep- ing a record of the number and date of young born, we have the fol- lowing tabulated results: TasLe XI.—Effect of temperature on reproduction of Toxoptera graminum, Richmond, Ind., 1908. Tempera- i Tempera- ure, | 2, ai Number young pro- | To- ae Number young pro- | To- Date. |———— | duced by each in- | tal Date. —_—__——| duced, by each im-1) tal Mini-|Maxi- dividual. No. eas Maxi- dividual. IN 0. jmum. mum. : mum. lmum. ; ea PUD do Oe ) OF a. St | Apr.18...) 55 Ea) nga ete jhaie Al Miea 1 se 6: ||) May to: 29 56 yO) OT ey Oe 0 Ie. 50 0} 4) 2) 2 1 2 11 ae 35 AE Oe 4S Leh Bact 3 Zoe.) 38 Sidley al ne PA a el a 6 3 hati 2) Cit ll el oP 6 Biles 33 GS ull ce ah lo ity lead 7 a 41 50 hel sn IO Date a 0 Bees | 85 Fe Siva ial a fake is ia cag Ducane Bea Os One Oi ee 1 ciel Oo kL Ty A ART ea eS BE ove 49 AOL. [uot bee Oa G 5 ears) 60 ZA oes em Fac: il gpa Vi Na! a Menace 41 SSO SU | Prey: vo 1 25...| 61 ib eA BO eee ae Sohne At 49.) td) 0 Loh Ooh ale od SOE) 5 SOS} oye | Ov] 14 —| |—— ee 7 fee 42 67 Oi eee Zl Mattel BOGE pa ste ee ON BP eS6) S|. TA eee or aie lS eae | es ee YO 2 || Total progeny during 29-ee | 736 Sy OSS Re ie is iE 7 MIO D= ie kewoueencces sue 60 | 47 | 69 | 39 | 29 30225 | 33 47| 0} 0 | 07] 0 1-0 | 0 | 92 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.”’ Of the five individuals involved in Table XI the two last hatched from the egg March 24, the other three on March 27. This table indicates the influence of high temperatures on reproduction, but also shows that these affect the individual female to varying degrees. The totals for the life of individual females show that all of these were in the vigor of life, not having reached the decline at the time the observations were made. These tabulations are taken from records of regular rearing and reproduction investigations, and were selected wherever there occurred a number of. consecutive days with temperatures varying both above and below freezing during each 24 hours. By referring to the continuous rearing by the junior author it will be observed that with favorable conditions a female Toxoptera will produce young every day during the most vigorous portion of her life, the exceptions being toward the close thereof. It would probably be well to mention in this connection some observations of the junior author in regard to the amount of cold that can be endured by Toxoptera. On November 13, 1908, several viviparous females that had been producing young were frozen solidly in a block of ice. They were thawed out after 8 and 24 hours, respectively, and all died. These may have been somewhat weakened by age, however, so on the 14th 2 oviparous females, 1 winged viviparous female, 1 adult viviparous, and 2 individuals that had cast the third molt were frozen in a block - of ice and allowed to remain so for 24 hours. About an hour after being thawed out, at a temperature of about 45° F., 1 oviparous female and the winged female turned dark and died, the others keep- ing color, but showing little signs of life. About 3 hours after there were signs of life among the remaining ones; 7 hours after thawing out they were still feeble; 24 hours after thawing out the temperature was raised to 60° F and 1 molted. On the third day after being thawed out there were 2 young in the cage. Six days later all were dead except the one that was giving birth to young, and her progeny. This will give some idea of the tenacious grip Toxoptera has on life. Attention may properly be called to the fact that unless the utmost caution is employed in the examination of plants for newly-born young there is great likelihood that some of them may be overlooked. Thus they may be born one day under a high temperature but remain undiscovered until later, when the temperature is much lower, and of course be credited to the later date. In the light of all of the observa- tions made by those engaged in these investigations, the minimum temperature under which reproduction begins is about 40° F. Pos- sibly reproduction may occur under some obscure favorable circum- INFLUENCE OF TEMPERATURE ON DIFFUSION. 93 stances at a slightly lower temperature, but these instances are probably too infrequent to become of economic importance. With the eggs in the North the case may be more important, because these, deposited in dead leaves of bluegrass, and sometimes probably buried under several inches of this matted grass, with the living leaves covering this over, the temperature and moisture would both be greater than at several feet above ground without such protection. Mr. Philip Luginbill of this bureau in April, 1911, proved this to be true. He placed a thermometer in just such a position as men- tioned above, in a protected nook where the sun could shine directly on it in the grass and no wind could reach it and found that the temperature was 10° to 12° F. higher than when the thermometer was several feet above the ground and in the shade. The junior author has found that eggs are deposited in just such places, and that hatching takes place in spring at a temperature ranging, as recorded by the thermograph, from 32° to 62° F. It would appear that eges deposited in a position as mentioned above would hatch sooner than those deposited in places where the temperature would not be so high and the stem mothers from the former would reproduce, the pest becoming more abundant in the spring and making its way from grass to grain earlier and in greater numbers than they would from the cooler locations. This leads us to a very interesting and important point in tem- perature effects on the species. Inthe South, seemingly south of about latitude 35° to 36° north, it has been impossible to find eggs of this and other species of aphidids in the fields. There is in the perpetua- tion of the species no apparent need of this stage, however, as it is able to continue throughout the entire year reproducing viviparously. In the North this is probably not possible except during very mild winters. The situation is therefore about like this: Gradually as we proceed southward from about latitude 38° the sexual forms and eggs disappear, while to the north of about latitude 36° hibernation is confined more and more to the egg stage, until this becomes ex- clusively the state in which the winter is passed. The practical, economic importance of this is that there is con- siderable doubt relative to the amount of injury the pest would cause north of this belt of country if there were no Toxoptera drifting in from the south. In other words, but for the countless myriads developing south of this belt and sweeping over and beyond it, there would be few if any destructive ravages. If this is the true state of affairs, the oats crop north of this belt is to a certain degree de- pendent upon the success or failure in controlling the pest in Texas, Oklahoma, New Mexico, and South Carolina. Summarizing, then, it would appear from the information we have been able to obtain, and which is given throughout this publication, ‘GREEN BUG.’’ 94 THE SPRING GRAIN-APHIS OR together with that contained in the various tables and diagrams relating to temperature effects upon this insect: (1) That mild winters are of much more vital importance in Texas than they are in the latitude of southern Kansas and northward, and (2) that the influences of abnormally warm weather, if the temperature rises high enough, have the effect of bringing about activity among the parasites, which has a restraining effect upon the increase of Toxoptera. In the North, where the pest winters over wholly or largely in the egg stage, warm winters are of less importance, while abnormally cool weather during spring and early summer exerts a far greater influ- ence. This fact renders a study of the embryology and temperature effects upon eggs and stem mothers necessary to a full understanding of the entire problem, extending as it does over both North and South. The fact just stated is somewhat peculiar and was unexpectedly revealed by the combined studies of those engaged in the investiga- tion of the insect, and called for a study of the development of the egg, which has been carried on by the junior author with the results given in the following pages. The most important influence of temperature is, of course, upon the development of its principal natural enemy, Aphidius testaceipes, further discussed in connection with the studies of that insect. EMBRYOLOGY. Although the development of the parthenogenetic egg in Aphididz has received considerable attention from several authors, that of the true egg has received very little study. Hence the junior author has given a limited amount of time to the study of certain important phases in the development of the winter egg, as contrasted with the winter condition of the viviparous insect in the South. Not wishing to duplicate the work of the other writers, who have confined their studies for the most part to the earlier stages of develop- ment,-he has begun with the formation of the blastoderm, his main object being to follow the principal stages of development of the embryo through the fall until growth is checked by freezing tempera- tures, to note the time when growth is resumed in spring, and to observe the effect of varying temperatures on development, all of which has to do with the fluctuations of the insect in point of numbers in the North and relates to its economic importance, besides balancing our knowledge of the insect at a corresponding season in the South. Most of these studies were carried out at the University of Illinois under the supervision of Dr. J. W. Folsom. We are deeply indebted both to him and to Dr. W. M. Wheeler of Harvard University for their kindly criticisms and helpful suggestions. EMBRYOLOGY. 95 METHODS AND MATERIAL. The material used in this investigation was collected in the autumn of 1908 at Richmond, Ind., and in 1909 and 1910 at La Fayette, Ind. The eggs were killed and fixed mainly in two solutions that are practi- cally the same. The first was a saturated solution of bichlorid of mercury (corrosive sublimate) in 35 per cent alcohol, 95 volumes, and glacial acetic acid, 5 volumes. The second was a saturated solution of bichlorid of mercury in 50 per cent alcohol, 94 volumes, and glacial acetic acid, 6 volumes. The fixing fluid was raised to a temperature of 75° to 80° C., poured over the living specimens, and allowed to act from 5 to 10 minutes, after which it was replaced by the same solution, cold, for an equal length of time. The specimens were then washed in 70 per cent alcohol, in which they were kept until sectioned. Gibson’s fluid was found to be a very good killing and fixing agent also. For sectioning, the following evita was employed: The eggs were punctured with a fine needle, dehydrated, and kept 20 to 30 minutes in paraffin of about 54° C. melting point. They were oriented in a watch glass (that had previously been smeared with glycerin) with a hot needle, under a binocular microscope, the bottom of the watch glass being first quickly cooled with a little cold water. The eggs were cut with a Minct-Zimmermann microtome in sections from 8 to 13 y in thickness, attached to the slide with Mayer’s albumen fixative, and stained with Delafield’s hematoxylin or by Heidenhain’s iron-alum-hematoxylin method. Surface views of the embryo were obtained by dissection. For dissections it was found that the best results were obtained by using material that had been freshly fixed and washed. Grenacher’s alcoholic borax-carmine was used for staining in toto. GENERAL DESCRIPTION OF THE EGG. The eggs are broadly elliptical with a slight reniform tendency. They are 0.70 to 0.78 mm. in length and 0.33 to 0.45 mm. broad. At oviposition the egg is a very pale yellow, changing in a few hours, at a temperature of 50° to 70° F., to a faint greenish color. At this stage there appears an almost circular area of darker green at one pole of the egg; we have termed this the ‘‘ovarian yolk,” a brief description of which occurs in the following pages. At the end of 24 hours the walls of the egg about the ovarian yolk appear denser and of a deeper green. The germ band is now forming and invaginat- ing. During the next 24 hours this process is completed, the egg becoming a darker green in the meantime. By the third day a rod- shaped body can be seen near the center of the egg. This object is the submerged germ band. By the end of the third day the egg becomes black. ‘S GREEN BUG.”’ 96 THE SPRING GRAIN-APHIS OR Ali these changes can be readily observed with a hand lens by holding the egg up to the light. At low temperatures (below 40° F.) these changes take place slowly, 10 or more days being required for the egg to turn black, if the temperature is near the freezing point. The black coloration is apparently due te a pigment in the shell; the green color, to the developing embryo. At deposition the egg is coated with a viscous substanee which hardens in a few see fixing the egg firmly to the object upon which it rests. There are but two membranous coverings to the ripe egg, the chorion, or shell covering, and the vitelline membrane. The chorion is a rather tough, leathery, homogenous membrane which under a hand lens appears smooth and shining. With a com- pound microscope very faint lines or cracks can be sometimes ob- served on the surface, although usually the surface appears perfectly smooth, with no markings whatever. The vitelline membrane is structureless, colorless, and trans- parent. Under the vitelline membrane is the peripheral layer of protoplasm. This layer is very thin and very finely reticular. It is continuous over the surface of the egg, the cleavage cells lodging in it to form the blastoderm. Internally the egg consists chiefly of a compact mass of yolk granules, supported within the meshes of almost clear protoplasm. The yolk granules are structureless and subspherical in shape and vary greatly in size, ranging from 0.0027 mm. to 0.013 mm. is diameter. At the posterior pole of the egg is a large, dense, almost spherical, granular mass. These granules are 0.0019 mm. in diameter, are as uniform in size, and the central area apparently takes the ae slightly as though it were a chromatinlike substance. As previously stated, we have termed this mass the ovarian yolk. It is evidently not homologous to the secondary yolk of the parthenogenetic em- bryos. The ovarian yolk is formed approximately at the same time as the formation of the main yolk mass of the egg, while in the case of the parthenogenetic forms of aphidids the secondary yolk enters the egg as the blastoderm is forming. It appears also, from our material, that this ovarian yolk is not exactly homologous to the ‘“nole disk” described and observed by Hegner (1908), as we have not been able to observe that it affects the nuclei in any way, nor have we found any cells which we think correspond to his “‘pole cells.” The function of this granular mass seems to be the nourishment of the developing ovaries, and we have therefore called it ovarian yolk. It is not entirely used up in the early stages of embryonic growth, and remains in close proximity to the developing ovaries throughout the later stages. lh i a ars . a a a “ou | Jn EMBRYOLOGY. 97 Tannreuther (1907, pp. 631, 632) states that in the species he studied some of the follicular nuclei of the wall of the oviduct which _ enter the posterior pole of the egg divide several times, the chromatin breaking up into smaller parts and becoming vesicular. These small vesicles then usually unite and form a common spherical mass, though in some cases they remain isolated. In Toxoptera graminum we find no trace of true nuclei within the ovarian yolk (the homologue of Tannreuther’s secondary york ‘of the winter egg) until the blastoderm is formed, at which time cells may be found that are apparently migrants from the primary yolk. OBSERVATIONS. For convenience of reference 9 consecutive stages of development are here designated, as follows: Stage 1 (Pl. III, fig. 1)—Blastoderm just forming, only part of the surface being covered by the cleavage cells. Stage 2 (Pl. III, figs. 2-4) —This shows early and later stages of invagination of the germ band. The position of the ovarian yolk in relation to the invaginating germ band is shown here. Stage 3 (Pl. IV, fig. 1)—-The germ band is still adhering to the posterior pole of the egg. Stage 4 (Pl. IV, figs. 2, 3).—The germ band is entirely submerged in the yolk, is tubular in form, and uniform in thickness. Stage 5 (Pl. IV, fig. 4)—During the fifth stage the germ band has differentiated into the amnion and the germ band proper. Stage 6 (Pl. V, fig. 1)—The germ band shows differentiation into layers, and the fundaments of the segments are evident. Stage 7 (Pl. V, fig. 2; Pl. VI, fig. 1)—The fundaments of the ap- -pendages have appeared and the invaginations for the stomodzum and the salivary glands are evident. Stage & (Pl. V, fig. 3; Pl. VI, fig. 2)—The appendages are much longer, and the invaginations for the stomodeum and proctodeum are well advanced. The latter is not indicated in Plate V, figure 3, as the last segment curves backward too far. Stage 9 (Pl. VII, figs. 1, 2, 3, 4)—The illustration of this stage is intended mainly to show the manner in which the embryo reaches the surface and the position of the dorsal organ. In Stage 1 (Pl. III, fig. 1) the blastoderm is beginning to form. As _ the cleavage cells become more numerous within the yolk-mass some _ of them migrate to the surface and lodge within the peripheral layer _ of protoplasm, where, according to Tannreuther (1907), they divide _ again, the protoplasm of the nuclei merging with that of the periph- erallayer. The formation of the blastoderm takes place more rapidly in the region of the anterior pole, the posterior being the last covered; 26675°—Bull. 110—12——-7 ce 98 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ the entire layer is then one cell in thickness. The blastoderm, how- ever, does not cover the surface of the ovarian yolk. Not all of these cleavage cells reach the surface; many remain behind, increasing in number within the yolk. These latter cells are indistinguishable from those of the blastoderm. Figs. la and 1b represent two of these cells magnified 845 diameters, showing them to be star-shaped masses of protoplasm with a large oval coarsely granular nucleus, more often with a large clear area of nuclear sub- stance around the mass of chromatin granules. At the posterior pole, about the ovarian yolk, the blastoderm be- gins to thicken and to invaginate (Stage 2, Pl. III, figs. 24). This is the beginning of the germ band. At this stage (Stage 2) some of the yolk cells apparently pass into the ovarian yolk. Tannreuther (1907, p. 631) states that the thickening of the blastoderm is caused by the rapid division of the blastoderm cells of this particular part. We find, in addition, that some of the cells from the interior of the egg migrate to the posterior pole to assist in this process. Each of the cells of this thickened area is very elongate, and, from a surface view, now has a somewhat polygonal shape, with a large coarsely granular nucleus. The growth of the cells of the germ band carries the ovarian yolk toward the center of the egg (see Pl. III, fig. 4). The part of the blastoderm that invaginates first becomes the posterior part of the embryo, and that part that invaginates last becomes the anterior portion. In Stage 3 (Pl. IV, fig. 1) the germ band is ready to free itself from the blastoderm. The former is now cone-shaped, the base being closed by the ovarian yolk. When the germ band releases itself from the blastoderm, it leaves behind what we have termed the ‘‘polar organ:”’ A cluster of cells embedded within a mass of protoplasm. These cells soon group themselves into a more or less spherical mass, with a less dense vacuolar area at the center (see Pl. IV, fig. 4). In later stages this central area appears denser and structureless, as though filled with a fluid, and is of a yellow color, not taking the stain, and opening © directly upon the surface of the egg. For these reasons we suggest that it may be an organ of excretion. When development ceases in the fall, this body is still present. What was formerly the blastoderm now becomes the serosa. The cells are much more widely spaced now and this wall is much thinner, except at the anterior pole, where the cells are apparently crowded more closely than before. Some of these cells often show large — vacuoles on the side toward the yolk. At Stage 4 (Pl. IV, fig. 2) the germ band is completely submerged in the yolk, has assumed a tubular shape, and is near the center of © the egg. The walls are of uniform thickness and composed of a com- EMBRYOLOGY. ug pact mass several cells thick, some of which are vacuolated, and having a coarsely granular nucleus. Figure 3 of Plate IV shows a cross section—slightly oblique, however—of the germ band. The yolk granules of the primary yolk are now more numerous near the embryo. In Stage 5 (PI. IV, fig. 4) the germ band has clearly differentiated into the amnion and the embryo proper; these gradually merge into each other. This differentiation apparently takes place by a gradual migration of cells to one side of the germ band. The cells of the amnion at this time resemble very closely those of the germ band proper. The germ band begins to fold in this stage and its anterior extremity begins to broaden and flatten. The ovarian yolk has de- creased in volume and has assumed a more anterior position in rela- tion to the embryo. The yolk cells in both the primary and ovarian yolk have lost somewhat their amceboid character, and now consist, each, of a large granular nucleus, with a much thinner area of pro- toplasm about it. The primary yolk granules are smaller and much less numerous than before and are collecting in masses about the yolk cells, with indications here and there of a partition, or wall, forming between them. ‘This stage is reached by the end of the second day, under favorable weather conditions. The “polar organ” and protoplasm at the posterior pole contain a large central vacuolar area now. In Stage 6 (Pl. V, fig. 1) the germ band has greatly increased in length, is folded upon itself, and almost forms a loop, the anterior and posterior extremities nearly touching, and both pointing to the posterior pole. A portion of the posterior extremity of the germ band is again folded upon itself. It is now differentiated into three layers, which we take to be, respectively, ectoderm, mesoderm, and ento- derm. The ectoderm and mesoderm consist of a compact mass of columnar cells, two cells thick. The entoderm is much thinner and less compact and forms an almost continuous sheet over the inner sur- face of the germ band. Its cells resemble yolk cells very closely. In this stage fundaments of the body segments appear as slight elevations of the ectodermal surface. The ovarian yolk has assumed a more anterior position in relation to the embryo than in the pre- ceding stage. Between the ovarian yolk mass and the germ band is a croup of cells that have apparently separated off from the mesoderm. From this group of cells, in later stages, the generative organs arise. The amnion now covers the ventral surface of the embryo and the other surface of the embryo is in contact with the yolk. The amnion is a very thin, delicate membrane, its cells being widely spaced and quite small. The intervening protoplasm between the cells of the serosa has become more constricted and the cells have taken more of an elongated oval shape. The primary yolk has now become defi- 100 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.”7 0 nitely segmented into more or less spherical masses, separated by thin walls, each area or mass containing a number of yolk granules — and from one to several cells. The polar organ is now almost spher- — ical, with a central, pear-shaped area of dense, structureless, non- — staining matter of a yellowish color, and an anterior opening. Al — though this evidence is insufficient it possibly indicates that the fune- — tion of this organ is excretory. The embryo reaches this stage of development about the third day, under favorable conditions of temperature. In Stage 7 (Pl. VI, fig. 1) the embryo has changed its position so that from a side view it has the form of a reversed figure 6. The — portion that in the preceding stage was folded upon itself ventrally — has reversed its position and folded back dorsally. The ovarian — yolk is now in the region of the first abdominal segments. It is in ~ contact with the embryo, and the group of cells that separated it from the embryo in the preceding stage has assumed almost a spheri- | cal form, and a more posterior position, forming the genital organs later on. The three primary regions, cephalic, thoracic, and abdominal, are now sharply marked. Each region is distinctly segmented. The — cephalic region has 5 segments achalasia the thoracic 3, and the abdominal 9, the last abdominal being relatively quite large. There are now 15 conical appendages. The antennez arise from the pos- — terior margin of each cephalic lobe. The labrum is between and slight-- _ ly anterior to the antenne. The mandibles are nearer the median plane than the fundaments of the maxillz and the labium. The next three pairs of appendages represent the first, second, and third pairs of legs. Plate V, figure 2, represents a surface view of stage 7, show- — ing the embryo straightened out and the position of the appendages. All of these appendages are evaginations of the ectoderm, cross-sec- tions showing an external layer of ectoderm cells and an inner layer of mesoderm cells. | _ The stomodzeum (PI. VI, fig. 1) appears now as a simple invagina- — tion of the ectoderm, the posterior wail of the labrum forming its — anterior wall. The proctodeum has not yet appeared, The salivary — glands (Pl. VI, fig. 1) are represented by a deep, bilobed, ectodermal — invagination between the cephalic and thoracic regions. There is — now a star-shaped mass of protoplasm about the nucleus of the — ovarian yolk cells and the yolk granules are grouped around these cells. The primary yolk is grouped very much as in the preceding stage | with the exception that the masses are smaller and do not contain as many nuclei. The polar organ is smaller than formerly, with a smaller number of cells. It still contains a yellowish mass and communicates with the outer surface of the egg. 03 Bul. 110, Bureau of Entomology, U. S. 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Fig. 1.—Longitudinal section showing the blastoderm partly formed, being farthest advanced in the anterior region. The mass of ovarian yolk is lodged at the posterior pole, Figures laand 1b represent the yolk cells magnified 845 diameters. Fig. 2—Longitudinal section showing the thickening of the blastoderm about the ovarian yolk previous to invagination. Magnified 156 diameters. Fig. 3.—Longitudinal section representing the germ band at the beginning of invagination, folding inward about the ovarian yolk. Magnified 156 diameters. Fig. 3a.—Section of the blastoderm. Magnified 430 diameters. Fig. 4.—Longitudinal section of a more advanced stage of invagination, the germ band having almost closed over the ovarian yolk. Magnified 156 diameters. (Original.) ‘ainyjnosy jo "Jdaq “Ss "fq ‘AZojowojuy jo neaing ‘911 ‘Ing “HH 3LV1d Bul. 110, Bureau of Entomology, U. S. Dep OU (o} 200% fo) <2 Ste OxoC ce) oO! 9 60s ) Pe) ce nes SOE Ws ce) O 500°00,00-GO ee oo rey re OR OS050S0L09 Bul. 110, Bureau of Entomology, U. S. Dept. of Agriculture. iS) gd 4 Oo od} S90 tr SoC eRR OSE ON Re olgga% SCOOSOGSIA SRO OARS, SSOGOSOROSO OSBORN fey oe REOSVS: S88 gi ¥ te PASTE’ 006) 2: kins 209 Oe “OS Oe0td; a9} < oSoORS 50. Of Ae) is OOS eee a Ye Eee} 066,° os aucreeunentie repeal ©) oOo ~ a O! 89905950. O5O59 0% Sw ROLGVGS Bo oO Od OK fe (C, Py: OLOOE LHW O gs ews ? z SOs sou Or PLATE IV. ; 0; Ba 109 POSS, eeevoses So S080. 883202000" ‘00,0 060 9 O85 02098 C0 Cre) oon Po g AES, te) 23 fo) 68 ce) ° Cae Sho o oe a 9 9.00, 0 ©, oO. 0 co} Op O80. OS, SEEDS So %> GeO § sohesions 2 © 9 0 Amn’ BASE FBO SISOS 0.05 09": SS QOS 0° DEVELOPMENT OF THE EMBRYO IN THE EG@ OF TOXOPTERA GRAMINUM. aped germ band ready to release itseii irom the surface of the fig. 1.—Longitudinal section representing the somewliat cone-shi Magnified 156 diameters. merged within the yolk, the anterior extremity being n’’ is represented by a mass of cells and propo plast at the pos- egg, the ovarian yolk closing the tubular germ band completely su posterior end closed b terior pole. Magnifie diameters. Fig. 4.—Sagittal The ovarian yolk has taken a more anterior position. (Original. ) pos ietlor extremity. 119 diameters. the ovarian yolk. The “polar orga Fig. 3.—Transverse a e section showing the germ band folding and differentiating into amni The “polar organ’’ is vacuolated now. Pig. 2.—Sagittal section representing the continuous with the sides and the oblique) section of the germ ban Magnified 156 on and germ band proper Magnified 156 diameters. (somewhat PLATE V. Bul. 110, Bureau of Entomology, U. S. Dept. of Agriculture. “SIoJOUIVIP OCT PoyTUseW . JT oimsy ¢ IA 9 (‘[RUISTIQ) “S1oJOUTeIP OST peyTUseW *Z OINSY “TA OFC[d JO MOTA OBJINS—"E “BIT 48] q JO MOLA 9ORJINS—Z ‘SIT “SIOJOUIVIP OGT poyTuse, ‘“TepNoiTo Ajavou OLOUL MOU ST ,,UVS10 IejOd ,, OAL, *IBAO UB SOULODEC 104-8] yey} stjeo Jo dnois B Aq 41 WL] poyeiedos sured YOA wepIVAO oY} ‘Tjosit wodn 4sourye peploy pu "ANNIAVYS VHYSLdOXO]L JO 9D SHL NI OAYSWA AHL 40 LNANdO1SASqd SIOkV] VOI} OJUT poyerUoIoyIp puvd ULES oy4 SuIMOYS WOTJOVS [ey{1IseG—'T “SIT O Ca a 4 ASP iw hy Oe see CO See COU 5 t. — | | eg Sa gp tle a 4 get meat th tan han ace A! STi i mt AERA 4 ’ ‘ Bul. 110, Bureau of Entomology, U. S. Dept. of O O O r Pa 05 ro) z& gd 09F a'Q0- 30 4 GV of ~ ete) : @o oi O EEE tiv are) &. C ¥ Ho O08 EAl©) O eee) 2 lee OCT SE ea ine ‘ ( O Por nS oe Kes ee, Bul. 110, Bureau of Entomology, U. S. Dept. of Agriculture. amb oy Sn We PO neh og o_ 20 | PGs le} 2010 Jo ne co 2% a2 soho SZ fl G a 0.02 fi PO A= oO 2 ir e\09 © fo 9 FARE: 0 900 — io O.Os> oO ss ‘ aye. nat rc Soi REIONN PLATE VI. DEVELOPMENT OF THE EMBRYO IN THE EQ@G OF TOXOPTERA GRAMINUM. Vig. 1.—Sagittal section of the embryo showing the se ominal region. Magnified 156 The fundaments of the ovaries have assumed more he ovarian yolk is granular and its cells are breaking down. ken up a position at the anterior portion of the abd hich opens upon the surface of the egg and is filled with a yellowish substance. h more advanced stage of growth than that of figure 1, the abdominal region having reversed its posi- olk. The mesenteron is in process of formation. ‘T ( Original.) I=; The invagination of the salivary glands is now evident. -6 diameters. Magnified 1 an yolk is greatly changed in appearance and has ta ying a muc gmentation. slightly oblique) show ( rge, somewhat pear-shaped central cavity w and inclosing the ovarian y »’ is much the same as in the preceding stage. ave shifted in position. The ovari yard ”’ now shows a lar 2.—Sagittal section tion by bending around baekw co He .cd Sas oS S Sot & 30 Oo HE = Ro DS ap n $3 .-53a 48408 AG eaO fo} eat. me C5: Bob ee B45 6.5 Deo se EMBRYOLOGY. 101 In Stage § (Pl. VI, fig. 2) the posterior or abdominal region of the embryo has now completely changed its position, having folded back ‘dorsally about the ovarian yolk. Plate VI, figure 2, shows a sagittal (slightly oblique) section of an embryo at this stage. There are ap- parently only 9 abdominal segments. Both the stomodeum and the proctodzum are plainly in evidence now, and the mesenteron is in course of formation. The latter is formed above and rests upon the ovarian yolk. This yolk now has a granular appearance, and the yolk cells within it appear to be breaking down. It is still divided off into subspherical masses. The polar organ is smaller than in the pre- ceding stage and the pear-shaped area in the center is filled with a yellowish substance as before. The ovaries are represented in this section by a circular mass of cells above the ovarian yolk. The pri- mary yolk is grouped and divided off by protoplasmic threads, very much as in the preceding stage, but is not quite so abundant now. Plate V, figure 3, shows a surface view of the embryo, straightened out to its full length. It will be seen that the appendages are now much more elongate, the thoracic appendages showing traces of segmentation. All the appendages are now directed posteriorly and lie flat upon the body. This is the stage in which the majority of the embryos pass the winter. It is very doubtful if any of the stages earlier than the seventh are able to survive the winter. Instances have come under our observation in which embryos in the sixth stage have been killed by very low temperatures. When heavy freezes do not occur until sometime in December, a very large percentage of the eggs hatches; on the other hand, however, when heavy freezes begin in November, large numbers of the eggs are killed in the early stages, since large numbers of the eggs are deposited in this month. An early autumn, therefore, followed by a severe winter, would limit to a great extent the number of stem mothers of the following spring. | Stage 9 (Pl. VII, figs. 1-4) represents the stages of growth occur- ring in the latter part of February and the first of March. When the embryo is ready to come to the surface of the egg (Pl. VII, fig. 1), it moves forward in the yolk until the cephalic lobes come into contact with the polar organ. It will be observed that there is quite a gap between figures 1 and 2, and at present we have no material from which this missing link can be supplied. Figure 2 shows the dorsal organ already formed. As we have no intermediate stages we can not state definitely whether this is the true dorsal organ or the dorsal and polar organ combined. It is probably the latter, as we do not find any traces of the polar organ at any other point in the embryo. It is very probable that the surplus cells of the serosa, at the time the embryo comes to the surface of the egg, collect at and group themselves about the polar organ, as there 102 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ appear to be a greater number of cells about this body at this time. There is no trace of the dense yellowish center of the polar organ, otherwise it resembles this body very closely. However, as we have lost track of this organ in the gap between figures 1 and 2, and on account of the close resemblance between it and the dorsal organ of other insects, we have designated it as the latter. At a later stage (Pl. VII, fig. 3) the dorsal organ has assumed a more nearly circular shape, the mouth having almost closed, inclosing a some-. what pear-shaped space. At a still later stage (fig. 4) the dorsal organ has released itself from the margin, migrated backward, and begun to disintegrate. At length it disappears by absorption in the body cavity. At first we were not able to note a revolution of the embryo, but later studies show that such a revolution does occur between figures 1 and 2 of Plate VII. After the ninth stage the development goes on very rapidly, and by the latter part of March the eggs are ready to hatch. During the fall of 1909 a number of eggs were collected that had been deposited in October and November, and these were kept until the spring of 1910 to note the time of hatching. No heavy freezes occurred until the 3d of December. It was found that although there was nearly a month’s difference in dates of deposition there was not more than four or five days’ difference in the time of hatching. An average of 64 per cent of the eggs hatched. We have also learned that eggs will not hatch unless subjected to freezing temperatures. SUMMARY OF EMBRYOLOGICAL DEVELOPMENT. There is a large almost circular mass of ovarian yolk at the poste- rior pole of the egg. Development begins almost immediately after oviposition, and proceeds more rapidly in the region of the anterior pole until after the blastoderm forms, after which growth almost ceases in this region. ‘The blastoderm originates through the migration of yolk cells from the interior to the surface of the egg. All of the yolk cells, however, do not take part in the formation of the blastoderm, part remaining behind to prepare the yolk for assimilation by the embryo. After the blastoderm is formed it is one cell thick and covers the entire surface of the egg, with the exception of the ovarian yolk. The germ band originates in the region of the ovarian yolk, where it invaginates and grows downward into the egg. The germ band is of the completely submerged type, the uninvaginated blastoderm becoming the serosa. Upon leaving the surface of the egg the germ band leaves behind it a group of cells embedded in a mass of protoplasm. This body the junior author has termed the ‘‘polar organ.”’ NATURAL ENEMIES. 108 The development of the embryo can be observed in a general way, with a hand lens, up to and including the sixth stage. This stage is reached, under fronowable weather conditions (50° to 75° F.), in about three days. A large number of embryos are nearly or quite half grown by the time freezing weather begins, growth starting again with the first warm days |. 4, aed sass of February. We have noted a revolution of the — grain-aphis: shell of embryo within the egg, and this revolution takes ee ae ee place between figures 1 and 2 of Plate VII. Eggs — Greatly enlarged. begin to hatch by the last week in March, the (Onsin4) typical appearance of the abandoned eggshell being shown in text figure 18. The number of stem mothers to appear in spring depends to a large extent upon the temperature of the preceding fall. ABBREVIATIONS USED IN Puiates III-VII. A., anterior pole. ms., mesoderm. ab', ab?, etc., abdominal segments. mz., Inaxilla. ab. r. abdominal region. o., fundament of ovary. am., amnion. 0. y., ovarian yolk, app., appendage. p., posterior pole. at., antenna. p. o., ‘‘polar organ.”’ b. c., blastoderm cell. p. p., peripheral protoplasm. b., blastoderm. p. y., primary yolk. c. l., cephalic lobes. ped., proctodeeum. d. o., dorsal organ. S., serosa. ec., ectoderm. s. g., salivary gland. en., entoderm. st., stomodeeum. g. b., germ band. th. app', 7, etc.,thoracic appendages. l., labrum. . . th. r., thoracic region. lab., labium. y.c., yolk cells. md., mandible. NATURAL ENEMIES. Toxoptera graminum is beset by a host of foes, without which we would be powerless to combat it. These enemies naturally group themselves into two classes: First, insects that develop within the body of the ‘‘egreen bug”’ and are termed true parasites; secondly, those foes that feed upon them externally or that take them directly into their bodies. These latter are termed predatory enemies. Under the true parasites we have A phidius testaceipes Cress., Aphidius ave- naphis Fitch, Aphidius confusus Ashm., Aphelinus mali Hald., A phe- linus mgritus How., and Aphelinus semiflavus How., all of which are ‘minute four-winged flies; under predatory enemies there are lady- beetles, syrphids, and cecidomyiids (two-winged flies), lacewing flies, and birds. Besides these, there are secondary parasites, or those that prey upon the true parasites of Toxoptera. These latter are as truly our enemies as are Toxoptera. 104 THE SPRING GRAIN-APHIS OR ‘‘GREEN BUG.’’ INTERNAL OR TRUE PARASITES. Aphidius testaceipes Cress. (Fig. 19.) Synonyms: Lysiphlebus abutilaphidis Ashm.; Lysiphlebus baccharaphidis Ashm.; Lysiphlebus basilaris Prov.; Lysiphlebus citraphis Ashm.; Lysiphlebus coguil- leiti Ashm.; Lysiphlebus cucurbitaphidis Ashm.; Lysiphlebus crawfordi Rohwer; Lysiphlebus eragrostaphidis Ashm.; Lysiphlebus gossypii Ashm.; Lysiphlebus myzt Ashm.; Lysiphlebus minutus Ashm.; Lysiphlebus persicaphidis Ashm. (=L. persiaphidis Ashm.); Lysiphlebus piceiventris Ashm.; Lysiphlebus tritici Ashm. DESCRIPTION AND IDENTITY. Female.—Piceous or shining black, smooth and polished, impunctured; mandibles and palpi pale; antenne brownish-black, sometimes more or less pale beneath, Fic. 19.—A phidius testaceipes, principal parasite of the spring grain-aphis: Adult female and antenna of male, greatly enlarged. Egg at right, highly magnified. (From Webster.) 13-jointed, the joints faintly fluted or grooved, the last one longest and thickest; wings hyaline, iridescent, stigma pale; legs, including coxz, yellowish-testaceous, the posterior pair generally more or less fuscous or blackish; abdomen often brown or pale piceous, with the first and sometimes part of the second segment more or less testaceous. Length, 0.07 inch. Habitat.—Rockledge, Fla.; Selma, Ala.; and Pocomoke City, Md. Parasitic upon an elated infesting twigs of orange, an aphidid on the cotton _ Plant, and Aphis avenz Fab. This parasite, which is probably the most important of all the nat- ural enemies of Toxoptera, has for this reason claimed more of our attention than all of the other foes combined. Hence a large amount of data has been collected, bearing upon nearly every phase of its development. Owing to the fact that large numbers of individuals have been reared by Messrs. Kelly and Urbahns from known par- PARASITE, APHIDIUS TESTACEIPES. 105 ents, both parent and offspring being preserved, Mr. H. L. Viereck, of this bureau, has been able to determine definitely for us the iden- tity of this species and to clear up the obscurity heretofore surround- ing it. He finds that it has been masquerading under 14 different names, and it seems that it may now be allowed to assume its right- ful Sa Mr. Viereck, after a careful study of all aimtecelia at hand, has sup- plied us with ie above list of synonyms. His work on thé revision of the genera Aphidius, Lysiphlebus, and Dizretus will appear later in some other publication. LIFE HISTORY. OVIPOSITION. Under favorable conditions the females begin ovipositing within a few hours after issuing, whether a male is present or not. When the female is placed in the presence of Toxoptera she will rush about Fic. 20.—Aphidius testaceipes ovipositing in the body of the spring grain-aphis. Enlarged. (From Webster. ) in an excited manner and when her antennz come in contact with an aphis she stops very quickly and thrusts her abdomen beneath her thorax and head (see fig. 20), giving the aphis a quick stab—some- times several if the first attempts were unsuccessful; she oftentimes lifts the smaller plant-lice completely from the leaf, they are stabbed so fiercely. The act of oviposition shown in the illustration is not intended to convey the impression that the Aphidius always attacks the grain aphis at this point, as it will stab it from any position; it will oftentimes reach around the margin of a leaf and pierce an aphis on the opposite side. After being stung the aphidids kick up the pos- terior part of the abdomen as though in pain, and sometimes a tiny drop of fluid will appear at the tip of the cornicles. At no stage do _ the aphidids appear to be exempt from attack. The Aphidius readily attacks the winged, but apparently prefers the wingless forms. If parasites are confined with plant-lice for quite a while they will stab them repeatedly, though we have never reared more than one individual from the body of an aphis. It is very probable that in _ eases of this kind it is the survival of the fittest, the strongest Aphidius larva devouring all of the others. The junior author and Mr. W. R. 106 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ Walton, of this bureau, observed a larva, taken from tlie body of a ‘‘oreen bug,’’ to apparently feed upon another larva of the same species that was resting against it. This would seem to indicate a tendency toward cannibalism. The parasites have been observed apparently ovipositing in aphidids that were already dead from parasitic attacks, those killed by fungus, and sometimes even puncturing the leaves of the plants on which Toxoptera were located. The period of oviposition varies from 3 days to a week or more, depending upon the temperature. In warm weather the females will easily live and oviposit for 5 or 6 days. LENGTH OF PERIOD FROM EGG TO ADULT. - Messrs. Kelly and Urbahns found that at Wellington, Kans., from 7 to 15 days are consumed in passing from egg to adult during August and September, while for October and the first week in November it requires from 8 to 24 days. These figures are to a slight degree artificial, as the rearings upon which they are based were conducted indoors. The room was heated by a stove, during the day only, for a part of October and November, and all fire was extin- guished at night, so that the temperature at night probably went almost as low as out of doors, the house being only a small two- room structure. The average for August and September is 11.1 days; the average for October and November (first week) is 19 days, the average for the whole period being 15.9 days. These averages were made up from observations on 116 individuals and are therefore of more value than they would be if made from a few individuals only. At Richmond, Ind., the period from egg to adult out of doors varies from 10 to 14 days during August and September, while Toxoptera that were parasitized during November of 1907 and kept out of doors did not give up adults until the 27th and 28th of March and the 4th of April, 1908, a period of over 4 months. EFFECT OF PARASITISM BY APHIDIUS UPON DEVELOPMENT OF HOST. It has been found, as previously stated, that at no time from birth to and including the adult stage is Toxoptera exempt from attack by Aphidius. It appears that a female Aphidius prefers to oviposit in Toxoptera of the second and third instars. The parasite apparently shows little or no fear of them at this stage, while if she is among a number of adult Toxoptera and they begin to kick up their abdomens, she often hurries away, apparently in alarm. It appears from our observations that Toxoptera stung before the first or second molt will not reach maturity, nor will the developing | parasite become adult, there being apparently insufficent nourish- ment contained in such small individuals. Aphidids parasitized after a. ay Te PARASITE, APHIDIUS TESTACEIPES. 107 the second molt will become adult, but may be either winged or wingless; the wings in such cases often being imperfect. Oftentimes parasitized aphidids reach the third molt, but do not become adult before death, though the parasite reaches maturity, and it is probable that such Toxoptera were parasitized just before casting the second molt. This may also account for some of the small individuals among the parasites. 7 EFFECT OF PARASITISM BY APHIDIUS UPON FECUNDITY OF HOST. Experiments have been conducted with the view of learning the number of young that may be produced after parasitization. This can probably be best illustrated by Table XII. a "OW ="W yimpy =v ‘od ¢ «ee e|\ nase oe ZV eeeces IW eussee Ww estas elewescalsousstlccunsecese * posur A, =" Sev leuveansubeeencunwaceunve in Be eessases *eysuy Pay, esens oh Sena ; Od OF AS al ta Sa MCI 6V enwee ‘Vv eeesenlsevcenleccees reese =* “SRQISOTAL + MOE «allen Fee See ee ane RES me en -*"UBISUT YANO gf ORR A< 5 Hn tne ae 0% IU a) eae ee nee z 1Z 8g er eet I ee ee ee ed dee 0) 0 GR. “SOT ew ee ee ee ee ee ee ee ee a eT "=" pesulM. enenee chasm laheeat! ; | ‘Od 0% ee ee es 6 9LV IV ee ee es ee ee ee ee ee SAAT S © Mae = eo eee eee ee ee | ee ODS ei aa See ‘Od al rd os £ OL LV ed ee | “0D noe pron a ee a 0) patie Sey eee? Sa nee ‘OT Il re ed ene eee 2; PV re es ge 2) 0 alae “0D | eee ene eee TOfr -n eee ee al is ‘Od 8 er ee oe =. Zz i) ses eee Ni ed i er en a id aw eOpe ss 2-00 Cn ee ee ee ee ey ee Opn" weleweee Se SORE ‘OT F ed ee tr ay sees Oe ed i Med J.) eee SA ODs Ce “-*"0p"* ee oe meee! Ji og ‘any |Z Pcs Os (stan wea lem's “2 ny feveeee wasapalscaned|srcuen|a¥letleesvsoness spoduray | 2p caepy [occcctcctececec cette ete eters ““anysuy yyanog, [ones seeey orp aeyy | aeyy f soya | caoye [amy | amyy | aeyy | atyy | cape | 2ey por . . “‘gunod . . * . W . . . Ww . W . WwW . W ” . [ d ‘s]eaprArpuy Ak 4 Wig, yNpe jo pury ee pazyyjseaed U9 OdeI1g jo roquinn, ‘sunod Joquimnu Ape oz “100 | ¢ Ay ESM oe wefereeeel g I go [te tete feces t feces tees stoprr|oct el eee sereeeetoperse feces eeeeeeeee eed 1 "po OL ee ee see eee 4 p p en ee ee es conte! Ltt) “see ia Oe eelewe eee eee eee eee see ee ne ea st ee See eee, ‘Od, 9 ee ee ee il ¢ Zz ee ee SSo] Uy. Sah ADB eee eee ee ee eee ee “4[O pe sso] IM ee ee ae ‘od 6 Ce ee ee ee es | ae ra 9 ‘Vv es ee ee ices fl ee 0 en eee OT "Oo eee ee ee ee et RS ee he On)" * oe re tattle | iad "LO 9 ee ee ee ee ee 9 ~—seaee os sy ease eel ew serene eee “po. UM. cl wo ee ee ee ee eee et ss os"9*TBISUy YQINOW Sas * SPAS ese ay, er ah he Me BOO | Ee ae | ahi bbs eR oa “sunod : : *S[BPTATpuUy sryde 4[npe jo pur -qisered pezpiseied uaa odv)g eb [e}OJ, ps jo pur ec Jo soquinn ‘sunod Joquinu Ape ‘sadvaon) sa) sniprydy fq uoyveyrsnund fo ‘wnuruosb vidoxoy, fo hiyypunsaf uo ‘pafqf— TTX ATAV, i PARASITE, APHIDIUS TESTACEIPES. 109 Two adult Aphidius issued from those individuals included in the first section of the table and 18 from those in the last section. In this latter section Aphidius began to issue March 30 and the last issued on April 3. Those that issued on the latter date were from those that were adult winged adults when parasitized. All of these experiments were conducted indoors, and those of the last division of Table XII, under a daily temperature ranging from 50° to 80° F. From Table XII it will be seen that Toxoptera that have molted only twice before being parasitized may become winged adults, and in some instances produce young. All of our observations show that individuals that have molted three times and then been parasitized will become adult and produce young, and in case they are wingless they may produce 10 or more. Eleven is the maximum number of young, according to our observations, produced by a single individual after parasitization. - MOVEMENT OF LARVA WITHIN THE HOST AND MANNER OF ATTACHING IT TO THE PLANT. Observations were made upon the movements of the larva (fig. 21) within the host by the senior author at Manhattan, Kans., in 1907, and published in the Proceedings of the Entomological Society of Wash- ington.! It appears that the larva of the parasite, at least until after it attains some growth, moves little if at all within the body of the host, and thus interferes with no vital functions of the Toxoptera. When the larva nears maturity, as shown by the yellowish color of the abdomen of the ‘‘green bug,” 1t becomes quite active, making a number of revolutions within the body of its host, at which time the latter seizes the leaf with a rigid death-grip and the last spark of life soon fades. The object of the revolutions is, apparently, to mold the body wall of the aphidid, while it is still plastic, into the most suitable shape for pupation. An idea of how this desired end is accomplished may be obtained by glancing at the accompanying illustrations. Figure 22 shows the normal position of the parasitic larva within the body of the host before the revolutions begin. It-was found that a _ fully developed larva (fig. 23) made three revolutions within the body of the host, always going forward, in the space of 35 minutes. During the next 5 minutes it made another revolution; a fifth revolution was completed in the next 10 minutes; the sixth during the following 8 minutes; the seventh in the next 9 minutes; the eighth after a space of 4 minutes; the ninth in the following 4 minutes, after which, on account of the opaqueness of the walls of the host, no further count was kept of the revolutions, although several more were known to have been made. Some of these different positions of the larva and 1 Proc, Ent. Soc. Wash., vol. 9, Nos. 1-4, pp. 110-114, 1907, THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ At this time, or about one and one-half hours the shapes the body of the Toxoptera assumes are graphically repre- sented in figure 21. 110 (‘IoysqoM UWo1g) ‘wid §ze'zt ye uoryIsog (¢T) ‘wid Ze-ZT 98 UONIsog (FT) “wd LOCI 4S UOTISOg (1) ‘Wd ZZ'ZI ye UOTSOg (ZT) “wud OZZI 4" UONISOg (IT) “we'd C1 ‘ZI ‘eAILT ay} JO UOTORI}UOD SULMOYS ‘UOTJNJOAeI WUT Jo UOT}e[duI00 ye woNIsog (OT) ‘utd [T'ZT ‘UoMN[OAel YIYSIo Jo uoTJe[du100 ye pus SuLINp suOTIISOg (6-8) “SUOLJNTOASI jo[CuI09 sol] spel 41 OUT} YOM SupmMp “ur *e GEIL pus ‘UL ‘Bw TT UseMjoq BAIe] SnIprydy oy} Aq pournsse suoljIsod ay} Joouog (2-z) “we TT ‘adojaauoyednd ev oyurstyde ayy yo Apoq ey} Suruorysey JOY SUOTIN[OASI S}I ZuTUUTseq o10jaq ysnf ‘styde-ureis Sutids ay} Jo a[emoy 4[Npe ssejsutm yo Apo ut sadza9n}89) snapryd p Jo BAIL JO UOTISOg (1) —1Z ‘DI tL i774 after the observations were begun, the body wall of the ‘‘green bug”’ became quite dark and almost globular in form, and this shape it afterwards retained. PARASITE, APHIDIUS TESTACEIPES. lil Mr. Kelly, of this bureau, later took up the observations at this point, during the fall of 1908, and published the results of his obser- ; P, : ‘ q q . Fic. 22.—Pesition of larva of A phidius testaceipes in the body of the spring grain-aphis at the beginning of the change to a yellowish color. Muchenlarged. (Original.) vations in the Proceedings of the Entomological Society of Wash- ington.1 Mr. Kelly confined some aphidids that were nearly dead Fic. 23.—Full-grown larva of Aphidius testaceipes taken from body of thespring grain-aphis as shown in figure 22. Much enlarged. (Original.) from parasite attack on a slide and observed them under the microscope. He found that as the body of the “‘green bug” takes on a brownish tint, the Aphidius larva within makes a longi- tudinal slit or opening in the ventrum and enlarges it until it is more or less oval in shape, as shown in figure 24. The rigid, firm manner in which Tox- optera grasps the object upon which it is resting at death apparently has the effect of holding it in place while the movements of the parasitic larva are going on within. When the opening is complete the larva begins to spin its cocoon, at the same time ejecting a glutinous fluid that makes the strands adhere to any object 1 Proc, Ent. Soc. Wash., vol. 11, No. 2, pp. 64-66, 1909, 112 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ with which they come in contact. The body of the aphidid is cemented firmly to the object upon which it finally comes to rest. The inner abdominal walls of the plant-louse are also lined with silk, which firmly adheres to them, and it may be that the silk also acts as a tanning substance for the body of the aphidid, as the latter be- comes leathery and is apparently impervious to water; the old leathery bodies of the plant- lice may often be found firmly attached to plants after a heavy rain. After the cocoon is completed the larva becomes quiet and in most cases assumes, according to the junior author, a position directly opposite to that which it assumed while feeding and develop- ing. Figure 22 shows a larva feeding, how- ever, in the reversed position; this seems to Fic. 24.—LarvaofAphidiustesta. € Uwnusual, the normal position bemg as ceipes spinningitscocooninthe sShownin Figure 21, l. The larvaoftentimes, a eae on becoming fully developed, is in some way ing in walls of underside of dislodged from the body of the aphidid. pigeaa}* Much enlarged. This is probably due to some interference while attaching the host to the leaf. These cases are quite numerous in badly infested fields and the larve appar- ently never become adult. Figure 25 is a graphic illustration of one of these accidents. Mr. Kelly found that the pupal stage lasted from 3 to 4 days. Fic. 26.—Full-grown larva of Aphidius Fic. 25.—Larvaof A phidiustestaceipes work- testaceipes: a, Lateral view just prior to ingits way prematurely from the body of pupation;b, front view of head. Greatly the spring grain-aphis. (From Webster.) enlarged. (Original.) Figure 26 shows the larva just prior to pupation. These observa- tions were made indoors, during the winter, at the ordinary room temperature. It requires from 3 to 5 hours for the Aphidius to PARASITE, APHIDIUS TESTACEIPES. 113 emerge as an adult after the first movements of the pupa begin, and when ready to issue the pupa expands and contracts the abdomen, moving the feet and antennez until these are freed from their gum- like covering. Upon studying the pupe (fig. 27) closely, we find that the prothorax bears two rows of distinct elevations or tubercles, but we have been unable thus far to ascribe any particular function to them and they disappear with the gum-like covering. The junior author finds that the adult gradually works itself about until it gets in a position with its back to the ventrum of the old aphidid shell, when it cuts a circular hole, as ,,, fe eo described by Mr. Kelly, and crawls out, always Aphidius testaceipes with its head pointing toward the head of the old ee oe aphidid. Figure 28 represents an old dead body of enlarged. (Origi- a “‘oreen bug” after the parasite has issued. = eae ages eo FECUNDITY. From the prompt manner in which Aphidius, under favorable weather conditions, overcomes Toxoptera it will readily be seen that the former must be a very prolific breeder. The average adult female contains from 4 to 450 egos. These eggs are lemon-shaped (see fig. 19), very pale, and translucent. Messrs. Kelly and Urbahns conducted a number of experiments at Wellington, Kans., in 1908, to determine the number of offspring produced by one individual. They found that one Aphidius would parasitize as many as 206 Toxoptera. In their experiments, however, they used only afew more than 200 Toxoptera to each individual. Mr. Parks, at the same place in 1909, conducted 16 experiments, using from 300 to 500 Toxoptera and he had a maxi- mum, in one case, of 301 aphidids parasitized Fic. 28.—Dead “green bugs” irom one individual Aphidius. His minimum (Toroptera graminum), was 3; his next highest number was 33, and Spowing holes from which his next was 44. Of the sixteen, 12 fell below the matured parasites of = gee eee ames 100; his average was 94.6. e to ure shows the lid : still eiciinedt bee pushed Mr. Parks also conducted experiments at the back; the bottom figure same time as the above to ascertain what the ef- shows the parasite emerg- 3 . : ing. Enlarged. (From fects of continuous mating of one male to differ- ee.) ent females would have on the offspring. In this experiment 1 male was mated to 12 unfertilized females within a period of two hours, after which each female was placed in a separate cage with about 100 Toxoptera that had not been exposed to Aphidius. 26675°—Bull. 110—12——8 —pE—, RS one SsR 188 180 1 0 189 180 50 0 190 180 8 9 191 180 26 16 females were not fertilized, as ae Kelly finds that females pre = | inate when the eggs are ee fertilized. Table XIV he this latter point. TaBLe XIV.—Offspring of Aphidius produced from eggs properly oll =A Offspring. Cage No.— Males. Females. 197 39 67 297 15 20 299 13 33 300 24 40 302 20 34 304 16 50 306 47 12 333 115 15 403 26 41 404 38 93 405 26 44 2 Total .. 379 429 1 These two females were apparently unfertilized, although they were supposed to have mated, as’ give about the same results as some of the unmated females. If these two be eliminated it will be seen the females are far in excess of the males. PARTHENOGENESIS. In all of the studies of parthenogenesis care was taken to f ast ar both parents and offspring, the individuals of each family or bre being preserved and kept entirely separate for future syste studies, which were later carried out by Mr. Viereck. The fist record of.parthenogenesis of this species was publis the Proceedings of the Entomological Society of Washington, a junior author, whose attention was first called to this phenom me aay * 1 Proc. Ent. Soc. Wash., vol. 10, Nos. 1-2, September 15, 1908, pp. 11-13. € 2 PARASITE, APHIDIUS TESTACEIPES. 115 during the summer of 1907, while making observations on the life history of the species; hence, a series of experiments was begun in order to learn something definite in regard to it. Seven female Aphidius were selected, just as they issued from their cocoons (being therefore unfertilized), and placed in separate cages with 30 to 40 Toxoptera not previously exposed to parasite attack. All of the parasites began ovipositing at once. After one of the females had apparently parasitized all of the aphidids in her cage she was mated and placed in a second cage with a number of Toxoptera as before. All the offspring from unmated females were males, but the offspring from the single female, after she had mated, comprised 22 females and 4 males. Messrs. Kelly and Urbahns elucidated this phenomenon more fully during the summer of 1908 at Wellington, Kans. These experi- ments were conducted as follows: Starting with a mated female, the females from among her off- spring were isolated, even before emergence. On their appearance they were given Toxoptera not previously exposed to parasitic attack. The few females from among this second generation were again isolated in the same manner, the females in all cases being kept unmated. Nearly 100 experiments were conducted in this manner, but only 48 gave results. The offspring of 44 out of the 48 isolated were, all of them, males. Of the 4 remaining females, the offspring of 3 were as follows: 70 males and 3 females; 101 males and 6 females; 67 males and 1 female. In the case of the remaining female, some uncertainty exists as to whether she had been fertilized or not, and, for this reason, a census of her offspring is not here included. Of the three exceptional cases the offspring from one female were not bred any further; from a second, the offspring became all males in the second generation; the offspring from the third female produced two females in the second generation, all finally becoming males in the third generation. In this manner it will be seen that Messrs. Kelly and Urbahns were able to rear a limited number of females parthenogenetically to the third generation. Beyond this all of the offspring were males. While the conditions under which these experiments were conducted would not obtain under ordinary field conditions where the infestation was great, it could very easily occur where there are very few aphidids present. This apparently abnormal feature, then, would greatly assist the species in tiding over periods of scarcity of plant-lice. HOSTS OF APHIDIUS TESTACEIPES. Since we were able to find Aphidius testaceipes over almost the entire United States, it seemed clear to us that it must have hosts other than Toxoptera graminum. Accordingly Messrs. Kelly and Urbahns con- 1 Ann. Ent. Soc. Amer., vol. 2, No. 2, 1909, pp. 67-87. 116 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ ducted about 200 experiments in order to gain some definite informa- tion on this point. Their mode of procedure was to search out differ- ent species of parasitized aphidids in the fields, rear the adult para- sites, and breed them into Toxoptera graminum; then, if possible, breeding them again into the original host. One attempt, if unsuc- cessful, was not considered sufficient, several trials bemg made. While conducting these experiments, other species of parasites were found that would breed into Toxoptera also. These will be dealt with in their proper places. In all of these breedings, both parent and offspring were kept separate and preserved for future study. It was found that Aphidius testaceipes would breed interchangeably from Toxoptera into Aphis setarix, Aphis maidis, Aphis middletoni Thos.,' Aphis gossypii, and a species of Chaitophorus. Thisis the same as the list published by the senior author in the Annals of the Ento- mological Society of America,? with the exception that Chaitophorus is added and Aphis brassice has been expunged from the list, as it has been learned that the species of parasite that would interchange with Tozoptera graminum and A. brassice is another species of Aphi- dius. Besides the above list of interchangeable breedings, Aphidius testaceipes has been reared from Aphis enothere at Salisbury, N. C., by Mr. R. A. Vickery; from A. medicaginis at Wellington, Kans., by Messrs. Kelly and Urbahns; from A. rumicis at Clemson, S. C., by Mr. G. G. Ainslie; from Macrosiphum viticola at Wellington, Kans., by Mr. Kelly; from M. granaria at Spartanburg, S. C., by Mr. G. G. Ainslie; from Melanozantherium sp. at Leavenworth, Kans., by Mr. Kelly; from Macrosiphum sp. on black gum (Nyssa sylvatica) at Salisbury, S. C., by Mr. Vickery; from Aphis avenz, at Salisbury, N. C., by Mr. Vickery; at Leavenworth, Kans., by Mr. Kelly, and at Washington, D.C., by Mr. C. N. Ainslie; and from Aphis medicaginis by Mr. J. T. Monell, at St. Louis, Mo. Aphidius testaceipes has also been reared from several unidentified species of aphidids, as follows: From an aphidid on Ampelopsis sp. by Mr. C. N. Ainslie; from an aphidid on Capsella sp. at Wellington, Kans., by Mr. C. N. Ainslie; from an aphidid on Kochia scoparia at Rochester, Minn., by Mr. C. N. Ainslie; from an aphidid on locust at Wellington, Kans., by Mr. Kelly; from an aphidid on plum at Salisbury, N. C., by Mr. Vickery; from an aphidid on pigweed (Chenopodium album) in Olmstead County, Minn., by Mr. C. N. Ainslie. Further addition to this list of hosts may be made by citing the hosts of some of the synonyms of Aphidius testaceipes3 We will deal 1 Aphis middletoni can not be satisfactorily separated from Aphis maidi-radicis and when found on any other plant except Erigeron it has usually been identified as Aphis maidi-radicis. (See Bul. 85, Bur. Ent., U. S. Dept. Agr., pp. 113-114. Contributions to a Knowledge of the Corn Root-Aphis, by R. A. Vickery.) 2 Ann. Ent. Soc. Amer., vol. 2, No. 2, pp. 67-87, June, 1909. 3 See Proc. U. S. Nat. Mus., vol. 11, pp. 665-669, 1388. PARASITE, APHIDIUS TESTACEIPES. 117 with these synonyms collectively under A. testaceipes. The hosts then would be as follows: Reared from Macrosiphum cucurbite by the senior author at Lafayette, Ind.; reared from an anphidid on Eragrostis sp., by Mr. D. W. Coquillett; reared from Macrosiphum sp. on Audibertia stochoides, by Mr. Coquillett, at Los Angeles, Cal. Swept from Lragrostis sp. by the senior author at La Fayette, Ind., October 4, 1885; reared from Myzus sp. on Hosackia glabra by Mr. Coquillett at Los Angeles, Cal.; reared from Myzus ribis (currant aphis) by Prof. A. J. Cook, Lansing, Mich.; reared from Aphis gos- sypw by Prof. G. F. Atkinson, Columbia, S. C.; reared from Macro- siphum sp. on Abutilon by Mr. Coquillett at Los Angeles, Cal.; reared from Aphis avene by Mr. J. W. Barlow, June 20, 1882, at Cadet, Mo.; reared from Aphis on peach May, 1886, by Mr. Albert Koebele, Fresno County, Cal.; reared from an aphidid on Baccharis viminalis by Mr. Coquillett at Los Angeles, Cal. There are probably many other hosts besides the ones we have mentioned of which as yet we have no knowledge; and when this situation is taken under consideration it is very easy to see that it would be only in rare instances and under peculiar conditions that a locality would be found where Aphidius testaceipes would not be lurking, waiting for favorable weather conditions and abundant supplies of its host aphidids to make its appearance in greater or less numbers. HIBERNATION. Aphidius is capable of withstanding extreme degrees of cold, as witnessed by the fact that Toxoptera parasitized during November, 1907, at Richmond, Ind., did not give up adults until the 27th and 28th of March and the 4th of April following. During February they were in the larval stage within an old dead body of a Toxoptera. Mr. Kelly found that at Leavenworth, Kans., the parasites hiber- nated as larve and pup. This was shown by the fact that he found Aphidius testacevpes in the field in this condition on November 13, 1907. From a lot of 50 dead parasitized Toxoptera from the same field, that had been washed or rubbed off the leaves of the young grain and were taken out of the mud about the wheat plants on February 28, after the winter was practically over, Mr. Kelly found that 17 contained full-grown larve, 12 contained pupe of a light color, and 21 contained pupe of a dark color; the latter apparently were ready to develop promptly with the advent of warm weather. Mr. Kelly collected, on the same date and also from this same field, a number of Toxoptera in various stages of development that were hibernating in the fields and which showed no signs of parasitism; the weather had been such as to preclude the possibility of their having recently been parasitized. These were placed in a warm room and soon showed evidence of parasitism, Aphidius testaceipes being finally reared from them. 118 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ The junior author found that at Richmond, Ind., the adult Aphid- ius would live for at least two weeks when the temperature was below freezing. The parasites were taken into a warm room several times during these two weeks and they would become active, but when placed out of doors they would soon become numb. These adults were confined, however, so that excessive moisture was excluded, and they may not be able to live for so long a time im the fields unprotected. The fact that Aphidius can during comparatively cold weather | remain for a long period within the body of its host, and the latter give no external visible evidence of its presence, will readily account for the apparent absence of the parasite from any locality for an almost indefinite period; however, when the weather warms up sufficiently for development of the parasite to go on, its presence readily becomes apparent. For these reasons, as well as others that will be men- tioned in their proper places, it is impossible to say, from a cursory examination, that Aphidius is not present. INFLUENCE OF WINDS IN THE DISPERSION OF APHIDIUS TESTACEIPES. As the natural suppression of an outbreak of Toxoptera is more dependent upon the activity of this parasite than of any other of its natural enemies, it is important to learn the extent to which the para- site is able to follow its host in its spread from the South over the country to the northward. Dispersion of Aphidius may be accomplished i in two ways—first, as larve in the bodies of the winged host insect, where it is usually invisible, and, second, by being carried bodily with the winds along with the host. By referring to Table XII on page 108, it will be observed that a number of cases are there recorded where individuals of i BP oirde _ _. Toxoptera graminum which were a tase Ali a pert peng gre; parasitized developed to winged Aare adults, lived for a period of eight or nine days, and during this time gave birth to young, but from their dead bodies Aphidius afterwards issued. The pres- ence of winged parasitized females on the leaves of grain and grasses inhabited by Toxoptera is of common occurrence (see fig. 29). Thus, while it has not been possible to observe the parasitism of individuals and follow out the final dispersion of the same, the evidence tending to show the probability of its general occurrence is so overwhelming that such direct proof does not seem necessary. With the obscurity PARASITE, APHIDIUS TESTACEIPES. 1m AS, relative to this matter cleared away, it will be observed that it is entirely possible for great numbers of the adults, or those that are nearly mature, to become parasitized in a southern locality, the latter to develop to winged females under a more or less high temperature, and for both to be carried many miles to the north- ward, and then settle down and begin to reproduce, the Aphidius becoming adult and issuing later from the dead body of its host. In the meantime the offspring of the host Toxoptera would, of course, develop and themselves reproduce, some of them, without doubt, falling victims to the very parasite brought along by their parent. While this may not be the chief factor in the dispersion of this parasite, it probably enables it to follow along with the host insect and become diffused with it, although if low temperatures prevail after the time the migrating female settles in her new home there may be consider- able delay in the issuing of the adult parasite without to any great extent delaying the development and preventing the increase of Toxoptera. | With the temperature at a point which enables Aphidius to become active there is no doubt that the parasite follows with the host insect, and, indeed, these parasites are usually found on the wing in the com- pany of their hosts during warm sunny days. With high cold winds, which usually come from the northward and would tend to drive the parasites back over territory to which Toxoptera has already come and from which it has now largely disappeared, the adult Aphidius is observed to nestle down among the infested plants and not to venture abroad. Thus it is that this parasite is doubtless usually present in some form in the grain fields with the Toxoptera, though critical examinations of such fields may fail to reveal them until the temperature reaches a point that enables them to become active. All of this is applicable to the insect in southern territory where no ege stage is yet knownto occur. Aphidius occurs all over the coun- try, and we have learned that in the North it winters as fully devel- oped larve and pup within the ‘‘cocooned”’ bodies of its hosts, its emergence and activity in spring being controlled by the temperature and its dispersion influenced by the same forces and in much the same manner as in the South. TEMPERATURE INFLUENCES ON APHIDIUS. ' Probably the whole secret of these disastrous outbreaks of Tox- optera lies in the fact that this parasite is not active in a tempera- ture much below 56° F., while, as has already been shown, the aphis begins to reproduce in a temperature at or slightly below 40° F.— a probable difference of at least 16° F. Therefore the situation in a field of wheat in the South in early spring may be described in this way: There are present many Toxoptera of all ages, with viviparous 120 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ \ reproduction continually going on during mild weather. Aphidius may also be present either as invisible undeveloped overwintering larve within the living bodies of its host, or it may be present as mature larve or pupe in the dead and dried ‘‘cocooned”’ bodies of the same. Besides this, in the light of recent studies of Aphidius by Mr. Viereck, the same may be true with reference to its occurrence in a considerable number of other common species of aphidids, inhabit- ing a great variety of vegetation, in the same neighborhood, upon which this same species of Aphidius is parasitic. Thus, it is per- fectly clear why, with Toxoptera swarming in the fields, and the parasite present, about 10 days, with the temperature ranging from 40° or 50° to 60° or 70° F-., is sufficient to enable the latter summarily to suppress the invasion. The abruptness with which this change is brought about is easily explained by the fact that a parasitized female Toxoptera produces young during only a comparatively few days after being parasitized, although she may survive several days longer, especially if the weather be cool enough to retard the development of the parasite. In the North the situation is usually quite different, as parasites can not begin their work here to any extent until after the eggs have hatched, and the stem mothers and their offspring have appeared in the fields, thereby furnishing host insects. The overwintering of immature Aphidius larve in the bodies of the host is in the North ordinarily precluded by the absence of living host individuals during severe winters, although mature larve may winter in the dead bodies - of the host as in the South. Stem mothers are probably never present in great numbers and considerable time is therefore neces- sarily required for their offspring to become excessively abundant. For this reason parasitism, over the section where the host insects pass the winter in the egg, begins later, and, at the start, proceeds necessarily much slower than in the South, but on the other hand Aphidius, unless the winter be an exceptional one, must of necessity winter over in the ‘‘cocooned’’ bodies of its numerous hosts, as mature larve or pupx, and would therefore promptly respond to the warm days of early spring, although delayed somewhat by low temperatures that might not retard the host insects. There is one point in connection with parasitism by Aphidius that must be always kept in view, particularly to the southward, in order that mistakes and misstatements may be avoided regarding its actual occurrence in any particular locality. While the larva is contained within the still living body of its host its presence there is not easily detected. Indeed it is not until the larva becomes nearly full grown that it can be detected even by an expert. Therefore, in the light of what has previously been stated concerning the situa- tion in milder latitudes, there may be millions of living larve PARASITE, APHIDIUS TESTACEIPES. 121 present for weeks in a field with no visible indication of their presence. Yet only a few warm days are required to bring about their final development, whereupon the presence of the more or less globular, leathery, brown bodies of the parasitized host first begin to attract attention and thus actually reveal the presence of the Aphidius, which has already been established there. An excellent illustration of this is afforded by an occurrence of Toxoptera in eastern North Carolina, observed by Mr. L. M. Smith. In a small field of oats near Newport, wingless viviparous female Toxoptera and young were found in destructive abundance with no indication whatever of the presence of Aphidius. Yet when speci- mens of the pest submitted by Mr. Smith reached Washington, some of them were beginning to change color from the presence of Aphidius larve within their abdomens. Again, when Mr. C. N. Ainslie visited Wellington, Kans., April 1, 1907, he observed no trace of the presence of Aphidius, but upon returning to this same locality on April 10 he found them present. Only a few of the Toxoptera had yet become dark brown, but a large number showed the orange color that told the story of their parasitism. Therefore all statements made in previous publications relative to the lack of parasites, or to the extent to which they occurred in any field or locality, must be under- stood as applying only to either the adults or to the browned cocooned bodies of the host insects, and are not in any sense to be considered as indicating the extent to which these host insects were carrying obscured Aphidius larve about with them in their bodies to develop adults whenever there were a few sufficiently warm days. EFFECTS OF WET WEATHER ON THE DIFFUSION OF APHIDIUS. There is another element affecting the diffusion of this most efficient of natural enemies of Toxoptera, namely, protracted rains. When it is raining the parasite simply will not take wing at all or move about in a way to be affected by winds. This element will not admit of tabulation for the reason that a thunder shower followed by warm, bright sunshine tends to make these, as well as all winged insects, more active after the storm has passed. Thus, the amount of precipitation really means little, while a slow, drizzling, protracted rain (though the total precipitation may be much less) will keep the parasite in seclusion much more effectively. Hence it is that not only a comparatively high temperature accompanied by winds is essential, but the weather must also be fair and sunny. In British East Africa Toxoptera is worse during seasons when there is much wet weather, and in the Orange Free State outbreaks of the pest seem to be also associated with similar meteorological conditions during spring. 122 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’’ Other Species of Aphidius. Aphids confusus Ashm. has been-reared from. Toxoptera from different parts of the country, including the Department of Agri- culture grounds in Washington, but to what extent it assisted in overcoming Toxoptera in 1907 is not altogether clear. Its life history is apparently similar to that of A. testaceipes Cress., and its effect upon the aphides is apparently the same. Aphidius avenaphis Fitch was reared from Tozoptera graminum in the insectary at the Department of Agriculture in Washington, the host insect having been parasitized, under observation, by adult virgin Aphidius reared from Aphis sp. Fic. 30.—Aphelinus mali, a parasite of the spring grain-aphis. Greatly enlarged. a, Stigmal club, much more enlarged. (Original.) Species of Aphidius, apparently undescribed, were sent to the bureau from Njoro, British East Africa, and the Orange Free State, South Africa, as enemies of Toxoptera graminum in that country. Aphelinus. We have reared three species of Aphelinus from Tozoptera grami- num; Aphelinus malt Hald., A. nigritus How., and A. semiflavus How. Aphelinus malt Hald. (fig. 30) was reared from Toxoptera at Lafayette, Ind., in 1885 by the senior author, by Mr. R. A. Vickery at Richmond, Ind., and from the same species at Clemson, S. C., by Mr. G. G. Ainslie. Messrs. Kelly, Urbahns, and Parks reared it from Aphis setariz Thos. at Wellington, Kans. Messrs. Kelly and Urbahns also reared it from Schizoneura americana Riley at Wellington. Mr. Vickery reared it from Schizoneura lanigera Haussm. at Richmond, PARASITES, APHELINUS. 123 Ind., and from Oolopha eragrostidis Middl. at Mt. Vernon, Ind. Mr. Kelly reared it from Pemphigus fraxinifolit Riley and from an aphidid taken on Panicum sp. Mr. C. N. Ainslie reared it from Macrosiphum rose Linn., at Mesilla Park, N. Mex. This species has been previously reared, as stated by Dr. L. O. Howard! from Schizoneura lanigera Haussm., Colopha eragrostidis Middl., Aphis brassice Linn., Pemphigus fraxinifoli Riley, Aphis monardz Oestl., Macrosiphum rose Linn., Aphis sacchari Zehnitn., and Tetraneura colophoidea. Aphelinus nigritus How. (fig. 31) was first reared from Toxoptera at Spartanburg and Clemson, 8. C., by Mr. G. G. Ainslie. It was Fig. 31.—A phelinus nigritus, a parasite of the spring grain-aphis. Greatly enlarged. a, Stigmal club, still more enlarged. (Original.) reared from the same species of aphidid by Mr. C. N. Ainslie at Springer and Mesilla Park, N. Mex., and St. Anthony Park, Minn. Mr. T. H. Parks reared it from Toxoptera at Wellington, Kans., and Messrs. Kelly and Urbahns reared it from Aphis setariex Thos. at Wellington. Aphelinus semiflavus How. (fig. 32) was first reared from Myzus persice Sulz. and Chaitophorus viminalis Monell by Prof. C. P. Gil- lette at Fort Collins, Colo., in 1908. It was later reared by Mr. G. G. Ainslie from Toxoptera at St. Anthony Park, Minn., and from a black aphidid on bluegrass (probably Rhopalosiphum pox Gill.) at Mesilla Park, N. Mex., by C. N. Ainslie. 1 Ent. News., vol. 19, no. 8, pp. 365-366, 1908. 124 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ NOTES ON LIFE HISTORY AND HABITS OF APHELINTUS. Mr. C. N. Aimshe made some observations on A phelinus nigritus at Mesilla Park, N. Mex., in 1908. He states that when the adult is ready to oviposit it approaches an aphidid very slowly and cautiously, moving or swaying its body slightly from side to side and waving its antenne. When the antennz finally touch the plant-louse it stops, turns suddenly about, moves backward slightly, and then gives the victim a thrust with its hairlike ovipositor. This operation appar- ently causes pain to the aphidid, as she begins to “kick up” her abdomen and there sometimes appears a tiny drop of fluid where the puncture was made. iy, i i yt eee \\) Fic. 33.—Dried remains of body of the spring grain- aphis from which adult Apheiinus igritus has emerged. Enlarged. (Original ) fi | { J Fic.32.— 5 spring grain-aphis. a, single day to satisfy its hunger. The average ivy. 3} anterior ex. number per meal was at least 50, and we may tremity protruded, assume that 6 times this number were taken per ‘“Nowins Preastbone; ¢, ; ‘ Ria ventral view of poste- day. On this basis the number of aphidids de- rior segment. a, Much stroyed by birds on the farm daily during the age HL migration season is 90,000. Below is a partial list of the species Mr. McAtee found devouring Toxoptera at Winston-Salem. A complete list can not be given at this time, since his studies are not yet finished; many species will undoubtedly be added. Goldfinch (Astragalinus tristis). Vesper sparrow (Powcetes gramineus). Savanna sparrow (Passerculus sandwichensis savanna). Chipping sparrow (Spizella socialis). Song sparrow (Melospiza melodia). All of these birds occur over the entire South. MISCELLANEOUS ENEMIES OF TOXOPTERA, Under the head of miscellaneous enemies may be considered ene- mies that are of very slight economic importance; those, in other words, that have been observed occasionally attacking Toxoptera. 136 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ In 1890 the senior author, at Lafayette, Ind., found that the young of the snowy tree-cricket (Z’canthus nweus De G.) were very fond of Toxoptera and fed upon them freely. Mr. A. N. Caudell, of this bureau, observed one of the soldier bugs, Reduviolus ferus L., attacking Toxoptera on the grounds of the De- partment of Agriculture at Washington in 1908. During the same year Mr. C. N. Ainslie found a larva of a species of the ladybird genus Scymnus at Mesilla Park, N. Mex., attacking Toxoptera, and he seems to think that numbers are devoured by this insect. In 1909, at Washington, D. C., Mr. R. A. Vickery reared the braconid Lipolexis piceus Cress. in limited numbers from Toxoptera. The junior author has at times found a fungous disease attacking the aphidids in his rearing cages, but we have never noted this in the fields. ANTS AND THEIR RELATION TO TOXOPTERA. So far as our observations go Toxoptera is not so attractive to ants as are many other species of plant-lice. We have often found various species of ants in attendance on Toxoptera, but the relations did not appear to be mutually beneficial, the ants nearly always gaining the most by such partnerships. At Hooker, Okla., in 1907, the junior author found ant burrows beside plants in an area badly infested with Toxoptera. In this case some burrows were found where the aphidids were slightly below ground on plants in these burrows, the ants being busy about the aphidids, stroking them with their antenne. Mr. C. N. Ainslie many times observed ants stroking Toxoptera with their antenne. We have found no instances, however, in which ants care for the eggs of Toxop- tera in winter, and Toxoptera does not appear to excrete so much honeydew as do some other aphidids. This probably accounts for the fact that they are not so popular with the ants as are certain other aphidids. In Texas, during 1909, Mr. T. D. Urbahns found ants busily caring for Toxoptera in his rearing cages. He also noted that the ants al- ways attacked the parasite of Toxoptera (Aphidius sp.) whenever they came in contact with it, tearing the larve out of the old dead bodies of Toxoptera and destroying them. REMEDIAL AND PREVENTIVE MEASURES. With an outbreak of this pest fully established, and the winged adults being carried by the winds and scattered over the fields, there to settle down and reproduce, the difficulties in the way of control are quite insurmountable. FIELD EXPERIMENTS. The brush-drag experiments that were carried out under the direc- tion of the junior author at Hobart, Okla. (see Plate IX, fig. 1), have’ not, with the trials we have given the brush drag, proved satisfactory, although Mr. Thos. J. Anderson, Government entomologist of British A i a Bul. 110, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IX. Fi@. 1.—BRUSH DRAG USED BY THE JUNIOR AUTHOR IN EXPERIMENTS AND ALSO BY FARMERS IN DESTROYING THE SPRING GRAIN-APHIS IN THE FiELDS AT HOBART, OKLA. (ORIGINAL. ) Fia. 2.—ROLLER USED IN EXPERIMENTS BY JUNIOR AUTHOR AND BY FARMERS IN DESTROYING THE SPRING GRAIN-APHIS IN OKLAHOMA. (ORIGINAL.) REMEDIAL AND PREVENTIVE MEASURES. \ ea East Africa, states that it is with them the most effective measure at their command for destroying the ‘‘green fly” in wheat fields. With us it was used after the aphidid had fully established itself and was literally swarming over the growing grain. Earlier, at the commence- ment of an outbreak, the effect of its use might prove more satisfactory. Similar experiments were carried out with a heavy roller, such as is generally used among farmers for crushing clods in fields and com- pacting the ground. (See Pl. IX, fig. 2). In this case the ‘results were even less satisfactory than with the brush drag, because the roller acted only on the clods and other inequalities in the surface of the ground. Where the wheat had been drilled the effect on the Tox- optera was less decisive than where the grain had been sown broad- cast. The wheat plants grow in the narrow furrows or grooves and the insects that were displaced dropped down about the plants and the passing roller struck only the ridges, leaving the insects practically untouched. Where the invasion is not chiefly from outside the field itself, and the pest makes its first appearance in spots, management is less dificult. By plowing under these infested spots and immediately harrowing and rolling them further damage may be effectually pre- vented. The junior author had an opportunity to test this measure in western Oklahoma. Covering these spots with straw, where easily obtainable, and burning, is equally effective, but where this last measure was applied by farmers in Oklahoma in 1907 the fields were so completely overrun from the outside that the good effects were entirely obliterated. As between these two methods of suppression, it must be borne in mind that while the seriously affected spots in a field are very small, _asingle load of straw will suffice to cover a number of them, prepara- tory to burning, but after these areas become enlarged it is much more practicable to plow them under. Besides the above-mentioned methods of control, experiments were conducted with different kinds of spray materials. In all of our control methods we endeavored to place ourselves in the position of the farmer, and to use such apparatus as could be obtained locally. Accordingly the junior author, upon reaching Hobart, Okla., the first week in April, 1907, prepared to begin some spraying experi- ments. The only spray apparatus that could be found in the town was a knapsack pump. As stated above, since an outbreak of Toxoptera starts in small areas, where the infestation originates within the field, it was thought possible to accomplish something by spraying these areas. As the infestation at Hobart seemed to be quite general, apparently originating from migrations from farther south and east, the small pump was found to be utterly useless. From here the junior author proceeded to Kingfisher, Okla., where there were clearly defined areas of infestation, and, together with ce 1388 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ Mr. C. N. Ainslie, began experiments with a barrel pump, loaned by a market gardener. One plat was sprayed with 5 per cent kerosene emulsion; another with 10 per cent kerosene emulsion; a third plat with ordinary hard soap, 1 pound to 4 gallons of water; a fourth plat with whale-oil soap, 1 pound to 6 gallons of water. The spraying was done carefully, so as to reach every aphis possible. Upon examination the next day it was found that the 10 per cent emulsion and the hard soap had injured the plants. Not more than 50 per cent of the plant-lice were killed in any of the experiments. On the 15th of April the sprayings were repeated with similar results. All of the aphidids could not be reached, no matter how thoroughly the spraying was done. It was quite evident that unless the ground was almost soaked there would be little or no relief. These spray- ings cost at the rate of about $4 per acre. During the latter part of July it was found that Toxoptera was very abundant on the lawns of the Department of Agriculture at Washington, D. C. This outbreak became known to Mr. E. M. Byrnes, Superintendent of Experimental Gardens and Grounds, who at once had the entire infested block sprayed with a solution of one-half gill of blackleaf tobacco extract to each gallon of weak soapsuds. The application was, however, ineffective. Four days later a strip through this plat was thoroughly saturated with a strong solution of barnyard manure, made by soaking the manure in water. While there was no evidence that this killed any of the ‘“oreen bugs,” after nine days the pest was visibly less on this area than where the application of manure solution was not made. A series of experiments was then undertaken under the senior author’s direction by Mr. E. O. G. Kelly, as follows: Tobacco dust was applied at rates of one-fourth, one-half, and 1 pound to each 100 square feet, but after over a week had elapsed from the date of application no effect was to be observed and no dead insects were found. Kerosene emulsion was applied at 8 and 10 per-cent strengths, and at the end of nine days no “ green bugs”’ were to be found on the areas so treated. Also there was no perceivable injury to the grass. Whale-oil soap solutions, varying in strength from one-fourth of a pound to 2 pounds of soap to each 5 gallons of water, were applied to similar areas. In this case the stronger solution injured the grass slightly, but not permanently; in the case of the lesser strengths there was no injury to the grass whatever. The effect on the “green bug”? was the same in every case. They were not only literally exterminated over the areas treated, but the applications seemed to protect from a reinfestation, in case of even the weakest solution. An examination five days after the application was made revealed the ‘“‘oreen bugs’’ in myriads and breeding freely on the untreated space, while only 8 inches away and on the treated area living bugs were REMEDIAL AND PREVENTIVE MEASURES. 139 scarcely to be found, although the dead bugs were to be observed almost as abundantly as were the living on the space untreated. It must be remembered, however, that these experiments were carried out in grass kept closely cropped by frequent use of the lawn mower, and such areas can be sprayed much more effectively than a wheat field, where the ground would have to be literally soaked in order to reach all of the aphidids. In the light of these experiments field spraying seems an impracti- cal measure, even when small areas are involved. Burning or plow- ing would probably be more effective and the recommendations would probably be more readily complied with, as the average farmer does not usually have spray pumps of any description. Lime and sulphur was dusted on the plants in badly infested areas ‘with practically no benefits. CULTURAL METHODS. Examination of a large number of fields infested by Toxoptera, extending over a wide range of country, resulted in securing a con- siderable mass of information that may be included under the head of cultural methods. The senior author visited Sumter, S. C., April 17, 1907, driving over much of the country in that vicinity. All fields of fall-sown oats, the only grain grown, were infested, there being no perceivable difference in severity of attack between fields following cotton, those following oats, and those on new ground, thus showing that - the pest had swept over the country, diffusing itself generally. At Winston-Salem, N.C., April 19-20, where both wheat and fall oats were grown, the ravages of the pest were much more serious, and fall-sown oats were completely ruimed. A part of one field that had been in oats the previous year had, that fall, thrown up a heavy growth of volunteer grain, while the remaining portion was free of this growth. Wheat was drilled directly across both these areas on November 15, 1906, the whole field having first been pre- pared by disking, leaving much of this volunteer grain undisturbed. April 20, 1907, when examined by the senior author, the wheat on the part that had been overgrown with volunteer oats the previous fall was totally ruined, while on the clean part the damage was about 50 per cent. In wheat fields generally there was a marked difference in severity of attack as between those seeded before and those sown after about November 1, 1906, the later-sown suffering little while that sown earlier, on ground where there was much volunteer wheat or oats, was seriously damaged. This indicated that the trouble had been aggravated by the volunteer growth at the time of wheat seeding the previous autumn. It was very significant that in late- sown fields on clean ground the injury was comparatively small. In Oklahoma it was observed by both the junior author and Mr. C. N. Ainslie that late-sown and pastured fields were destroyed much 140 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’ more quickly and completely than earlier sown, unpastured fields. But it must be remembered that here the almost universal destruc- tion was caused principally by Toxoptera drifting in from outside sources. One feature of attack by Toxoptera has been especially noticeable throughout most portions of the country seriously ravaged by the pest, particularly where only wingless viviparous females have been found. In such fields the destruction was confined to circular areas which constantly increased in size as the season advanced, so long as meteorological conditions favorable to the increase of the pest pre- vailed; unless, in the meantime, the entire field had become overrun from the swarms drifting in from without. The occurrence of these spots (see Plate I, fig. 2) in the fields, while general, is not universal. For instance, the senior author did not observe them in the fields of fall-sown oats in South Carolina, in April, 1907, but he did find them about Winston-Salem, N. C., a day or two later. At Summers, Ark., Mr. C. N. Ainslie, observed a field of wheat, March 18, 1907, where a rectangular strip at one end had been totally killed out by Toxoptera, and learned from the owner that this area exactly corre- sponded with that of a small patch of oats which the previous year had failed to produce more than a very poor crop and had been plowed under without cutting. In preparing the ground for wheat in the fall of 1906, a volunteer growth of oats was reported to have sprung up on this area after plowing. Again the same observer, a little later in the season, found that the regularity of the occurrence of these spots in rows across a field, in northern Oklahoma, exactly corresponded to the location in this same field the previous summer of oat shocks, which had been allowed to stand out through a period of wet weather; the volunteer grain having sprung up there later m the season and remained growing amongst the young wheat in the fall. In Texas the relation of this volunteer growth in the fields, in autumn and early winter, to the abundance of Toxoptera does not appear to differ materially from what is known to occur elsewhere. When the secretary of the Texas Grain Dealers’ Association first appealed to the Government for aid in investigating the pest, particu- lar attention was directed to the possibility that methods might be devised for its control by spraying or otherwise treating the spots in grain fields, for the purpose of checking its ravages before these infested spots had increased in size and before the pest had spread from them over the entire field. Thus it will be seen that primarily infestation is first invited by the volunteer growth starting up in cultivated fields in autumn. If such fields are sown to wheat or oats in the fall, the pest spreads from this earlier growth to the younger and more tender grain. This will of itself suggest several entirely practical cultural methods likely to restrict and prevent the development of the pestin thefields in autumn. REMEDIAL AND PREVENTIVE MEASURES. 141 _ Crop rotation could scarcely fail of giving beneficial results. The destruction of all volunteer grain springing up in fields from which grain has been removed at thrashing gives promise of the greatest relief. Indeed, if careful attention were given to all fields in autumn, and all of this volunteer growth were destroyed before any grain whatever was sown, it is doubtful if such serious ravages as have occurred in the past could be repeated. This can all be accomplished by close: pasturing and careful late plowing, followed as soon as possible by seeding. At Hooker, Okla., the junior author found affected spots both on land that had been devoted to oats the previous year and on land that had previously grown cowpeas. ‘This, as well as some other observa- tions made by other parties, indicates that some of the grasses will have the same effect in inviting attack as volunteer grain growing up in the fields in the fall. It is therefore most urgently recommended, and especially for the South, that all of this volunteer growth of whatever nature be com- pletely killed out in the fields before seeding the following crop. Not only will this mode of procedure benefit especially the southern erain grower, but in the light of our present knowledge of the pest, it will serve as a protection to the spring oats crop over a large area of country where it is doubtful if serious ravages would occur at all were there not myriads of the pest continually developing to the South and drifting northward in spring with the advance of the season. Following along the same line, attention should be directed to the probability that late seeding may prove a preventive of attack, for the reason that the pest will obviously gain less of a foothold in a late-sown field than it will where there has been an early growth of young grain plants. In other words, there is a likelihood that the pest may break out in spots, as has been several times previously noted, and to this extent late seeding is an advantage. However, this would be a serious disadvantage if the fields should afterward be overrun by hordes of migratory winged viviparous females in spring, for in this case the earlier sown and therefore the older and less succu- lent growth would suffer least from their attack. This is shown by the fact that late-sown and winter-pastured fields in Oklahoma suffered most in 1907. It must also be noted that at Winston-Salem, N. C., in April 1, 1907, wheat that had been sown about or a little prior to November 15, on ground free from young growth of volunteer grain, or the grasses, was practically uninfested even though located in the immediate vicinity of other badly infested fields sown earlier on ground more or less foul with young growth. All of this indicates pretty clearly that if all volunteer growth were eliminated in the fall, and the grain sown late, the pest would not become destructive. Of course the amount of benefit secured will depend upon the uniformity with which this method is carried into effect in any locality. 142 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.’’ Over the northern part of the country where the insect passes the winter largely or wholly in the egg state, another measure can be applied to great advantage. The junior author has found that blue grass (Poa) is not only asummer food plant, but that it is very largely upon this grass that the eggs are deposited in the fall, and from which the offspring of the stem mothers make their way to the grain fields in spring. He has observed cases where the portion of a grain field bordered by bluegrass was the most seriously affected part of the entire field. If, then, roadsides, fence corners, and other waste lands were closely grazed in fall, winter, or early spring, these eggs would be largely destroyed and the food supply of the stem mother and her progeny cut off. This can always best be done during mild winters on account of a lack of snow. Where close pasturing is not practicable, burning over during the same season will have a similar if not an even more drastic effect. ARTIFICIAL INTRODUCTION OF PARASITES. As Aphidis testaceipes destroyed such hordes of Toxoptera in apparently very short periods of time, after they had once become established, we thought it possible materially to aid in this destruc- tion by introducing the parasites artifically into localities where they were apparently absent. As Mr. C. N. Ainslie was unable to find any evidence of parasitization in the fields about Wellington, Kans., on April 1, 1907, it was decided to begin operations there. Accord- ingly, on April 9, over a bushel of wheat leaves that were almost covered with parasitized Toxoptera were collected at Kingfisher, Okla. Mr. Ainslie took charge of this material, and on April 10, made a careful survey of the fields about Wellington, Kans., to determine the situation relative to Toxoptera infestation, and on the morning of April 11 he scattered a portion of this material in one of. the most badly infested fields that could be found in that vicinity, the remain- der being left sheltered by the box lids. At this time he could find parasitized Toxoptera already in the fields, both the dead leathery bodies and those showing the characteristic yellow color. The parasites included in this introduction were roughly estimated at 2,500,000; this number, however, was probably not a ‘‘drop in the bucket” tothose alreadyinthefield. Ifthere were only one or two para- sitized Toxoptera to a leaf, when a whole field is considered 2,500,000 would seem to be a very small number. So far as published records show this was the first artificial introduction of parasites into Kansas. April 12 another lot of parasitized material, sent Mr. Ainslie by the junior author from Kingfisher, which was fully as large as the previous consignment, was introduced into another field 2 miles from the first. All of this material, originally intended for one field, was reported as one experiment by the junior author and appeared as one experiment in Circular 93, since Mr. Ainslie’s notes were not on file in the office at the time. We find, however, that Mr. Ainslie, ARTIFICIAL INTRODUCTION OF PARASITES. 143 on his own initiative, conducted two separate experiments, thus rendering the results twice as valuable. April 18 a minor introduction of parasites was made at McPherson, -Kans., and on April 21 there was another similar one at Sterling, Kans. Parasitized ‘‘green bugs’’ were observed present at each place on these dates. Mr. Ainslie remained in the vicinity of Wellington, and more briefly at McPherson and Sterling, for the purpose of making accurate obser- vations on the effect of these introductions. Two weeks later, on visiting the two fields at Wellington, where the first introduction had been made, Mr. Ainslie found that on account of the cold weather the effect upon the parasites was almost the same as though they had been kept in cold storage. Some of those sheltered by the box lids had issued, but had apparently not ventured far from their shelter and were found in a semitorpid condi- tion capable of little movement. The percentage of parasitism from Aphidius appeared to be the same in all other fields in this locality, irrespective of these introductions, except close about the box lids, where they seemed a little more numerous, the conditions of para- sitization generally being about the same as had existed two weeks previous. The Toxoptera, however, had greatly increased in num- bers, and the fields were now plainly showing the effects of their work. Subsequent examinations of fields at Wellington showed that after the weather warmed up in May the parasites speedily overcame the Toxoptera and that the fields where these artificial introductions were made had suffered as much as any fields in the neighborhood from attack by the ‘‘green bug.’”’ All of this seems to indicate that no noticeable good resulted from these introductions, which, in the light of our present knowledge, is not at all surprising. The minor experiment at McPherson was also reported upon to us by Mr. W. Knaus, and his report was in accord with our own observations. On May 17 an artificial introduction of parasites was begun at Manhattan, Kans. While this experiment bore out our former observations, the results obtained here should not bear as much weight as the earlier introductions, since the Toxoptera was already nearly overcome when the introduction was begun. When one stops to consider the numerous and varied hosts of Aphidius testaceipes, its manner of hibernation, its wide distribution, and the higher temperature required for its development over and above that needed by its host; also the fact that it may readily be transported along with its host as adults, or within the body of the latter, one can readily see the futility of attempting materially to increase its numbers or efficiency by artificial introduction into grain fields. 1 Cir. 93, Bur. Ent. U. S. Dept. Agr., pp. 10-12, Aug. 22, 1907; Cir. 93, revised, Bur. Ent., U.S. Dept. - Agr., pp. 12-13, June 23, 1909. 144 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’ ‘LITERATURE CONSULTED. AupricH, J. M.—Catalogue of North American Diptera. AupricH, J. M.—Cultivator and Country Gentleman, vol. 47. p. 498, June, 1882. AsHMEAD, Wa. H.—Proc. U. 8. Nat. Mus., vol. 11, 1888. Brro, Lasos.—Rovartani Lapok, vol. 2, p. 127, 1885. Bucxton, G. B.—British Aphides, vol. 1, p. 80. Bucxton, G. 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Lecartton, A.—Recherches sur le développement embryonnaire de quelques Chrysomélides. Archives D’Anatomie Microscopique, tome 2, 1898. Maccutati, Lure1.—Bol. Soc. Ent. Ital., vol. 14, p. 246, 1882. Manns, Tuos. F.—Bul. 210, Ohio Agr. Exp. Sta., 1909. MaxweEti-Lerroy, H.—Agricultural Journal of India, vol. 3, pt. 3, pp. 243-244, 1908. Mazzanti, Dr. Dom Lute1.—Nuov. Ann. Sci. Nat. Bologna, ser. 3, vol. 6, pp. 342- 352, 1852. PAssERINI, GlovanNnI.—Gli afidi (pamphlet), p. 25, 1860. PERGANDE, THEO.—Bul. 38, Div. Ent., U. S. Dept. Agr., pp. 7-19, 1902. Puitures, W. J.—Proc. Ent. Soc. Wash., vol. 10, nos. 1-2, pp. 11-13, 1908. . Ritey, C. V.—Rept. U. S. Dept. Agr. for 1889. Ritey, C. V., and Howarp, L. O.—Insect Life, vol. 3, pp. 73-76, 1890. RonpDANI, Camitto.—Nuoy. Ann. Sci. Nat. Bologna, ser. 2, vols. 8, 9, 1847. RonpAntI, Camitto.—Nuov. Ann. Sci. Nat. Bologna, ser. 3, vol. 6 (2), pp. 9-12, 1852. Saso, Kart.—Zeitschr. f. Pflanzenkrankheiten, vol. 4, p. 4, 1894. Saso, Kart.—Prometheus, vol. 1, 1889 (1890). ScHOUTEDEN, H.—Mem. Soc. Ent. Belg., vol. 12, p. 231, 1906. SeTreRMAN, G. W.—Colman’s Rural World, vol. 53, p. 193, 1890. Sraut, J. M.—Country Gentleman, vol. 55, p. 639, 1890. -TANNREUTHER, G. W.—History of the germ cells and early embryology of certain aphids. Zoologische Jahrbucher, Band 24, Heit 4, 1907. WasHbsurn, F. L.—Can. Ent., vol. 40, pp. 53-54, February, 1908. WasuBurn, F. L.—Special Report of the State Entomologist of Minnesota, March 1, 1908. Wasusurn, F. L.—Weather Crop Bul. Mo. State Bd. Agr., 1890. Wesster, F. M.—Insect Life, vol. 4, pp. 245-248, 1892. Wesster, F. M.—Cir. 93, Bur. Ent., U. 8. Dept. Agr., 1907. Wesster, F. M.—Cir. 93, revised, Bur. Ent., U. S. Dept. Agr., 1909. Wesster, F. M.—Proc. Ent. Soc. Wash., vol. 9, pp. 110-114, 1907. Wesster, F. M.—Ann. Ent. Soc. Amer., vol. 2, no. 2, pp. 67-87, 1909. WEED, C. M.—Ohio Farmer, vol. 78, no. 3, p. 33, July 19, 1890. Waite, GiLBerT.—Natural history and antiquities of Selbourne, pp. 365-366, 1836. Wu, Lupwic.—Entwicklungsgeschichte der viviparen Aphiden. Zool. Jahrb. Abth. f. Anat., Bd. 3, pp. 201-286, 1888. Wirtaczit, Em.—Entwicklungsgeschichte der Aphiden. Zeitschr. f. Wiss. Zool., Bd. 40, 1884. —————— = INDEX. Page. _emasnad plant of Macrosiphum sp......--...-------------2-+c-+---0- 117, 125 Adalia flavomaculata, enemy of spring grain-aphis................-..-...----- 18, 129 Agropyron occidentale, food plant of spring grain-aphis in America... -.. 32, 41, 42, 43 repens, food plant of spring grain-aphis in America. ---.. A Ce! 42, 43 Ni@iOpe soo nlc seek See 41, 43 ___tenerum, food plant of spring grain-aphis in America.....-.-....--.. 42,43 Alfalfa. (See Medicago sativa.) Allograpta obliqua, enemy of Macrostphum granaria........------------------ 132 probable enemy of spring grain-aphis.................----- 132 Ie on ee ae a eas eth So 128 in bluegrass infested by spring grain-aphis at Washington, D.C. . 37 secondary parasite of spring grain-aphis.........--..----..------ 128 Alopecurus geniculatus, food plant of spring grain-aphis in America..........-- 41, 43 ee a rood plant.ol aphidid._..--...2..225..--...---+-----2------ 116, 125 Andropogon hirtus, food plant of Toxoptera graminum in Africa.........------ 43 Andropogon sp. (See Sorghum.) EEE EP INOS SD... 12. nese gee 2 ke i - oe nner e eee eee sndoe 136 SARANDON ce ce a i i oe Se 136 a a a a ww oS a woh a ee ~ 122, 125 Patasive of spre praim-aphis.........--...-.------- 103, 122-123, 125 mens. late history and habits, notes............-...-------------- 124 petit NUE CAE ek PILES SOME a Sa ne a oe ee se as ce 125 spring pratn-apliis....--~-- . eee 136 probable host of Alloiria sp. - .-. ~~ - - 522 225. 4 222-2 Jee 128 _ Aphidencyrtus aphidiphagus.......-.....-.---+- 126 Megorismus Sp... ~~ 0+ -7:. onc... eee 126 Pachyneuron sp-....-------------:=.3255eeeeeee 127 testaceipes, artificial introduction against spring grain-aphis, futility. 142-143 ; description «.. .\. 2: <..-¢ 28 2e6 - Sao oo 104-105 dispersion, effect of wet weather thereon........-...----- 121 influence of winds thereon.-....-..-..------ 118-119 effect of parasitism upon development of host........... 106-107 fecundity of host... -.. 2S8ee8 107-109 fecundity 2: ...2 52. 32s e2 eA ee 113-114 hibernation... 22 -..- 5 .-5.005..52. 2.22 ee 117-118 hosts... 3.0 oS api Pte eee ee ae 115-117, 125 identity...-3. 2222.22. Le StS ee 104-105 larva, movement within host and manner of attaching it to plant... -. er 109-113 life hhistory.. --.----.---- -- 2 55-- 4254 <2 105-118 OvIposilion..--.--- =. 2s ss eo a 105-106 parasite of spring grain-aphis........--..------- 40, 103, 104-121 parthenogenesis. ......-.- =.= =- ~- == - <4. =< 114-115 period from egg fo adult.........-...--...._2=5=e eee 106 SYNONYMS. .......--2---- -2 2-2-2. -- = 104 temperature influences. ...:..-.2:.-.-.-.--2. > oe 119-121 undescribed species, parasite of Toxoptera graminum in Africa...-.-- 122 Aphidoletes sp., enemy of Myzus persicx...... 2. .:-------=-..--<-- - 133 spring prain-aphis..__._.....2......5.-.00=ee 133-134 Aphis avenzx, Allotria sp. a secondary parasite...........--...-------+------2- 128 host of Aphuhus testacerpes-...-. 2-2... =... ..222. 22 ee 116, 117, 125 prey of birds. -......::.-.-..--2.02.. 5.22. 2 135 Eupeodes volucris . .. 0... -...-.-~=---- 7s 4220 brassicz, Alloiria sp. a secondary parasite._......../.-...---2 235 128 A phidencyrtus aphidiphagus a secondary parasite.........------ 127 host of Aphelhinus malt: .. 2... -2- 2222. -.- $15 ee 123, 125 Aphidius other than Aphidius testaceipes.......-..----.- 116 Megorismus sp. a secondary parasite...........----------..-2- 126 currant. (See Myzus ribis.) gossypii, Allotria sp. a secondary parasite..............---------------- 128 » host of Aphidtus teslaceipes: .-.._- 2. ---.---. 2. eee 116, 117, 125 Pachyneuron sp. a secondary parasite . . ...-.---.---------+--- 127 (?), host of Aphehnus semiflavus.-........--.----:-... 125 graminum= Toxoptera graminum......-..------------------+------seeee 1% maidi-radicis, host of Aphidius testaceipes............------------------ 125 males, females, and eggs in North Carolina............-.--- 47 moaidis, host of Aphelinus semiflavus.....-.....-..---2.---i2¢2-0-2 eee 125 Aphidus tesiaceipts: 2... >. 2022 55-% 22en- e 116, 125 Pachyneuron sp. a secondary parasite.......-..-.--.----------- 127 prey of Baccha dlevata ..\2:. 2... -2- 2. enh teen 132 wneicaginis, host of Aphidtus testaceipes. i... . 2. -..-. gk eee 116, 125 prey of Bacchd clavala..\- 2. 2. Sess pt ep des ee eee INDEX. 147 Page A Scie middletoni, host of Aphidius testaceipes....--..-..------.------2------- 116 Rm, Tass, Of A phelinis Mele: 6: Loe Tees Jes eeu . 123, 125 Seemrnerr, host, of A’phidius testaceipes'..22 aes: 425.1. ead. ee 116, 125 on peach, host of Aphidius testaceipes.............22022-022-2e eee ee eee 117 eee Bost of Apinidiys desiacerpes: bijeckin As Sees Qe AL. 116, 125 meer). Host of A phetinwswialies sot ashes: Secten! Jueves... 123, 125 Bee HOt, Gl Apneinus Mal >. . 2. soe s+. ames awd ew 122, 125 Wis S. dash ten ie ees Sen aires see 123, 125 AE DEREIS [OSUICEL POS: ok 2 = 2 RASS DOEES SONSERE I Lee 116, 125 Pachyneuron sp., a secondary parasite...........-------..--.--- 127 Beat Deceit elavanier wes. bs ioe ty cece 2 he TS 132 Pee 6 PIU TESIUCPI pS th0 24. ol ee eos dees Mees 2 125 viticola. (See Macrosiphum viticola.) Arrhenatherum clatius, food plant of spring grain-aphis in Europe.........---.-- 41, 43 Astragalinus tristis, enemy of spring grain-aphis...........--.--------------- 135 Audibertia stochoides, food plant of Macrosiphum sp..-..-...------------------- 117 Avena barbata, food plant of spring grain-aphis in Europe-.-.-.......--------- 41, 43 ENE et CH RETIEN, CLOLUUS®..2 © 25 6 ee a eet lee Ger ree dues suede 41, 43 fatua, food plant of spring grain-aphis in Europe............-.-------- 41, 43 sativa. (See Oats.) ammumevora, enemy of Apiis maids. -.- 22. 2...22. 25228). eet. ee eke 132 WEG sy oe ones Se dwt eee ee Ae 132 ETT CEA sash se Deh lp ga ER ig He Se PRES Te 132 emis gimnnels, iood plant of aphidid...........2+-..-.5-.222---2s0-..- 117,125 Barley, food plant of spring grain-aphis in America......................----- 43 Tiqiegpeds 520.8 Beck A oycta ee he eS “Bermuda grass,’’ food plant of spring grain-aphis in Africa................... 43 NE Mee APHIS GUC S22 25 J). 0s Se aac gaia sie Des Lael eels ooPe we 135 PgCrOsi ue GQUONnOMMM 02.4 wet Sela eeis bo Meliss food. wanes < 135 Spring etawni-a mips a i. He ae een Fs JaGdet hoc G .yusle eee. . 135 Black gum. (See Nyssa sylvatica.) Bluegrass (see also Poa pratensis). ee PG Ol FO PUlOSi PMU POP: since sn = vos welche lode. te.’ 2 - 123 African. (See Andropogon hirtus.) Bromus commutatus, food plant of spring grain-aphis in America.............- 42, 43 erectus, food plant of spring grain-aphis in Europe. ....-...........-- 41, 43 hordeaceus, food plant of spring grain-aphis in Europe................. 41, 43 inermis, food plant of spring grain-aphis in America................-.-- 42, 43 maermnus— Bromus villosus...222.. 2... oc sebn se ies deeds steed eaee.- 41, 43 EMS POMS MONUCILCUS: 5... «4 ae vit ceeaeet bee. . yale 2 41, 43 porteri, food plant of spring grain-aphis in America.................-- 42, 43 secalinus, food plant of spring grain-aphis in America..........-. «. 41,4248 tectorum (?), food plant of spring grain-aphis in America............. 42, 43 unioloides, food plant of spring grain-aphis in America.........-...-- 42, 43 villosus, food plant of spring grain-aphis in Europe.................- 41, 43 See Gray against spring prain-apliis.: 22 ..5e-02 4. v2ee 25-2 sen as fee J. eden 136-137 Buckwheat. (See Fagopyrum esculentum.) Burning-over infested spots against spring grain-aphis.................22-2..-. 137 pastures against spring grain-aphis-......-...-:..........--.--- 142 Capriola dactylon, food plant of spring grain-aphis in America................. 42,48 Buropees.? uses fol 43 Capsella bursa-pastoris, food plant of aphidid...........-......-----.-.--.-- 116,125 Cecidomyiidz, enemies of spring grain-aphis..........,..-..-2+-0222+-2+-00- 133-134 148 THE SPRING GRAIN-APHIS OR ‘‘ GREEN BUG.”’ Page Chxtochloa ttalica, food plant of spring grain-aphis in America................. 42,48 viridis, food plant of spring grain-aphis in America..............-- 42,43 Chaitophorus sp., host of Aphidiwus testacerpes. 22023 2822223 2. a 116 Megorismus sp. a secondary parasite......-.----2.-+.2-21<2- 126 Pachyneuron sp. a secondary parasite .......-----..------.- 128 viminalis, host of Aphelinus semiflavus......-..---5...---+---- 123, 125 Cheat. (See Bromus secalinus.) Chenopodium album, food plant of aphidid.. . 02.2222 ...-.----.--25-2eeee 116 Chess, soft. (See Bromus hordeaceus.) Chrysopa plorabunda, enemy of spring grain-aphis................-...------ 132-133 Coccinella abdominalis, enemy of spring grain-aphis.-.................-.----- 129 9-notata, enemy of spring grain-aphis..-.....-.--.-.....--..-22---22 129 Colopha eragrostidis, host of Aphelinus malas... 2222222. .0. 82 ee 123, 125 Corn, food plant of spring grain-aphis in America.........------------------- 41, 43 Burope: -.. 22... 02 Se 41, 43 Couch grass. (See Agropyron repens.) Cricket, snowy tree. (See Ecanthus niveus.) Crop rotation against spring grain-aphis..........)0...2.) 2.22222 141 Cultural methods against spring grain-aphis..............----------------- 139-142 Currant, food. plant of Myzus ribis...........22..---2-:-++=-+voe)- eee 125 Cynodon dactylon. (See Capriola dactylon.) Dactylis glomerata, food plant of spring grain-aphis in America.-.....-.----.- 41, 42, 43 Burope. -.-:.2:22eeeeee 41, 43 Distichlis spicata, food plant of spring grain-aphis in America............----- 42, 43 Drag. (See Brush drag.) Echinochloa crus-galli, food plant of spring grain-aphis in America............. 42, 43 Eleusine indica, food plant of spring grain-aphis in America.....-.-...-.---.--- 42, 43 Elymus canadensis, food plant of spring grain-aphis in America............- 41, 42,43 striatus, food plant of spring grain-aphis in America.........--.--.--- 42, 43 virginicus, food plant of spring grain-aphis in America.........---.-.- 42, 43 Eragrostis megastachya, food plant of spring grain-aphis in America.........-.- 42, 43 pilosa, food plant of spring grain-aphis in America.........-.....--- 42, 43 sp., Aphidius testacerpes swept therefrom........-.-.-.------------- 117 food plant of aphidid .. ..2.29-7.. SS Sto 2 11773 Eupeodes volucris, enemy of Aphis avene:...1..02..-..... 1... 2. 130 spring grain-aphbis. ......_...2). 7 > eee 130 Fagopyrum esculentum, food plant of spring grain-aphis in Europe..-..........-. 41, 43 Fescue, hard. (See Festuca duriuscula.) } meadow. (See Festuca elatior.) sheep’s. (See Festuca ovina.) various-leaved. (See Festuca heterophylla.) Festuca duriuscula, food plant of spring grain-aphis...............------------ 42, 43 elatior, food plant of spring grain-aphis in America.......-....-------- 42, 43 heterophylla, food plant of spring grain-aphis in America..........----- “ts ovina, food plant of spring grain-aphis in America............-------- 42, 43 rubra, food plant of spring grain-aphis in America........-...--...---- 43 Fungous disease of spring grain-aphis................-.---222e0--- errr 136 Grass, Bermuda. (See Capriola dactylon.) blue. (See Poa pratensis.) couch. (See Agropyron repens.) Italian rye. (See Lolium multiflorum.) Johnson. (See Sorghum halepense.) rye. (See Elymus canadensis.) INDEX. | 149 Page. Goldfinch. (See Astragalinus tristis.) Grain-aphis, spring (see also Toxoptera graminum). aberrant, dnGchyiaialss Val ee Se, ee 81 age at which females begin reproducing......-...--------- 70-71 Mt CHCMITED, cat Sue & a POL II eh nk 136 akbaek, iC haralehen rath Nis Wit o4 4aEh 8s OR os ee 44 nied emenesse CRON SNM I se 135 bith! Of young cc de enreneeecetee SP OA oo wc el SBR . 63 confusion with Macrosiphum granaria.......-----.--------- 13, 23 description of different instars): 92. 22909908. 2.22.2. ee 58-59 SUMMER AOMMSANIID go. ee ke be 59-61 diffusion, influence of temperature thereon.......-...-.-- 88-94 Wind SeMOPeON 2 2 2s25k 4.252524 65288 81 distribution in the eastern hemisphere-.........-.--.------- 16-18 Wester henligphere MORE. 24.2. 5552045 18-19 earliest observations in America.....-..-i.2/2:-.---------- 13-16 Canin records iar MatopelseUruue. . 25 Ll. eee nkk ees tS 16 Se mcsGi pilOMe ss .tVel Ue RA BE ORL ENB os ee 95-97 MIG OOD: iMate Shc ee Ca IMB: Sc at es 94-103 GUBEEVATIONS SL Nd) Jae? Mes es 2 97-102 MINI UL eek cee stk shaker eee 102-103 Seeniadaes soeee Serer aU EROS. rs fees SR Le ES 103-136 nuscellanenusit. 20 i..22. 22... Aa Cee eer a 135-136 fecundity ol OwaparOuntortins loi Pycee ec d 81 Wivaparous femalescs.ses202.0 224s kL ee 73-75 wingless versus winged females............-- 75-76 first generation, fifth instar or adult stem mother, descrip- ai omens olgor Jen cy Renee ip bps 58-59 finstiinstar, ‘deseription:<.-2...-2::-..4022- 58 fourth anstar, deserpiion: .2.24 20.6220. 58 second aetar, description... 22.2. 58 thirdhinstar, description. +.02.. 221.252... 58 LHL CL Sp AML I, ee AD PL OS NE oo ok 41-43 PU OMIS: CHMCTAY oes ice a iebe pee ae ee Ae re SRE 53 136 aenecrations; aumbersc. fier vr) oe 52-57 pieryedr x. 222 ef esheets a! 63-70 lnteratune.consultede sie. NSH YASS 220o 2 PE as 144 lenge niy ssh 2a te BU he Eee. Ser Peo a f2 ORSERES! MEP ialy BAlehs LO SL id 80 losses\irom depredationstim 1907. 2/25. 2226. eT 39-40 methods and material for embryological studies.......... 95 nueratary female! descriptionwe: by Josey. bind oe 60 HON Toot Vs TE RSS ANS oO a 61-62, 78 number of generations per year......222.-222-.22.2.004.. 63-70 URSA SAA AHO, CULT be Danek RO 61-62 ovipanousdéevelopmient: 0.25) .2 i. SNS... 78-81 jemale, deseriptions:ity. joka, PAO 77-78 Tormey feacumcdiiynts 4. ee ORAL. Art ee 81 oviposition, age begun by females....................... 78-79 RICCI SS Heer Uae. re SG Cd. eee 79-80 PUBCON PAETS Si oN Lines. Borel eit oe 79 emeeresOr 18906 ss aa ne cel SRR, ae. JU 19-24 150 THE SPRING GRAIN-APHIS oR ‘‘ GREEN BUG.’’ Page. Grain-aphis, spring, outbreak of 1903 .....-....4--4204 wetdcesss). 2 24-26 1907 cue pening ee wes. ah Le aoe) 2 27-38 parasites, primary or trues. joareie.. 4-43 104-125 secondary.» od weds coek Ae de. cee 125-128 predaceous enemies... . .-<.-=..-.. 258 s6en9-Liees 2a eee 128-136 preventive and remedial measures-..........-...------ 136-143 pupz, measurements of antennal joints..-...............- 61 rearing methods.....---.-.<<.-- 4609-0 eee 51-57 remedial and preventive measures......-.------------- 136-143 remedies, artificial introduction of parasites. ........! *.. 142-143 cultural metheday «i. ...-.---+=--2 eee 139-142 field experiments... 2s J 12: .«.2ucihds 2S eee 136-139 treatment of affected spots..........-----.--- 140, 141 reproduction, age when begun by females.................- 70-71 reproductive periodssss.-2--.-----------.:>-.20=e=eeeee 71-72 sexual forms. 2.2.2. is. aacilesdeel: etl sge ss ae 76-78 descriptions... | s.<):.+20 2Jeee. 2 a 77-78 situation in 1911... .....--...9d2o5eet: ee 40 stem mothers. .....-..-2---2-.--55220740208—2 ee 58 summer forms, first instar, description...................- 59 fourth instar, description ... .. ..-2225008ee8 59 second instar, description... ....-........ 59 third instar, description. . . . ..4-228e5eeae 59 viviparous development.:.222 . so... <-. 222 53-2 ee eee 44-78 in the North... °>.- -. 2233eeeeeee 49-50 © South......... 23223 44-49 female, fecundity ..2.. 202224: 2202-2 oe eee 73-75 winged male, description..:-.......---.-------525===eeee 78 viviparous female, measurements of antennal joints... 20) 02: sJ2cel...-.-2.-.-- 4. 26 61 wingless female, description... ..........----.3..38emeee 60, 61 versus winged females, fecundity. -............. 75-76 young produced daily, average number-........-...-....- eae Grazing, close, against spring grain-aphis..----_ -..20.:-4-.-250)_-2 eee 142 “Green bug.” (See Grain-aphis, spring.) Gum, black. (See Nyssa sylvatica.) Harrowing infested spots against spring grain-aphis............------.-------- 137 Hippodamia convergens, enemy of spring grain-aphis...........--------------- 129 - Holcus halpensis, food plant of spring grain-aphis in America ....--.-------.-- 43 Hordeum cespitosum, food plant of spring grain-aphis in America....--..---- 42, 43 jubatum, food plant of spring grain-aphis in America.........---..--- 42, 43 murinum, food plant of spring grain-aphis in America...........---- 42, 43 Hurope...2o.. 2 Seen 41, 43 nodosum, food plant of spring grain-aphis in America. .......-..---- 42,43 pusillum, food plant of spring grain-aphis in America............. 41, 42, 43 vulgare. (See Barley.) Hosackia glabra, food plant of Myzus spi..c.25.. 202620. -------2---.2 eee 117, 125 Hyalopterus dactylidis, Allotria sp. a secondary parasite. .......-.-.---------- 128 Megorismus sp. a secondary parasite... ......--------- 126 Juncus tenuis, food plant of spring grain-aphis in America..........---.--.---- 42,43 Kerosene emulsion against spring grain-aphis................-..------------- 138 Kochia scoparia, food plani of aphidid...........-080i 0. dseediem. -.. see 116 ap., $000. plant of aphidid... ....--.s+..«s.d08f.-<.<1.-..2s0ccee 125 INDEX. 151 , Page. Lacewing flies, enemies of spring grain-aphis....................2------ .. 132-133 Ladybeetle, convergent. (See Hippodamia convergens.) nine-spotted. (See Coccinella 9-notata.) spotted. (See Megilla maculata.) Badyhbeetles, enemies of spring grain-aphis...............0205-0..-.02------ 128-129 mame and sulphur against spring grain-aphis....2. 0.222. 02.2. 5.202222 202-2262 139 mepolems piceus, parasite of spring grain-aphis.:. 20.2.2... 2.220002 02 eden 136 Renin OL Apiidid...... 0c. cine li deeig. out pees 116, 125 Lolium multiflorum, food plant of spring grain-aphis in America............- f 43 perenne, food plant of spring grain-aphis in Europe...............-..- 41, 43 Lysiphlebus abutilaphidis= Aphidius testaceipes.........-.-.-.---2----------- 104 facrraraphidis—=A piidints testacevpes. 2. Su. 242924), ek Ea 104 hasilaris= Aphodius testaceipes.....0. 2... 222+. , Wines ORD eee 104 Ben mus pedis Lestaceipes=\awit,2...). 22eweg LAO 2s op as eZ 104 coquilletis (?)=Aphidius testaceipes........------ ROR 3 as Ss 104 ere) — Apindus Testacer pesos. ons 2oln Cae, Jee Jee. WS 104 pucunbitapudis—A phidius téstacéipess 2020. 6022 282229 SI 104 Hagrostaphidis—Apiidius testacei:pesiii04 3 2. 2s 2a PI 104 Best ——A piidius testacer pes]: . 228. a... nse le SUVS SLE Se). 104 NTS 9A Plidus CEStacei pes... 2s. --2a- oe eee. Hawes Syed. 104 6S TEStACeI Pes 4. dS OL Pes ee) oO SL 104 persiaphidis= A phidius testaceipes......------ acaba) NT Ns 104 pone pinais— A phidwus lestacerpess. 20.6632. 22 Pek beeen is-- 104 Pectin tS — A plidiius Lestaccipes 1444 eee Sah. e Peo eee 104 Meee A Dies LESIACCI OSs... 2) 60s ole SLI 37, 104 Macrosiphum cucurbitx, host of Aphidius testaceipes.............------------ 117, 125 erigeronensis, Pachyneuron sp. a secondary parasite TSR a 17 granaria, host of Aphidivus avenaphis..... 00022904. fo2e 2052 ek ee 125 estab pCO SIs &: IHL Jee) 22a. 116, 125 in North and-South? Carolima. im 1907.22.22. 2220200 2k 36 males and oviparous females in rearing cages in Texas. - 47 Pachyneuron sp. a secondary parasite........--..------ 127 prey of Allograpiaobligiiaisoto Ue Se sees alee hts 32 POETS: 2.35 Se RS SD oy, eae) eat salt 135 Sipherophoria aylindricas.e: sui ys a2 ee. 131-132 SUT phus CMenCHWUS Sees ys) ee IAS Lise 131 spring grain-aphis mistaken therefor.........--.-.------ 13, 28 pist, Megorismus sp. a secondary parasite...............-------- 126 jose. Hostal A phelinis males 1 2bGens UPL ee ae oe 123, 125 sp. on Abutilon, host of Aphidius testaceipes.........----------- 125 black gum (Nyssa sylvatica), host of Aphidius testaceipes. 116, 125 viticola, Allotria sp. a secondary parasite................------- 128 host.eb Apihidius testacerpesonti ars 228 0s P. ba Meh eA 116, 125 Pachyneuron sp. a secondary parasite.......-....-.-- 127,128 eemnre-aeains! spring erain-aphis. 2. ).02002..0 0.2 2.508 ek eee ee 138 Medicago sativa, food plant of spring grain-aphis in America.............------ 42,43 Megilla maculata, enemy of spring grain-aphis............-.---------------- 129 Ee aety Op», Monies Yas, SUTONEL A. oe FOOL. haa be SOP Eds ow ee dee ee 125-126 secondary parasite of spring grain-aphis. ...........-----.- 125-126 Melanoxantherium sp., host of Aphidius testaceipes..........---------------- 116, 125 Melospiza melodia, enemy of spring grain-aphis...................--..---+++-- 135 Millet. (See Chetochloa ttalica.) Japanese. (See Echinochloa crus-galli.) 152 THE SPRING GRAIN-APHIS OR ‘* GREEN BUG.’’ Myzus mahaleb, host of Aphelinus malt... 2 .422.22e5-¢2l es. ). oo Loe 125 persice, Allotria sp. a secondary parasite... ....--.... oi ee 128 host of Aphelinus semiflapus. ceste: AS ican 123, 125 Megorismus sp. a secondary parasite... .........-..is225----2 126 prey of Apludoleies sp. ....cvbisdcleseebee a 133-134 ribis, host of Aphiudius testaceipes.... 550i. ohese Shed ee ee 117, 125 . sp. on Hosackia glabra, host of Aphidius testaceipes...........-------- 117, 125 Nyssa sylvatica, food plant of Macrosiphum sp....-...-..------- ene 116 Oats, food plant of spring grain-aphis in America..................-..5-l25e2 41, 43 Burope:: 2.2233 1.unv.. 2 ee 41, 43 Cicanthus niveus, enemy of spring grain-aphis..........---...---------------- 136 Oryza sativa. (See Rice.) Pachyneuron sp. hosts...... - «= <= -s00s0045 aoeeR eee 127-128 probable parasite of Aphelinus sp2c.-.:..-+.4)..e.34e 127 secondary parasite of spring grain-aphis...........-..--..-- 127-128 Panicum sp. food plant of aphidid.........-2sc¢esc2 41 + Se ek ee 123 Parasites of spring grain-aphis, artificial introduction.............-..------- 142-143 Passerculus sandwichensis savanna, enemy of spring grain-aphis......-..-..-.- 135 Pasturing. (See Grazing.) Peach, food plant of aphidid..........<......s8este4 eae 125 Pempligus fraxinifolu, host of Aphelinus mali . ... 525.282. 2 da=2 See 123, 125 Pigweed. (See Chenopodium album.) 4 (?), food plant of aphidid ..... as 222224-.<32454. »- ae 125 Plowing-under infested spots against spring grain-aphis.......---....---:---. 137 Phini; food plant of aphidid . . . . . ...<-<...-+-e.poesest -oes oe eee 116, 125 Poa annua, food plant of spring grain-aphis in Europe.....----..------------ 41, 43 compressa, food plant.of spring grain-aphis in America...........------- 42, 43 pratensis (see also Bluegrass). food plant of spring grain-aphis in America......---.--------- 42,43 Polypogon montspeliensis, food plant of spring grain-aphis in America....-.-- 42,43 Poecetes gramineus, enemy of spring grain-aphis..........-.....------------ 135 Quail, enemy of spring graim-aphis . 0.22424 3. soe 25 - eee SE... 135 Rains, protracted, effects on diffusion of Aphidius testaceipes....-...---------- 121 Reduviolus ferus, enemy of spring grain-aphis..........-.-------------------- 136 © Rhopalosiphum pox, probable host of Aphelinus semiflavus......---.-------- 123 Rice, food plant of spring grain-aphis in America: ........-.-.----- 22a 42, 43 Europes.i 24). 4. 04242. ~.- - er 41, 43 Rolling against spring-aphis....% Js -cnedssuees ot ee coe oe 137 Rye, food plant of spring grain-aphis in America......-..---------+-++------ 41, 43 Schizoneura americana, host of Aphelinus mali............-----------+---- 122, 125 Pachyneuron sp. a secondary parasite. ......-.-.---..- 128 lanigera, host.of Aphelanus malice i. song ath de Ls 122, 123, 125 Scymnus sp., enemy of spring srain-aphiszn$o0 - P . ' +4 iyi wats + : ; ; BI and . 6 dh t ia chs Fee a Pe . i Mee len .: Sept ry A ee biPrapetpens teh: y Sirig aren ea ; ec : ici Hf wed _ | ; ii. 1?) sat Mae ty a eke Zz O e) < = < fa fe) OW a. Ab LL fe) ip) o 0} uJ | sh o Le NATURE OF DAMAGE. 91 It was noticed that in every case where the aphides were reduced by the effect of the heat, some small ones remained and upon ma- turing produced the following generation. In some cases not a single full-grown aphis was found after the hot weather had ceased, but many of the young aphides were present upon the vines. A similar observation was made at Santa Rosa, Cal. FOOD PLANTS. Phorodon humuli feeds principally upon the hop. It has, however, some alternate food plants on which the sexual forms develop. (See p. 14.) It is a common belief that the aphides found upon the shrubs and trees growing near the hopyards (see Pl. II, fig. 2) are hop aphides and that they later migrate to the hops. Specimens of aphides were taken from various plants growing near the hopyards at Agassiz, British Columbia, Independence, Oreg., and Santa Rosa, Cal., and identified. In no case was Phorodon humuli found among the aphides collected. Even though aphides may be extremely numerous upon such near-by plants, they do not in the least menace the hop crops; hence their destruction, from the standpoint of hop-aphis control, is unnecessary. NATURE OF DAMAGE. GENERAL EFFECT OF APHIDES UPON HOPS. The hop aphis injures the crops in two ways: By extracting the plant juices it prevents the normal growth of the plant, and by the excretion of honeydew, on which grows the black-smut fungus, Cladosporvum sp., it injures the quality of the crop. | In one hopyard at Santa Rosa, Cal., May 31, 1911, ceverel vines were found which were severely feria! Pater i in the season these vines were observed to have made little growth. The few hop cones which had formed were very small, some being only slightly larger than the burrs. Plate III, figure 1, shows some of these small cones compared with normal cones which were taken from near-by unin- fested vines. The relatively small growth of the infested vines com- pared to that of the uninfested vines is well illustrated in Plate III, figure 2. The vines in the foreground were severely injured by the aphides, while those farther back were only slightly infested until late in the season and made a very fair growth. Some vines that were only slightly infested were observed through- out the season. These vines grew well and bore a fine crop of hops, but just before the harvest the aphides entered the cones, extracted their vitality, and covered the scales with honeydew, in which the black-smut fungus soon established itself. These cones were so 99 THE HOP APHIS IN THE PACIFIC REGION. severely injured that they were not worth picking, and they were left in the field. (See PI. IV, figs. 1, 2.) Where control work is attempted the infestation seldom becomes so severe as to retard the growth of the vines, and it is the late injury— the accumulation of honeydew upon the cones and the resulting growth of the black fungus—which is most to be feared. HONEYDEW AND ITS EFFECT ON THE HOPS. Honeydew is a substance which is excreted from the anal opening of the aphides. It is composed largely of gums and sugar and is sticky and sweet to the taste. On warm afternoons it may be seen falling as a mist from severely infested vines. Hops covered with honeydew are sticky, do not have the normal -amount of crispness, and when pressed between the fingers remain flattened out. Honeydew may under some circumstances increase ~ the weight of the crop. One grower estimated that he made $1,000 on honeydew in 1911. However, the quality of the crop was greatly injured, and had the demand for hops been less the grower would not have been able to sell, and his crop would have been a complete loss. Even though under certain uncontrollable circumstances the pres- ence of honeydew may increase the income from a crop of hops, their quality is injured, and the honeydew is the medium for the black-smut fungus, which will, in ninety-nine cases out of one hundred, so injure the quality of the crop that it will be unsalable. BLACKENING OF HOPS. Neither the honeydew nor the aphides are directly responsible for — the blackening of the hops. The blackening is due to a smut fungus (Cladosporvum sp.) commonly called “mold,’’ which grows upon the honeydew. If the honeydew happens to be upon the hop cones, this fungus gives the hops a black, moldy appearance, which is sei undesirable. NATURAL ENEMIES. Several predaceous insects have been observed attacking the hop aphis at Perkins and at Santa Rosa, Cal. The ladybirds Hippodamia — convergens Guér., Coccinella californica Mannh., Coccinella abdominalis Say, and Chilocorus orbus Cas. were frequently found among the aphides. Some eggs of Hippodamia convergens deposited among the hop aphides are shown in Plate V, figure 1. Chrysopa californica Coq.. was always abundant in the hop fields, and the larve were very active in feeding upon the aphides. The larve of syrphus flies (Pl. V, fig. 2) were abundant in the hopyards. Syrphus opinator O. S. and Syrphus americanus Wied. were reared from the larve which were collected from hop leaves. , . Ss a CONTROL OF THE HOP APHIS. 23 A small predaceous bug, Triphleps insidiosus Say, was occasionally observed among the aphides. The following insects were observed by Mr. Theo. Pergande attack- ing the hop aphis at Richfield, N. Y., in 1887: Triphleps insidiosus Say Camptobrochis nebulosus Uhl. Adalia bipunctata L. Anthocoris sp. Stethorus punctum Lec. Parasites and predaceous insects destroy large numbers of hop aphides, but in no case have they been observed successfully to con- trol an infestation. CONTROL OF THE HOP APHIS. AXIOMS OF SUCCESSFUL CONTROL. In the economic control of the hop aphis, as of other insect pests, there are certain underlying principles which must be adhered to if the work is to be entirely successful. (1) All of the machinery to be used must be capable of doing effective work and. must be in good working condition prior to the time at which spraying should commence. (2) Spraying must commence at the proper time; it must not be put off. (3) The material used must be carefully prepared and thoroughly but not wastefully appled. | These are fundamental principles, and control work will be less effective and more costly if they are not closely adhered to. INSECTICIDES USED. Several contact insecticides have been used to control the hop aphis. The most extensively used sprays, however, are tobacco decoctions with whale-oil soap and quassia chips with whale-oil soap. In order to obtain exact data upon the effectiveness of these materials upon the hop aphis a series of experiments on a small scale was con- ducted at Santa Rosa, Cal., and notes were taken from experiments made on a large scale in Oregon. Tag counts were made; i. e., 20 tags were tied to as many leaves, and records of the number of aphides on the leaves before and three days after spraying were made on the tags; the percentage of aphides killed was thus accurately obtained. TIME TO BEGIN SPRAYING. It is very desirable to spray all plums or prunes that are infested by hop aphides as soon as the infestation is observed, both in the fall and in thespring. This will check the migration and lessen the infestation of the hops. The hops, however, should be sprayed as soon as the 24 ‘ THE HOP APHIS IN THE PACIFIC REGION. aphides become numerous. This is usually from June 1 to 15, though in some cases it may be earlier. It is well to spray first the fields which are most seriously infested. te It is usually desirable to wait until the vines are stripped before spraying. NUMBER OF APPLICATIONS. The number of applications which are necessary to control the aphides will vary with the seasonal and local conditions. The object is to prevent injury to the vines and to have the vines practically free of aphides at the time hop picking commences. To obtain good re- sults it is usually necessary to spray the vines from two to four times. NECESSITY FOR EARLY SPRAYING. Mr. H. N. Ord, who directed some very successful spraying opera- tions in a large hopyard in Oregon, claims that the secret of his success was early spraying. He began before the aphides became very numerous and continued as long as there were any aphides in the field. Yards sprayed under Mr. Ord’s direction were practically free from aphides, while the crops of a near-by grower were so severely damaged that 10 acres were left in the field unpicked. NECESSITY FOR THOROUGH WORK. The insecticides which are used for the hop aphis kill only by actual contact, and if satisfactory results are to be obtained it is absolutely necessary that the spray be thoroughly applied. Running the spray up and down the vine is not sufficient, because all of the leaves must be thoroughly wetted on both surfaces if good results are to be obtained. PROCRASTINATION. In sections where the aphides are frequently controlled by weather conditions some growers are likely to delay control work, hoping that a hot, dry wind will relieve them of the necessity of spraying. In one hop-growing section of California such a wind has appeared regularly for several years, but during the past two seasons (1911-12), which were favorable for the aphides, it did not arrive. Many growers, depending upon this wind, made no effort to control the aphides until late in the season, when much damage had been done. It was then difficult to make much progress against the insects, and severe injury resulted. SPRAYING EXPERIMENTS. The nicotine solutions appeared to be the most promising materials and were therefore the most extensively used in the experi- ments. The following tables, arranged according to relative costs, CONTROL OF THE HOP APHIS. 25 show the results of these experiments and give the cost of the mate- rials per 100 gallons of spray: TasLe V.—Results of spraying experiments for the hop aphis, with costs of materials per 100 gallons of spray. Experi- Number ; Cost per iment Materials used. Pressure. of ee < ae ene 100 gal- No. aphides. ee fed side. he eg -| Jons. Pounds. 1 ; Nicotine sulphate, 1 to 3,000. .... 80-100 1, 227 99.9 | June 15 | June 17 $0. 416 2 | Nicotine sulphate, 1 to 2,000... ..|.. 80-100 1,005 97-8 | dune 13") -dors-2- . 62 3 | Nicotine sulphate, 1 to 3,000; 80-100 3, 089 992 sume: V4 t=. -doesee- . 80 whale-oil soap, 4 to 100. 4 | Nicotine sulphate, 1 to 3,000; 80-100 1,990 95 Jato) WS [se Clon ase .83 cresol soap, 1 to 300. sh iam Cho) 2 ao ee ie ae nee ee 80-100 3,474 SA ould Oe: sale aed Once . 83 6 | Blackleaftobacco,1to75.......--. 80-100 1,810 94 RT Oscc ede GOreaas . 86 7 | Nicotine sulphate, £ to 2,000; 80-100 2,320 97 Pad Ose |e GOEseers 1.04 cresol soap, 1 to 300. 8 | Blackleaf tobacco, 1 to 60........ 80-100 2,590 OOF Sela Ores=- | adoneae. 1.08 9 | Nicotine sulphate, 1 to 1,000. .... 80-100 654 98:2) June 13) |2--doz--= 1 25 10 | Nicotine sulphate, 1 to 2,000; lye- 80-100 2,229 99.1 | Jume 15 |..-.do..... om resin soaps. 11 | Nicotine sulphate, 1 to 1,000; 80-100 2,512 99.4.| June 14 |_..do-.... 1. 42 whale-oil soap, 4 to 100. 12 | Nicotine sulphate, 1 to 1,000; 80-100 2, 780 99 Fone in| adores. 1. 67 cresol soap, 1 to 300. INEFFECTIVE MATERIALS. 13 | Limesulphate, 36° Baumé,1to86.| 80-100 1,950 14 June 16 | June 19 $0. 24 14 | Cresol soap, 1 to 300..-.......-..-- 80-100 129 0 June 13 | June 16 - 42 i} From the data in Table V it is evident that all the experiments except Nos. 5, 13, and 14 were quite satisfactory and that Nos. 1, 2, 3, and 4 were the cheapest materials to use. It was found that the nicotine sulphate without soap did not spread very readily and that the good results obtained were due to the very careful applica- tion. Either flour paste or soap should always be used with the nico- tine solutions. TaBLeE VI.—Spraying experiments conducted in Oregon against. the hop aphis during 1911. 10 EZ Number | - | Cost per Be Materials used. Pressure. of er Cent x a eet d 100. ea a aphides. 7 SEA Ces) © C- | gallons. ae | Pounds. 1 | Tobacco waste, 25 pounds to 100 100 213 100 | Aug. 22 | Aug. 25 $0. 18 | _ gallons water. 2 | Tobacco waste, 274 pounds to 100 100 253 100 |...do. Aug, 24 - 20 gallons water. 3 | Nicotine sulphate, 1 to 2,000. ........- 100 695 89 | Aug. 21 | Aug. 23 - 62 4 | Nicotine sulphate, 1 to 2,000; whale- Olmos), oO tot00. 22 so. eos. Ss - 100 529 U8) eG. a oreae tO. <2 . 845 5 | Nicotine sulphate, 1 to 1,000......... 100 73 100) |2 Ridors 22 22doeen2 1, 25 6 | Nicotine sulphate, 1 to 2,000; whale- | oil soap, 5 pounds to 100 gallons ite = ee esa eee tae ee 100 491 ORT een COE Sp iail OO! ae 1.475 7 | Nicotine sulphate, 1 to 750.......-.-. 100 130 97 | Aug. 22 | Aug. 25 1. 66 | 26 THE HOP APHIS IN THE PACIFIC REGION. Table VI represents the work done in Oregon by Mr. H. N. Ord and is in part a repetition of the results recorded in Table V. It also contains data upon tobacco waste, which appears very satisfac- tory and very cheap. If the decoction is allowed to boil or the tobacco happens to be low in nicotine, the spray will not be effective, and the vines will have to be ceed If this material be used each tankful should be tested upon some aphides and a record of efficiency kept. It is for these reasons not so satisfactory as a material containing a known quantity of insecticide. Nicotine-sulphate formulas for 100-gallon lots. Ounces Nicotine sulphate, -! to 1,000: .. - 222222 2S es sah oe 13 Nicotine sulphate, Ite 2,0002. 2 fe.2. a s2e22 = swt bs 25. - 5 64 Nicotine sulphate, 1 to 2,5000.. 5... 5.5.22 o- Sins oe. 9 a a= Nicotine sulphate; 1 to 3,000... 0.5.2.2 faJ ss. ten a Le ee 44 The formula ‘4-100,’ given for flour paste, means 4 gallons of flour paste (made according to directions) to each 100 gallons of spray. This paste contains 1 pound of flour in each gallon, so that there would be 4 pounds of flour (in the form of paste) 1 in each 100 gallons of spray. The formula “4—100,’’ when referring to whale-oil soap, means 4 pounds of whale-oil soap to 100 gallons of spray. Flour paste had proved to be a most efficient, cheap, and convenient spreader for the lme-sulphur solutions... Some experiments were conducted during 1912 with this material in combination with nico- - tine sulphate against the hop aphis. Table VII gives some of the | results obtained with this mixture. TaBLE VII.—Exzperiments in the control of the hop aphis by sprays of nicotine sulphate and flour paste. Number of Per cent eo! loins Formula. : ‘ 00 aphides | killed. present. gallons. Nicotine sulphate, 1-2;000;-flour paste;-4—100. .... -..-2-+--.-----2+--2:<-- 627 100 $0. 71 Nicotine sulphate, 1-2;500; flour paste, 4-100... ...........-..--.-----.----- 611 100 . 60 Nicotine sulphate, 1-3,000; flour paste, 4-100...........-.-..---------.+--- 1, 668 99 - 50 DO ee ate abies oo Bore ae eer ere ee ee eee ee 148 99 - 50 Nicotine sulphate, 1-3,;500; flour paste, 4-100... .. 22:2:.5.-...-5-26-22---- 208 100 - 45 Nicotine sulphate, 1- 4, 000; Hour paste, 4-100 220-2. 3-22: ees eae ee 271 96 - 40 From the results noted in the preceding tables it is evident that nicotine sulphate is effective in dilutions as high as 1-3,500, and that flour paste, 4-100, is an effective spreader for this material. The nicotine sulphate, 1—4,000, was not quite so effective, and it was also observed that its action was so slow that the sprayed aphides were able to deposit young on the leaves, thus reinfesting the hopvines. 1 See Bulletin No. 117 and Circular No 166 of this bureau. CONTROL OF THE HOP APHIS. aT - Nicotine sulphate, 1-3,000 and 1-3,500, in combination with whale-oil soap or flour paste has been successfully used in experi- ments, but it would be safer in practice to use the lower dilutions. In case the greater dilutions are used, careful observations should be maintained to be sure that the spray is doing effective work. The nicotine preparations which come in cans have a slight tendency to settle. In case they do settle and are not thoroughly mixed before measuring, the percentage of active insecticide used in one lot of spray may be enough less than should be present in a uniform portion to render the spray ineffective. It is advisable, therefore, to be sure that these preparations are thoroughly mixed before measuring. MIXING NICOTINE SOLUTIONS AND WHALE-OIL SOAP. During certain spraying experiments with tobacco extracts and whale-oil soap some difficulty was experienced in mixing the concen- trated solutions of blackleaf tobacco and whale-oil soap. When these were combined a greenish-gray precipitate of a flocculent nature _ was formed. A similar precipitate occurred when one of the mate- rials was diluted and the other left concentrated. When each solu- tion was diluted to half of the final amount, however, this objec- tionable nozzle-clogging precipitate did not appear. Flour paste does not have this effect, but when whale-oil soap is used as a spreader for tobacco sprays, both solutions must be well diluted before mixing. PREPARATION OF THE FLOUR PASTE. In preparing the flour paste, mix a cheap grade of wheat flour with cold water, making a thin batter without lumps, or wash the flour through a wire screen with a stream of cold water. Dilute until there is 1 pound of flour in each gallon of mixture. Cook until a paste is formed, stirring constantly to prevent caking or burning. (See Pl. VI, fig. 1.) Add sufficient water to make up for evaporation. If the paste is not sufficiently cooked, the resulting spray will not be effective. If overcooked, the paste will harden when thoroughly cool; it will then not mix with water very readily. Usually, how- ever, the paste is used as it is prepared, and overcooking is not a disadvantage. When mixed in a spray tank flour paste has a tendency to settle, and in order to do satisfactory work agitation is necessary. This is only a slight disadvantage, however, and is necessary with most spray materials. The large spray tanks are usually fitted with an agitator, and a hoe makes an effective agitator for the 50-gallon barrels, so that this problem is a.simple one. ~ 28 THE HOP APHIS IN THE PACIFIC REGION. ADVANTAGES OF FLOUR PASTE OVER WHALE-OIL SOAP AS A SPREADER FOR CONTACT INSECTICIDES. Flour paste costs 8.8 cents per 100 gallons of spray. Cheap flour © is always available, and the paste has no odor. Whale-oil soap costs 20 cents per 100 gallons of spray, is not always available, and has a disagreeable odor. 3 oe “4 Both materials have to be heated before using. ~< The neutrality of flour paste was proven by the fact that tide | applied upon the foliage and blossoms of the hop, in proportions as . high as 12 gallons of paste to 100 gallons of spray, no injurious ; effects resulted. When sprayed upon the hop burrs and delicate hop E cones, it did not prevent pollination or injure the appearance of the © { scales. QUASSIA. Quassia is the extract from the wood of Picrena excelsa, a tree occurring in Jamaica and containing the alkaloid quassin (C,,H,.O,,) in the form of crystalline rectangular plates. Quassia chips contain ne tannic acid. EFFECT OF QUASSIA ON APHIDES. A solution of quassia containing the extract from 5.33 ounces of quassia chips in 1 quart of water was diluted one-half and sprayed on Hyalopterus pruni on prune. It was found necessary to wash the waxy pulverulence from the insects before they could be wetted. The leaves were tagged with the numbers of aphides present and the twigs set into water in the laboratory. A check branch was sprayed -with pure water. That the strong quassia solutions have a decided insecticidal value is shown by the following data: Aphides present before spraying, 37, 40, 109, 92, 190, 75, 140, 40; total, 723. Aphides present after spraying. 0. 30, 3, 1, 0, 25, 0, 0; total, 59. Per cent killed, 92. Quassia solution at the rate of 7 pounds of chips to 250 gallons of water was applied to the aphides with the following results: Aphides present before spraying, 48, 60. 30, 40, 73, 30, 200, 100, 63, 128, 12; total, 784. Aphides present after spraying. 0. 0, 5, 0, 0, 0, 1, 2, 7, 9, 10; total, 34. Per cent killed, 96. The aphides on sprayed leaves turned brown when dead. The check leaves contained living insects only. Bul. 111, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VI. Fic. 1.—HINDU LABORER COOKING FLOUR PASTE. (ORIGINAL.) Fic. 2.—BoOILING AND MIXING PLANT USED AT INDEPENDENCE, OREG. (ORIGINAL.) FLOUR PASTE AGAINST THE HOP APHIS. CONTROL OF THE HOP APHIS. 29 THE USE OF QUASSIA, Various formulas for quassia spray are used i in the field and were observed to be effective when properly prepared. Some of them are as follows: Formula No. 1. Cents Paaseia chips, 7 pounds, at 5} cents per pound._.-_....2..--2--+-2-2---.+-2--- 37 Whale-oil soap, 9 pounds, at 44 cents per pound.......-...----.---.------ i 402 Water, 200 gallons. Total cost per 100 gallons. ....-.-.....-..--2.-2.-.-0-+- 31 Formula No. 2. Cents Quassia chips, 8 pounds, at 54 cents per pound........-.--- Chet ANN LS eater ee 42 Whale-oil soap, 6 pounds, at 44 cents per pound.........-..--..--.----.------ 27 ser tn) Pallons. 'Fotal cost. per 100 gallons. -..2...........-- 2.2 s.2+:- 69 Formula No. 3. Cents. Seat enips, 9 pounds, at. 5) cents per pound.-..-.-.-.--..-.-.3--2.-.+2%4- 47,2 Whale-oil soap, 6 pounds, at 44 cents per pound.....---...:---------------- 27 Water, 100 eallons- Fotal cost: per 100 gallons. ~2:4tt..- 2-222. ete e ee eet 74. 2 Formula No. 1 was used by Prof. W. T. Clarke in his work upon the hop aphis at Watsonville, Cal., in 1902. It was also successfully used by the writer in some field experiments at Santa Rosa, Cal., during 1911. The other formulas are stronger and have also been observed to be effective when properly prepared. PREPARATION. Many failures in control work, when quassia is used, are due to faulty preparation of the material. Some growers only soak the chips and use what soaks out. Others boil them without previous soak- ing. The proper way to prepare quassia spray, based on Formula No. 1, is as follows: Soak the chips 24 hours, then boil for 2 hours in 3 gallons of water. Add this decoction to 247 gallons of water in which the soap has been dissolved. The whale- oil soap is readily dissolved by boiling in a small amount of water. QUALITY OF QUASSIA. The quality of quassia may vary and the percentage of quassin which can be extracted from the different grades of chips will not be the same. For this reason the use of quassia chips is not se certain in its results as a material containing a known amount of insecticide. When the quassia chips are used, it is well to look over sprayed areas three days after they are sprayed to be sure that the spray has been effective. 30 THE HOP APHIS IN THE PACIFIC REGION. QUASSIA EFFECTIVE ONLY BY CONTACT. There is an erroneous impression among some growers that the quassia spray after it has dried upon the leaves will kill the aphides which later appear upon them. The quassia, as well as the other sprays used for the hop aphis, is effective only when im actual contact with the insects. EFFECT OF SPRAY MATERIALS UPON THE QUALITY OF SPRAYED HOPS. It was suggested by some growers that nicotine sulphate, whaie- oil soap, and quassia extract might injure the quality of the hops on which they were applied. In order to test this pomt some nearly ripe hops were sprayed with the following materials, and when the crop was being picked these sprayed hops were picked, dried in the kiln with the other hops, and later sent to Washington for analysis: Nicotine sulphate, 1-1,000; whale-coil soap, 4 pounds to 100 gallons. Nicotine sulphate, 1-2,000; whale-oil soap, 8 pounds to 150 gallons. Nicotine sulphate, 1-3,000; whale-cil soap, 4 pounds to 100 gallons. Blackleaf tobacco extract, 1-60 and 1-75, each with 2 pounds of whale-oil soap to 100 gallons. Quassia chips, 73 pounds; whale-oil soap, 9 pounds to 250 gallons. The following analyses were received from the Bureau of Chemistry: Taste VIII.—Analyses of hops sprayed with various insecticides. = Whalevoil = Ee No | soap. Nicotine ee Fe None. | None. y SE ea None. None. eee ee None. None. Pe ee None. None. eR oo | None. ) None. ie None None. The quassia was not tested for, as there is no test that is applicable. From the above analyses it is evident that the nicotine or whale-oil soap that remained upon the hop cones was not present in sufficient quantities to be detected by a chemical analysis, and therefore would not injure the quality of the hops. The flour paste is composed of starch and gluten, which has no distinct flavor or odor, and even through it were present in large amounts it can not be conceived how this material could influence the quality of the hops. DIRECTION IN WHICH TO WORK. Since the winged aphides travel largely with the wind, the best results will be obtained, especially where the winds are prevailingly from one direction, by working with the wind. [If this is done the CONTROL OF THE HOP APHIS. 31 winged aphides will not be able to migrate to the sprayed hops so readily as if the wind were blowing from the unsprayed hopvines to those which have been sprayed. CONTROL ON PRUNE. The hop aphis apparently is capable of migrating some distance, provided the wind is right, and in prune-growing sections it is impos- sible to kill all of the migratory insects. Where there are only a few prune or plum trees in the neighborhood, however, the destruc- tion of any nonproductive trees and any wild plums that may be present will reduce the number of trees that will have to be sprayed. The spraying of the plums and prunes can not be relied upon for the control of the hop aphis, but where it is thoroughly and systemat- ically done the severity of the season’s infestation may be greatly lessened. Work along this line is strongly recommended. FIELD OBSERVATIONS. About the time that the aphides are expected to appear upon the plum or hop it is advisable to go through the prune orchards or hop- yards and note the conditions. Careful observations, if maintained throughout the season, will keep the grower informed as to the severity of the infestation in all parts of his hopyards. He will then be able to check the infestation before-any serious damage has been done. SPRAYING REPORT. The following form of a daily report was successfully used by Mr. H. N. Ord at Independence, Oreg., in 1912, to keep a record of the spraying operations in the field: Effective- Formula ness of No. No. acres Cost of peo aetes eee ag cer Sa a cost spray ap- |machines| sprayed per; operations gallons. plied three! used. machine. per acre. - days before. Se eee ee ee ee ee ee If such a report is faithfully kept the grower will always know the condition of his hopyard and what his spraying operations are costing him. SPRAYING MACHINERY. Several forms of outfits may be successfully employed in the hop- yards provided that they meet the following requirements: The machine should have a tank capacity of from 75 to 200 gallons, 32 ' THE HOP APHIS IN THE PACIFIC REGION. - should supply at least two lines of hose at 120 to 150 pounds pressure, and should be in such order that there will be few breakdowns or delays. - Good work can be done with the hand pumps (see Pl. VII, fig. 1), the gasoline power outfits (Pl. VIII, figs. 1, 2), the compressed- air sprayers, etc., provided they meet these requirements and are supplemented by an efficient mixing and supply system. : The knapsack spraying machine (Pl. VII, fig. 2) may, under some circumstances, be of value for work on a very small scale, but is not — at all practical in a commercial hopyard. BOILING AND MIXING PLANT. In designing a boiling and mixing plant for work on a large scale it is very desirable to arrange the tanks so that-their fillmg and empty- ing is accomplished by gravity. The uppermost tanks should be used for steeping the materials and should be supplied with water from a hydrant; the lower ones should be filled by drawing from the upper ones, or, when diluting is necessary, from a hydrant. The lower tanks, however, should be high enough to drain into a supply wagon. DESCRIPTION OF TANKS. The boiling and mixing tanks at Independence, Oreg., were made of No. 18 galvanized iron, riveted and soldered together, a 32-inch iron pipe forming a brace for the tops. Three braces of 4-inch angle iron, placed 3 feet 4 inches apart and riveted to the sides of the tanks, together with a framework of 2 by 4 planks, prevented the tanks from bulging. ARRANGEMENT OF TANKS. The arrangement of tanks shown in Plate VI, figure 2, was found very satisfactory. Two boiling tanks 10 by 3 by 3 feet 9 inches, heated by steam, were placed upon a 10 by 12 platform, elevated 10. feet from the ground. Passageways were left between and around the tanks. On a near-by but lower platform were three 375-gallon tanks for mixing and storage. A swinging outlet pipe drained the boiling tanks and directed the materials into any one of the three tanks. From the Jower tanks the material was run through a long hose into the supply wagons. In order thoroughly to straim the materials the entrances of all the outlet pipes were screened with wire gauze and the ends of the hose were covered with cheesecloth. FIELD OPERATIONS. SUPPLY WAGONS. When extensive spraying operations are being carried on it is essential to have an adequate supply system. In an emergency a farm wagon containing barrels of spray (Pl. VIII, fig. 2) can be used, Bul. 111, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VII. Fic. 1.—HAND PUMP AND BARREL ON SLEDGE. (ORIGINAL.) FIG. 2.—KNAPSACK SPRAYING MACHINE IN USE IN HOPYARD. (ORIGINAL.) | SPRAYING AGAINST THE HOP APHIS. 4 na] MARde ss, ef 4 =: Se Sa eee et ete Bui. 111, Bureau of Eniomology, U. S. Dept. of Agriculture. PLATE IX. Fic. 1.—COMPRESSED-AIR SPRAYING MACHINE, SHOWING AIR BOTTLE, TANK, REDUCING VALVE, AND PRESSURE GAUGE. (ORIGINAL.) Fic. 2.—FiILLING AiR BOTTLES FOR COMPRESSED-AIR SPRAYING MACHINE. (ORIGINAL.) SPRAYING AGAINST THE HOP APHIS. CONTROL OF THE HOP APHIS. 88 but it is very desirable to have a large tank wagon made expressly for this purpose. When low spray tanks are used the spray can be run from the supply tank by gravity, but in most cases it 1s necessary to employ a good pump. EXCHANGE TANKS. When conducting spraying operations it is desirable to keep the entire force constantly employed. The use of an exchange tank is one of the best methods for accomplishing this purpose. An extra machine is filled after the other machines have started and is exchanged for the first one emptied. The exchange tank is driven down the row in which the nearly empty tank is working. When empty the men move back and take the exchange tank, the empty tank being then refilled and exchanged for the next empty tank. SPRAY RODS. When the hops are growing upon short poles the spray is most readily applied with a short spray rod. In the trellised yards, how- ever, the hops are much taller and a 10-foot rod is necessary. The aphides are mostly upon the underside of the leaves, and in order to wash them thoroughly the spray must be directed from below. When angle nozzles are not available the spray rod may be bent so that the spray is readily directed to the underside of the leaves. If one or the other of these methods is not employed the material will not be satisfactorily applied. } NOZZLES. _ By exercising great care it was found possible to spray the hop- vines thoroughly with a nozzle that produced a very fine mist spray. It was found much easier, however, to do the same work with a nozzle that produced a slightly coarser washing or driving spray. This type of spray is more satisfactory because by its driving force it turns the foliage and dashes over it. When cheap labor is employed good work is more readily obtained with the coarse driving spray than with the very fine mist spray. THE COMPRESSED-AIR SPRAYING MACHINE. The compressed-air spraying machine (Pl. IX, fig. 1), which is described below, was invented by Mr. Theodor Eder, of Perkins, Cal., who by the following statement has generously dedicated it to the use of the public. Whereas, I, THEopDoR Eber, of the town of Perkins, county of Sacramento, and State of California, having invented certain improvements in spraying devices for 1A copy of this patent (No. 1046572) may be obtained for 5 cents by addressing the Commissioner of Patents, Washington, D.C. 34 THE HOP APHIS IN THE PaCIFIC REGION. which I filed on the 20th day of March, 1909, an application for patent of the United = States, serial No_484784; and | Whereas. it is my desire that the public generally shall have the right to me said Invention, Now, therefore, I, the said Theodor Eder, hereby dedicate, srant and convey to the public ai larze and to whomsvever may desire to use said Invention, the full meht, Hberty and Heense to make, use and sell apparatus embodyme the said invention for the full end of the term of any letters patent which may be eranted on said applicaiion. And I hereby authorize and requesi the Commissioner of Paients io issue any lefiers patent which may be granted on said application to the people of the United Stafes and Territories thereof as the assienee of my entire meht, iiile, and imteresis m and to the same. In witness whereof, I have hereunto set my hand and seal] this 31st day of October, A. D_ 1912. Tazo. Eprr. This spraying machine (PI. IX, fig. 1) is composed of a large iron tank, fitted with a pressure gauge (/), an mlet pipe with a strong screw cap (2) which is opened with a large wrench (3), an outlet pipe with cut-off (4) and connected through a pressure-reducing valve ©) with a large air bottle (6). (A large carbonic-acid gas botile serves this purpose, the larger the better.) This machine is fastened onto a truck made from two old mower wheels and an iron shoe. Provided that the spray material is thoroughly screened so that no dirt gets in to clog the nozzles, this machine is effective and is so small nad light that it is readily hauled through a hopyard by one horse. The air bottles are filled with air compressed by the air compress- to 1,000 or 1,200 pounds (PL IX, fig. 2), loaded onto the supply wagon, and hauled with the spray to the field. The spray tank 1s filled, an air bottle connected with the reducing valve which has been set for 120 or more pounds pressure, the air is turned on, the pressure gauge — indicates the pressure that is maintained, and the machine is ready for work. The following information was received from Mr. Eder and gives data from which the cost of such a machine may be estimated: Replying to your request im this regard, we beg to advise that the cost of these mes depends upon the size of the spray tank, etc. A 150-gallon tank m black on would tank cost $10, including pressure gauges and fittings. Mowing machine wheels we buy old, costing from $1 to $1.50 per pair. The axles and other iron work on the truck cost in the neighborhood of $8, and the woodwork, efc., would probably bring the entire truck construction up to $15- The only things you would now have to add are spray hose, pipe, and nozzles, which expense would, of course, vary according to the — number of leads and the leneth of same. We usually use four leads, two of 16 feet and © two of 25 feet. We use seven-ply }inch hose, costing about 12 cents per foot, and use 10 feet of L-imch pipe for spray rod to each lead, and a hop nozzle, which costs xi mately 90 cents. The value of the pipe and valve would probably be $1. The ar bottles, if purchased im lots, cost $12; singly, probably $15. For farther information we eg to ad'viee that a crew of four spray kancia will ammiy 2 250-gallon spray tank on hops about five to six times a day, and this would require CONTROL OF THE HOP APHIS. 35 one full air bottle to each tank of spray. However, the same bottles are charged several times in a day, and on some ranches we run 10 or 12 spray rigs with three dozen bottles, and could probably get along with a few bottles less, if necessary. The air compressor we use is a 10 by 12 double-acting mine compressor with the valves removed from one end. The piston rod is continued on through and the initial compressor puts the air through pipes immersed in water that cool same, and the ram at the other end of the piston rod puts this air up to 1,000 pounds. We use XX }-inch steel pipe for leads, and usually fill three or four bottles at a time, or new bottles can be put on and others taken off, without stopping the compressor. The compressor we have designed will charge about 25 bottles per hour, if necessary, all from 1 000 to 1,200 pounds. Lately we are charging quite a lot at 1,200 pounds, especially where we use 250-gallon tanks. Cost of compressor, as fitted, $550. For small growers it would seem to us that they could club together and buy a com- pressor and bring their empty air bottles in for recharging, as a bottle gets away with a lot of spray even at high pressure. The reducing valves are so constructed that any pressure desired is obtained. We have also tried the use of carbonic-acid gas for spray- ing, but we use the spray material up so fast that the gas freezes itself up in the valve while coming out of the bottle when the pressure is being reduced. This could be overcome by the use of an alcohol lamp in the lead line, but this is too cumbersome; besides, air costs less. E. CLteEMENS Horst Co., By Tueo. EpER. COST OF SPRAYING. The following estimate of the cost of spraying for the hop aphis is made from data taken from actual field work on high-trellis yards. The amount of material needed for hops on short poles will be some- what less. It has been found that one machine will spray from 2 to 3 acres per day, and that in order to do thorough work it is necessary to apply from 300 to 500 gallons per acre according to the amount of fohage on the vines. The following data are based upon a machine which will spray 2 acres per day: Materials: Nicotine sulphate, 1-2,000; flour paste, 4-100. Cost, 70.8 cents per 100 gallons. 300 galls. 500 galls. Ppa per acres. .2.-).-.-..---- a SRE ays ee ee ey es $2.13 $3.54 mame sme, o2 per day tory day........ 22.2. ge eee ese 3. 00 3. 00 meee cents per day for4 day. 2... ss<... 22. J. 45-5 oe: eRe . 25 . 25 a otal cost per acre of 1 application...:..........2.-- ee ne 5. 38 6.79 QUASSIA AND WHALE-Om Soap.—Formuta No. 2. Beare tem ats per 100 pallong. 226s os ae Dla eck elk sete dele eek $0. 69 rE Manin ree ene ee re et Lr ee ke fe Sin ED YEal as dune 2 ol ti, en ea ie te et SN ae . 80 300 galls. 500 galls. EMSC ACTOR, yo ee ee Me Pee ok Tasha ee ole ses $2. 40 $4. 00 eemar ra ten), b2 pemday 10r 4 day a. .o-4...s-. 0. S2a THE MORE IMPORTANT WRITINGS ON THE HOP APHIS. CusrKe. W. T.—Bul. 160, Univ. Cal. Agr. Exp. Sta., 13 pp., 7 figs. . — Corpiey, A. B—Bul. 4, Oreg. Agr. Exp. Sta., pp. 99, 127, 13 figs., June. Habiis and remedies. Freur, E. P.—Proc. 24th Ann. Meet. Soc. Prom. Agr. Sci, pp. 39-48. 4 Frrcn, A—The Country Gentleman, vol. 25, p. 274, April 27. Desiructivemess, enemies, and remedies. Fretcuer, J— Bul. 46, Div. Ent., U. S. Dept. Agr.. pp. 82-88, May. Friercuer. J—Repit. Exp. Farms Canada, pp. 163-215. Howarp, L. O.—Country Gentleman, vol. 52, p. 875, November 17. First published full life history. Howagrp, L. O.—Bul. 7, n. s., Div. Ent., U. S. Dept. Agr., pp. 84-87. Howakgp, L. O. = Industry, Orange Judd Co., New York, pp- 113-141, 19 res. Accounis of the species known to aifeci hops. Korsete, A—Insect Life, vol. 6, pp. 12-17, November- Experimenis with hop louse im Oregon and Washingion. Laytner, J. A——Cultivator and Country Gentleman, vol. 52, p. 511, June 30. Remedies. Liytner, J. A—New England Homestead, p. 253, July 27. Remedies for hop 2phis. Liyrner, J. A—New England Homestead, p. 193, May 2. How io conirol the hop aphis. Luecer, O.—Bul. 69, Minn. Aer. Exp. Sta., pp. 250, 200 figs... 16 pls. Permit, R. H —Spec. Bul. 24, Mich. Agr. Exp. Sta.. pp. 79, 70 figs. Reiscu, Fr.—Zeitschriit fiir wissenshaftliche Insektenbiologie, vol. 4, no. 10, ; Pp- 363-366. | Important enemy of hops. Rewuscu, Fr.—Zeitschriit fiir wissenshaftliche Insektenbiologie, vol. 6, no. 6, p- 242. Mentioned in article on Adslis bipuncia‘a 25 the principal food of that species. Remiscx, Fr.—Zeitschrift fir wissenschaitliche Insektenbiologie, vol. 7, nos. 7 7-8, pp- 240-243; no. 9, pp. 282-285. Ariicle, “The hop leaf louse, A phis kemuili_.” Rutey, C. V._—Cir. 2, 2d ser., Div. Ent., U. S. Dept. Agr., pp. 7, 5 figs, I pL, Tas une. Ritey, C. V.—Insect Life, vol. 3, pp. 181-210, January. Riuzey, C: ¥.—Ann. Rept. U. S. Dept. Agr., pp. 199-226. 3 pls. Riey, C. V., and Howarp, L. O.—Insect Life, vol. 3, p. 350, April L¢ Ritey, C. V., and Howarp, L. O.—Insect Life, vol. 3, p. 486, August. 7 Hop lice on Pacific Coast. Riey, C. V., and Howarp, L. O.—Insect Life, vol. 4, p. $4. October. Quassia for the hop aphis. Ruiey, C. V., and Howarp, L. O.—Insect Life, vol. 4, pp. 342-343, June Hop louse in the extreme northwest. Ritey, C. V., and Howarp, L. O.—Inzect Life, vol. 4, p. 401, Ae Hop aphis remedies. Rizr, C. V., and Howarp, L. O.—Insect Life. vol. 4, p. 406, August. The hop louse in Orezon. Riey, C. V., and Howarp, L. O.—Insect Life, vol. 5, p. 60, September. The hop plantlouse in Washingion. Ritzy, C. V., and Howarp, L. O.—Insect Life, vol. 6, p. 53, November. Hop lice in New York State. MORE IMPORTANT WRITINGS ON HOP APHIS. 39 Sanperson, E. D.—Insect Pests of Farm, Garden, and Orchard, pp. 275-278, figs. 202-204. On hop. WasHBurn, F. L.—Bul. 10, Oreg. Agr. Exp. Sta., pp. 23-24, figs. 5. Description and treatment. WasuBurn, F. L.—Bul. 25, Oreg. Agr. Exp. Sta., pp. 9-12. Treatment. WasusBurn, F. L.—Bul. 31, Oreg. Agr. Exp. Sta., pp. 79-88, 3 figs., 2 pls., April. WasuBurn, F. L.—Bul. 31, Oreg. Agr. Exp. Sta., p. 82, April. ' Brief notes, with suggestions as to remedies. EN Di, xX? Page Per mpuncaa, enemy of hop aphis.. 0... 2.2)... 26.2.0... 05 5529. ms 23 orp. Chom y Ol bop-aphis.2... 2.52.05 ede ee ea 23 Pn mennO Oy ali. 3. 80. Lets wade Ae e Pee Re 3 19 Aphides on shrubs and trees near hopyards mistaken for hop aphis.......-.-.. 21 Aphis, hop, bibliography of more important writings. .............-- Ea 8 38-39 ; PEER elem yee 82'S eM od ERS ee hae Ce ee Da PULSES LOC et aaah ie GA CO Re a ieee, WOE, Renee Ee wi eg Meee Ce eae GS 23-31 Cable [i EE pegs hata oi SE ACI aN Bc oe NEO fe eet ol FEcOmMMINendatoOns, SuINTArY. : 2.0.0. 26/2 83 et 37 Srieethteee MAb tneies 6 yor sts edb eee SL AG Saas tee Ee 21-22, Peano Vane eyo! aa od Soe Soe LG oP ee 14-15 rN ONE wads em el Mes ct Oar lee es Ss oes Sea PR 9 Commie MMINOhANCe cai too aan eile ee ee eo Go parole ee _ 9-10 Seeeeeenicral Wpolmnopes oo. se ons ele PP ec See. Se 21-22 Paste MPM EDOM et enh eS os Sees oon SM ee ace 20-21 cere REE eet etn eae tn Lee a EC ie See os 17-18 Pmcroence ron) Wiberlabion.. 22 6.2. 202262. s. ek etc be eel. 12 Peete meee ge ho enh geal tae a ee ee sa 22-23 favorable and unfavorable conditions therefor. ............--.---- 20-21 field observations, importance in control work................--. 31 Operanions am, cOntrol Ve 2. 22. 2s Stason Sk a eee: 32-35 LAM PeALAICe- TM SCAsOMe:.cdj- 2 u's eee So Pe Eile le A Ses 20 MEE ANS er tne ee SL ie cli ea AT ed a ee 21 Beemeriions mumber on hoste) 2s.) 224) 4A see oe 13 Pome Ra ere Yee ES ue ee ee tee tk a es 15-16 LLP Une SE LSS ee i ce Sc eee aA pn Mee | Ae Ca CE Rien 19 WS DEES es BR ae RS gee i es Sain Ne eg er Len Btw Le etgetat: 19-20 head compared with that of melon aphis............---..--.---- 15 eM READIN -e Sore eA nD suet Oe hE ewido ek ead. LS De 10 emersence thereiroms, So2022 221 Joe. 2 Sons babs doch eae 12 PePPeiiCides UsEO Il CONTROL .2ce es bole Soe te Se a 23 BEN OMAN SS Oe ar Set nan ho ja a che ha Mes Ae da A Mena SU, 10-19 iets eta WUC be WOE Kero iih orice Mowe c oo ose | tare clad ge a ie 2 oe 10 Rares lets eee Nh aes Soe Be ee Na SE Te oe ik ca Ly Hmimer, theory repardine them... 20.0022 4.) ela. 18-19 MENU AOAC LIVELIER ond 2 5.5.) os NG Aa ee See bie ele he dua ear 13-14 RROD a a Ca ne nee A tsls oe de Ls ie Ge 13 necessity for thorough work in control... 2. ...22..-2-124.2.4242. 24 number of spray applications used in control. .............-..--- 24 young deposited by viviparous females..........-..-.-- 16-17 OE DRE UES ers 55a cee eta: tee ag Yea he Wer Ye Wh es aw 10-12 procrastination in control work, results... .-.- Ein Dat Sel ge Seer ag Ek 24 UCSC oe ieiguemnes 10 0 ty Dol Cag Ie NG a ee a a 19 POM AOU amlhs CRCECHOs2 2 2) Se Leos Je. Sot wtb es ao cde eke daw 19 42 THE HOP APHIS IN THE PACIFIC REGION. ; Page. Aphis, hop, reproduction, method _:.3 <- ==>. Ss. es . ‘ * ; , in a ; ’ ; U.S. DEPARTMENT OF AGRICULTURE, ier BUREAU OF ENTOMOLOGY—BULLETIN No. 112, eat oe LO, HOWARD, Entomologist and Chief of Bureau. : PRELIMINARY REPORT'ON THE =. ALFALFA WEEVIL 9° Pe f a a ae Ind Ls Peet eS Pee : S nae a - FM. WEBSTER, r£4 In Charge of Cereal and Forage Insect Investigations. + ‘ ie 3 : - a .S Be ee a a 7 ANSON instity, oe 7 hy < ae WASHINGTON: Wire GOVERNMENT PRINTING OFFICE. eee ip os 1912. eo 5a" Fre: < Ay Vond ; val es, DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 112. Ee. O. HOWARD, Entomologist and Chief cf Bureau. PRELIMINARY REPORT ON THE ALFALFA WEEVIL. BY F. M. WEBSTER, In Charge of Cereal and Forage Insect Investigations. Issuep May 14, 1912. iN) va : Zi Pel Ae x | AU 4 eo 1D inn YT ey NA Mah tS Be 5s \ Ks E i WASHINGTON: GOVERNMENT PRINTING OFFICE. 1912, OG a aeeOOOOEOEOEeerrrerrees re a BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Martart, Entomologist and Acting Chief in Absence of Chief. R. 8. Curron, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. CurrrenveEn, in charge of truck crop and stored product insect investigations. A. D. Hopxrys, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. F. M. Wesster, in charge of cereal and forage insect investigations. A. L. QuAINTANCE, tm charge of deciduous fruit insect investigations. E. F. Pururres, in charge of bee culture. D. M. RoceErs, in charge of preventing spread of moths, field work. Roiia P. Currre, in charge of editorial work. MaBet Cotcorp, in charge of library. CEREAL AND ForAGE INSECT INVESTIGATIONS. F. M. WeEBstTeErR, in charge. Geo. I. Reeves, W. J. Pumures, C. N. Arnsuige, E. O. G. Ketty, T. D. URBAHNs, Harry S. Sirs, Geo. G. Arnsiiz, J. A. Hystop, W. R. Watton, J. T. Monet, J. J. Davis, T. H. Parks, R. A. Vickery, V. L. Wr.pERMuts, E. G. Smy7tu, HersBert T. Ossporn, Pure Luernsiy, C. W. Creet, E. J. Voster, R. N. Wu- son, VERNON Kino, entomological assistants. Nettie 8. Kioprer, ELLEN DASHIELL, preparators. Mrr1am WELLES REEVES, collaborator. 2 LETTER OF TRANSMITTAL. U.S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY, Washington, D. C., January 2, 1912. Srr: I have the honor to transmit herewith, for publication as Bulletin No. 112 of this bureau, the manuscript of a preliminary report on the investigation of the alfalfa weevil in Utah and adjacent States. The investigations of the Bureau of Entomology in coopera- tion with the Utah Agricultural Experiment Station began April 1, 1910, and still continue. The period covered by this report is from April 1, 1910, to November 15, 1911. From April 1, 1910, to April 1, 1911, the bureau was represented in the investigations with but one assistant. Since that time the force has been increased until eight or nine persons have been from time to time employed. The information given is exactly what the title of the bulletin implies, preliminary in nature and not to be taken as conclusive in all cases. It is simply a short account of what has been done within the period of time just ‘indicated. Respectfully, L. O. Howarp, . Entomologist and Chief of Bureau. Hon. Jamres WILSON, Secretary of Agriculture. ———— CONTE NAS. Page I IRIE Oe es NS oo ene Se Eee deemed aoe eee Seat : 9 First appearance of the alfalfa weevil in the United States.................. 9 IERIE elt ere rie ree Ae Sia Ld ee oe EOE es bend Qh Se 10 feveseeamons by the Utah Experiment Station...-......:..----:..--+-+-+-- it Cooperation of the Bureau of Entomology and the Utah Experiment Station. - i Cooperation with other bureaus of the United States Department of Agriculture. 14 Variety experiment........ em eer chest Stal pols a) SVU Ln Sete ea 14 Maeade aioe ol vertebrate enemies. .............-.5......24-2-0+---5--- 15 Semimeerrmm correctly determined.................--..--.-+----2--+2-ee0- 15 imupestamee ol a second species in Utah.........:...-. 22-0222. -22e- een ee-ee- 15 Description and seasonal history of the alfalfa weevil. ......-...---..-------- 15 Reem I eM Oh oo nw ene s Leda. he ais disiege ree Ss 19 Bpience ota partial second generation.......---.-------+---+-+--------- 20 a ae Oe te es ite et ace Lae ee rae oe 21 Lbs, DMIELOC: So Roe a eee cae eRe ee eRe 22 eMmmnInermE MA PITAL so POR cs cies eee ete od oe oe eee ee 23 ENN I ee a oe cides wee ee ee e's eet ke ee 24 DemerrmenOMOMGIESION. <2 J. 5 cc ee oon ee - nee ee eee ee eee 25 Wield experiments in destroying the alfalfa weevil. ...............---------- 26 Rene Mice Mem OMPCTIMENtS... 2... oe. ee be ee we ee eet - at Sere me ENIMGM GS. 26.2 252 2. . se nps eee ee oe ee ee ee eee 27 Ses on im connection with irrigation. ........2.-..:..-----.----.---- 29 SENT EEECMT ee ate wt Se ee a gu ed 29 Reduction in quality of hay caused by the alfalfa weevil. ...............-.-- 30 EEE SS vo RS Se eR Sa ee 30 I le ee ees ee oe ae a bee LoS eee 31 Peegaeeous enemies... ..........-...- SE le ee SOE ae ned seeker a ot Serene mie WE Pans (Cree ee ee ea ee cade cn alate a cele Ha eleie 34 MMSE OMIIARAG THES crcects.) 202 22% 5 ie PEL oe we Bek aoe bane nein vale 34 EE TU GUTS Scale ey UE OO an eee ae Cae cae ee eS 35 Unley aig RENO ERAS UC a als So Cae oo Ll aie oa aan wel 35 Pee romanian es paragi teed ih. a6 ode ok an ee es ee se oe 35 Pamees on laryeeiand Ue ./eec 212-25... c2.2- 52,58 5he2 ses AY 36 Pteromalid larval parasite............ eee ite Lig Tc ee 36 LETEGRT? TSE TE IPT SISS EiN ai oe ee eS ng a 2 38 I trea 2 oh cle wile SL Foils ewig eats Se 40 PIS Nm ecw ee ee ee OM oe Oe ota dle eee cbes 4] ee es Se ae oe cee bees «dle 43 5 ral a Puate I. IT. Ill. IV. VI. VII. Vill. IX. ILLUSTRA TRONS. PLATES. Conditions favoring the spread of the alfalfa weevil. Fig. 1.— Volunteer growth of alfalfa on vacant lots in Salt Lake City, Utah. Fig. 2.—Volunteer alfalfa growing along the right of way of the Oregon Short Line Railway, a short distance north of Salt Lake eared? : mee i he , coe aa , it ul = : : a a e ‘ Na ‘ S & ? ' t 4 a - 7 yas = 4 f ‘ { ’ E ‘ i 1 , ¥ h F i { a = : a os in " 4 Pa COOPERATION OF BUREAU AND STATION. 13 this fund, on April 1 a corps of entomologists was sent to Salt Lake City, Utah, for the purpose of. carrying out a thorough study of the insect and its ravages, with special reference to methods of control. Gradually other assistants were detailed, until the number employed in and about Salt Lake was increased to nine, exclusive of the student assistant detailed from the State Agricultural Experiment Station. The primary object of this work was, so far*as possible, to restrict the insect to the area it then occupied and to use every effort, by field experiments in measures of control, to devise means of lessening its destructiveness. In the meantime it has been learned definitely that the alfalfa weevil was largely held in check in its native home by its natural enemies. Mr. W. F. Fiske, in charge of the Gipsy Moth Parasite Laboratory, having been detailed for work in Italy, kindly volunteered to look into the matter of natural enemies of the weevil and, so far as was possible without interfering with his other duties, to send over to this country any insect enemies that seemed to him susceptible of colonization in Utah. The object of this was to get these insect enemies established, in so far as it was practicable to establish them, at the earliest possible date, in order that they might have the oppor- tunity to diffuse themselves during the spring of 1911. The value of Mr. Fiske’s services at this time and in this direction can hardly be overestimated. A more detailed account of this matter will be found under a discussion of the introduction of the natural enemies of the alfalfa weevil. Very naturally the alfalfa weevil work divided itself into two branches: (1) The field work, which included all mechanical! measures for controlling the pest in the field; and (2) the work, necessarily carried out largely in the laboratories at first, involved in the care and management of the parasitic material dispatched by Mr. Fiske from Italy. After the beginning of the fiscal year 1911-12 the experi- ment station was able to add but slightly to the force of investigators. By this time, however, the annual generation of the weevil had devel- oped to the adult stage and laboratory investigations had largely decreased. While, as shown, the experiment station, owing to circumstances not under its control, was not able to put into the field men trained _ for this kind of work, the bureau was able by the aid of the imme- diately available fund to overcome this difficulty. In the meantime, however, the experiment station did its full share in other directions. Dr. Ball, director of the station, did not hesitate to use his personal and official influence whenever and wherever it could be of service in advancing this work. Besides this, in a great many cases he was able to relieve the bureau of expenses of field investigations as well as to carry a number of other items of expense for which it would 14 PRELIMINARY REPORT ON ALFALFA WEEVIL.. have been impracticable for the bureau to have provided. It may be stated, then, that from April 1 to September 1, 1910, the coopera- tive work was largely under the direction of Prof. E. G. Titus of the experiment station. From September, 1910, to April, 1911, it was mostly carried on personally by Mr. C. N. Ainslie. During the spring and summer of 1911 the investigation was carried on under the general direction of those connected with the Bureau of Ento- mology. Outside of the work on parasites, which has been carried on wholly by the bureau, it is not possible distinctly to indicate just what part of the cooperation was carried on by either the bureau or the experiment station. This combination has been for the purpose of accomplishing the greatest amount of good, and there has been no inflexible line separating the work of the two cooperative bodies. As a matter of fact, the results obtained could not have been secured under any other arrangement or with less unselfish feeling than has existed among those engaged in the investigation. COGPERATION WITH OTHER BUREAUS OF THE UNITED STATES DEPARTMENT OF AGRICULTURE. Observations made by Mr. W. F. Fiske in the vicinity of Naples, Italy, during the spring of 1910 appeared to indicate a possible preference on the part of the alfalfa weevil for certain varieties of alfalfa. Those varieties, notably, having a slender stem appeared to be less freely attacked as compared with those varieties having more robust stems. It was with the view of perhaps being able to find a variety of alfalfa more or less objectionable to the alfalfa weevil that a cooperative experiment was taken up with the Bureau of Plant Industry. VARIETY EXPERIMENT. _ The Chief of the Bureau of Plant Industry, therefore, detailed Mr. Roland McKee, of the Office of Forage Crop Investigations, to super- intend the seeding of a number of varieties of alfalfa (Medicago - sativa) and the following closely related species: Medicago falcata L., M. ruthenica (L.) Trautyv., MW. lupulina L., M. cilraris (L.) All., echinus Lam., M. hispida nigra (Willd.) Burnet, MW. hispida confinis (Koch) Burnet, M. hispida terebellum (Willd.) Urban, MZ. muricata (L.) All., M. orbicularis (L.) All., and MM. scutellata (L.) Mill. The tests of these varieties are being conducted on a farm in the vicinity of Salt Lake City, Utah. Such observations as it has been possible to make upon the young plants involved in this experiment will be found recorded under food plants. It will of course be understood that the most valuable and decisive information bearing upon the relative extent of attack in these different varieties of alfalfa can not be observed until the spring of 1912. Therefore the information now given must be regarded as only initiative, DESCRIPTION AND SEASONAL HISTORY. 15 INVESTIGATIONS OF VERTEBRATE E\NEMIES. _ In order to determine what assistance might be expected from birds and other animals besides insects, arrangements were made with the Biological Survey to send an assistant to Salt Lake in order to carry out extended investigations along this line. Mr. E. R. Kalmbach was detailed for this work by the Chief of the Biological Survey and proceeded to Salt Lake, Utah, making continuous observations there from May 7 to July 5, 1911. It is not possible at the present time to give the results of this work in detail, but a list of the vertebrate enemies observed attacking the alfalfa weevil will be found under the heading Natural Enemies. THE INSECT NOT CORRECTLY DETERMINED. In the bulletin of the Utah Experiment Station, to which reference has already been made, the name of the insect is given as Phytonomus murvnus Kab., and this name was also applied to the same insect by the writer in Circular No. 137 of the Bureau of Entomology, issued April 20, 1911. It had been so determined by one of the best American authorities on this order of insects. It has, however, | proved to be a closely related insect (Phytonomus posticus Gyll.), much more common and injurious to alfalfa in Europe, western Asia, and northern Africa, and in these countries known generally as _ P. variabilis Hbst., meaning literally the variable Phytonomus. - It is, however, less destructive in the Eastern Hemisphere than it bids fair to be in this country, because of its natural enemies at home, which, as it pepe were not brought over with it when it was Ae introduced. APPEARANCE OF A SECOND SPECIES IN UTAH. A much larger species, Hypera punctata Fab. (fig. 2), the clover- leaf weevil, has recently been found about Malad, Idaho, by Mr. _H.T. Osborn, and about Ogden, Utah, by Mr. E. J. Vosler, both of this bureau. This is a larger insect than the alfalfa weevil, but may be confused with it by the ordinary farmer. It had not before been observed between the Rocky Mountains and the Cascades. While known as a clover insect, this last beetle did some damage to alfalfa in Virginia during June, 1910. DESCRIPTION AND SEASONAL HISTORY OF THE ALFALFA WEEVIL. The fully-developed alfalfa weevil, Phytonomus posticus Gyll. (fig. 1), is a small, rather insignificant appearing beetle, slightly under one- fourth of an inch long, of a brown color, mixed with gray and black hairs arranged in indistinct spots and stripes on the back, as shown in figure 1. Rubbed individuals may be very dark, verging on black, 16 PRELIMINARY REPORT ON ALFALFA WEEVIL. ‘The beetles pass the winter hidden away among matted grass or other similar vegetation, including alfalfa, and, indeed, among most kinds of rubbish anywhere, wherever they will be protected from the weather. The beetles have also been found in early spring under clods and about the crowns of alfalfa plants where the ground had been roughly cultivated the previous autumn. The overgrown mar- gins of fields and irrigation canals and ditches afford excellent places for hibernation, some of which are shown in Plate II, figures 1, 2, and 3. With the first warm weather in spring the beetles become active and diffuse themselves over the alfalfa fields, feeding upon any living part of the plants that have escaped the win- ter or, as soon as it commences to push forth, on the fresh erowth, both leaf and stem. During some years the beetles are abroad in the fields in Utah early in March; in other and colder springs it may be April before they bestir themselves. Latitude and elevation, with the consequent modi- fications of tempera- ture, will have much to do in deciding the — time of emergence from winter quarters Fic. 2.—The clover-leaf weevil (Hypera punctata): a, Egg; 6, b, b, b, inspring. Thev also to larvee feeding; f,cocoon; i, beetle; k,same, dorsal view. (6, /,i, Natural size; k, enlarged; a, greatly enlarged.) (From Riley.) SS extent hibernate in the alfalfa fields. As soon as the beetles have spread from their winter quarters out over the fields they pair, and the females are ready to deposit their eggs (figs. 3,4). As a matter of fact, however, pairmg has been observed in the fall, and females taken while hibernating are ob- served to lay 75 per cent of fertile eggs. According to the notes of Mr. Fiske, made in Italy, they may place their eggs in the old, dead, overwintered stems or even in the dead stems of plants other than those of alfalfa, but in Utah the beetles refused to oviposit in dead stems in the laboratory cages. According to Dr. Giovanni Martelli, at Portici in 1909 the first adults which he obtained appeared toward 1 First contribution to the biology of Phytonomus variabilis Herbst. Bollettino del Laboratoria di Zoo- Jogia Generale e Agraria della R. Scuola Superiore d’Agricolturg in Portici, vol. 5, March, 1911, Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE II. x re “ Se PATS et Ae nt a Fics. 1 and 2.—Hibernating places of the alfalfa weevil along fences and borders of fields in the vicinity of Salt Lake City, Utah. (Original.) Fig. 3.—One of the main irrigation ditches in the Salt Lake Valley, a favorable hiber- nating place for alfalfa weevils. Photographed July 7, 1911. (Original.) HIBERNATION OF THE ALFALFA WEEVIL. DESCRIPTION AND SEASONAL HISTORY. aa the end of April; at Acicastello in 1910 they appeared during the first part of the second half of April. The maximum birth at Portici in 1909 took place toward the end of the second decade of May and the last adults were hatched near the end of May. At Acicastello the maximum birth took place in the first decade of May and the last were hatched during the second decade of the same month. The females do not, however, always confine themselves to alfalfa stems in ovipositing. On April 18, 1911, Mr. T. H. Parks found, eggs of Phytonomus in punctures similar to those made in alfalfa in the stems of the ground plum, Astragalus arietinus. Later Mr. C. N. Ainslie found a number of these eggs in similar punctures, also in the stems of this plant, there being usually six or eight eggs in each puncture. Afterwards Mr. Ainslie found larve feeding on Astragalus utahensis. A few days before, Mr. Parks had also found eggs deposited on the surface of leaves, on bits of trash, on the inside of a split stem of grass, and, in one case, upon the bare ground. In a very early spring some of the eggs may be deposited outside of the plant, but evidently this is not usual and occurs mostly when the erowing stems of alfalfa are too small or not suffi- ciently numerous to satisfy the requirements of ,.. 5 ghe alfalfa weevil: the females in this direction. In preparing for Eggs. Greatly enlarged. egg deposition the female punctures the stem thors Mustation-) with her beak. The punctured stems and a group of these eggs in place are shown in figure 4. The method of oviposition has been described by Mr. Titus.t Observations were made by Mr. C. N. Ainslie in which he found that oviposition seemed to be accomplished by forcing the beak into the fleshy tissues of the stem, sometimes into a hollow stem, in which case the eggs are merely placed in the natural cavity. Where placed in a leaf petiole, as is sometimes the case, the cavity for the eggs must be necessarily eaten out. Generally in these eaten cavities only 4 or 5 eggs are placed, while in the hollow stems 15 or 20 seem not uncommon. Once or twice Mr. Ainslie found eggs placed below the enlarged base of the petiole. In this case the eggs were placed in position through a hole made through the base of the petiole and the mass of eggs was well protected by the hairy leaf buds and unfolded leaflets behind the base of the petiole. Once in a while the hole into the stem is eaten and the beak not merely forced in, in which case the gleam of the yellow eggs can be seen through the tunnel into the stem. When the opening is forced it is left more or less filled with fibers that have been disrupted or forced aside by the beak and the ovipositor. These fibers are often blackened from 1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp. 38-39, September, 1910. 26200°—Bull. 112—12——-2 18 PRELIMINARY REPORT ON ALFALFA WEEVIL. some cause, perhaps simple oxidation, and appear quite different from the ‘‘feeding holes” that aremuch more common. These latter are either saucer or cup shaped cavities eaten into the plant stem or punctures through the epidermis that are enlarged inside the stem. In one alfalfa stem Mr. Ainslie found 4 egg “‘nests,”’ the holes being in pairs. These pairs were one-half to three-fourths of an inch between the separate holes, and each pair was in a separate node, the pairs perhaps 3 inches dis- ' tant from each other. There must have been 30 or 40 eggs at least inthis onestalk. It was picked from a vigorous crown growing beside a ma- nure pile, and nearly every other stem in this crown con- tained eggs. These shoots were tall and had evidently grown rapidly. Indeed this seems to be the kind of stem chosen by this imsect in which to place the eggs; shorter, woodier stems seem seldom to be selected for this Ne wi ° As observed by Messrs. Wilson and Parks, assistants of the bureau, the female beetle, after excavating the cavity for the eggs, inserted her ovipositor and laid a number of eggs before re- moving the ovipositor from the cavity. After this she \ began beating it up and down ~ rapidly over the puncture as Fic. 4—The alfalfa weevil: Larv= attacking a sprig of though pounding the orifice, alfalfa, and ess, in situ; larva, enlarged, at right. sometimes but not always Con’ tere ore excreting a drop of watery material overthepuncture. This secretion when hardened appeared to seal the opening. In some cases the arrangement of the eggs in rows on each side of the puncture, as described by Mr. Ainslie, was verified. Mr. Titus has described the egg * as being oval, rounded at the ends, and when first deposited lemon-yellow in color. As the eggs incu- bate they become darker at one end and a deeper yellow in the other : Bulletin 110, Utah Agr. Coll. Exp. Sta., p. 34, September, 1910. DESCRIPTION AND SEASONAL HISTORY. 19 portions. Under the microscope the surface of the egg is very slightly roughened and sculptured. _ Mr. Ainslie, who made a careful study of the egg (fig. 3) at oviposi- tion and later, found that at time of laying the egg was a mere sac, the shell being little more than a transparent, homogeneous envelope or membrane. As segmentation proceeded this membrane became very faintly pitted, and under the microscope with proper illumina- tion barely discernible reticulations, both pentagonal and hexagonal, were apparent. Both ends and sides seemed equally reticulated, the areolation being perhaps a little smaller at the ends. After the larva emerges the shell that remains is a transparent structureless mem- brane with no trace of reticulation. The number of eggs placed in a cavity varies greatly, there some- times being not more than 2 or 3, ranging up to over 30; probably 10 would be about the average number, although these figures are of course only approximate. Mr. Parks found that during the first half of April the number ranged from 3 to 18, averaging 7 or 8; during the last half and early May the number increased, 25 or 30 being the maximum, with an average of 8 or 9. With reference to the number of eggs that may be deposited in a single alfalfa plant, the one shown beside the hat in Plate I, figure 1, examined on April 23—at which date oviposition was still in progress and the beetles preparing for Oviposition were still exceedingly numerous in the fields—indicated that this plant at this date contained nearly if not quite 1,300 eggs. Of course, in fields where the alfalfa grew up thickly there would be a relatively less number per plant, but these figures serve to illustrate the origin of the countless myriads of larve that swarm over the _ plants in an alfalfa field and render more easy of comprehension the destruction shown in Plate III, figure 1. The difference between - uninjured and affected plants is shown in Plate ITI, figure 2, a and 6. Other ravaged fields are shown in Plate IV, figures 1 and 2, in con- trast with figure 3 of same plate. In the Salt Lake Valley oviposition has been found to take place earlier on the bench lands than lower down in the valley itself. Eec-LAyInG PERIOD. The period of egg laying is a matter of considerable significance, _ since in some degree it will decide the question of efficiency or prac- tical measures of control. As is usual with insects, after a female has exhausted her supply of eggs she dies and there is no second depositing of eggs by her during that season. The actual time required for the individual female to deposit her supply of eggs is of course influenced by the weather. In 1909 egg laying began in the fields early in April, and eggs were found in greatest abundance during | _ the last of May and the first of June. In 1910 egg laying began early 20 PRELIMINARY REPORT ON ALFALFA WEEVIL. in March and was at its height by the middle of May, and Mr. C. N. Ainslie found eggs in a rearing cage where beetles were confined indoors as late as October 22, and others found them as late as Novem- ber 10, and Mr. E. J. Vosler on December 6, while larvz of all sizes were found rarely in the fields November 1. On this latter date the sexes were pairing in the fields and some of the females contained apparently mature eggs, but none could be found deposited in the fields. In 1911 Mr. Urbahns found eggs and very young larve March 31, and adults active in the field on a warm day (January 31, 1912); one feeding and one pair mating. The time required for the eggs to hatch after being deposited is, according to Mr. Titus, from 7 to 16 days, as observed by Mr. Ainslie about 10 days, and according to Mr. Parks’s observations about 13 days. The three series of observations were made during different years, 1909, 1910, and 1911, and, of course, under different tempera- ture conditions. It would seem as though more or less pairing is done in very late fall and the eggs deposited the following spring. Of course, the scattering eggs and larve found throughout the late summer and fall have little economic importance except to indicate what might be expected in more southern localities, although even in Utah some eggs probably survive the winter. EVIDENCE OF A PARTIAL SECOND GENERATION. The occurrence of larve up to the approach of cold weather in late “fall has already been noted. Some of these at least might be ac- counted for from the fact that overwintering females still contaming eggs are found throughout July and early August; but that others of these larve are the offspring of parents developing during the pre- ceding spring is strongly indicated by the fact that the females depositing eggs from which larve afterwards hatch are in perfect condition, unrubbed, and apparently fresh. Under date of October 19, 1910, Mr. Ainslie found that eggs were being deposited in his rearing cages, dropped at random on stems and leaves and even on the sides of the cage, but in no case did he observe them placed within the stem. There were in this cage 150 adults, some of which were undeniably trim and fresh as though they had just emerged, while others were pretty well worn, and there were all intervening gradations. Adult females swept from alfalfa No- vember 2 were found to have oviposited two days later. Adults taken from the fields November 7 and kept indoors were found to have deposited eggs within 2 or 3 days prior to November 30. During the season of 1911 it was possible still further to substan- tiate the foregoing by an extensive series of observations carried on by several of those engaged in the investigation, and besides to add even more evidence that some of these late-appearing larve are the ; Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PEATE Tie Fig. 1.—One of the worst infested fields in the Salt Lake Valley, showing injury to the first crop of alfalfa, which was left uncut. Photographed June 26, 1911. (Original.) Fic. 2.—a, Bunch of alfalfa uninjured by the alfalfa weevil. b, Bunch of alfalfa badly injured by the alfalfa weevil, showing growth made by first crop in the badly infested fields. Photographed June 20, 1911. (Original.) INJURY WROUGHT BY THE ALFALFA WEEVIL. hotographed ie Photographed p she oo fa to Ls hy Bi tot on ch pd alee © Li om | S| req} on a =| he wy rel to to) fel oo | | o he tym bp = fad jet iv | Y Je “ bea ne) hay et ts = be et io] secured Sith-@~ = 3.—First cutting ~v IN DESCRIPTION AND SEASONAL HISTORY. | offspring of parents developing during the preceding spring. Eight apparently fresh adults taken from the field on August 18 by Mr. Urbahns were observed on the 21st to have oviposited to the number of about 20 eggs, in confinement. Nine additional eggs were found on the 23d. August 29, 10 adults, also seemingly fresh and un- rubbed, were confined in a glass vial, and the following day about 50 eggs were found in the vial. Under the same date 112 beetles, supposed from appearances to belong to the spring generation, were collected by another member of the force at an elevation of about 7,000 feet, and the following day 75 eggs were found in the box in which they were confined. Under the artificial conditions not all of these eges hatched. This state of affairs continued and was observed by several of the men to occur up to the end of the season. While the beetles go into hibernation in nearly per- fect unrubbed condition, they emerge in spring with scales and pubescence removed to such an extent that they are almost black in color, smooth, and shining. This appearance so contrasts with that of the newly- emerged adults of the new generation that the latter can be easily separated at sight, and it was these latter that were again and again observed to oviposit and their eggs to hatch out larve. Fig. 5.—Theal- falfs weevil: THe LARVA. Larva. Much enlarged. The larval stage is shown in dorsal view in figure 4 and = (Author's il- . - : : . : lustration. ) in lateral view in figure 5. It is during this stage that ~ the pest accomplishes the greatest destruction, although the beetles are of themselves capable of ruining the second hay crop of alfalfa. Mr. Titus ' states that soon after hatching from the eggs the larve, which at that time are quite active, begin feediug in the interior of the stalk, sometimes remaining there for 3 or 4 days, and isolated examples have been found that have passed into the second stage, still inside the stalk. Larve have been found inside hollow stems several inches away from the place where they hatched, working their way upward, and later issuing through a feeding puncture. Usually after 3 or 4 days they come out and work their way up the outside of the stems and conceal themselves in a leaf bud, usually at the tip of the plant. - That the very young larve are capable of traveling considerable distances to reach their food supply is not only indicated in Mr. Titus’s published statement, but emphasized by the observations of Mr.C.N. Ainslie under date of April 28, 1910. The actions of newly hatched 1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp.39, 40, September, 1910. 99 PRELIMINARY REPORT ON ALFALFA WEEVIL. larve, as observed by him; were remarkably vigorous, very young ones exhibiting great energy as travelers. Their mode of progression is to reach forward and then, with a slight hump, to bring up the rear part of the body. The head is at once thrust forward again. About one move is made per second, and three propulsions will carry the body forward 1 mm. When in doubt as to the direction to be taken, the larva elevates the head and swings it from side to side until some decision is reached, when the journey is resumed. The larve are positively phototropie. _ After working their way upward on the alfalfa stems the larve begin to feed close down between the opening buds on the unfolding leaves. Their manner of feeding there, as observed by Mr. Ainslie, was by scraping off the epidermis with a sort of burrowing motion, leaving only the veins and fragments of uneaten tissue. This selec- tion of the terminal buds may be in part due to the shelter offered as well as to the more tender and succulent nature of the plant growth. Large numbers of young larve may, however, be found feeding among the unfolding buds without being easily seen. This feeding is further described by Mr. Titus‘ as follows: In feeding, the larve bore holes into the buds [see fig. 4], working their way in until they are often completely concealed inside the opening bud. The plant then sends out other buds below this point, and usually other young larve are present to destroy these, so that at times the growing tips of the plants become so injured as to cive these tips the appearance of a gall. As many as 15 young larve have been found feeding in the terminal bud of one stalk. Sometimes, before they are fully developed, in the second stage, they pass out onto the leaves, at first eating the upper epidermis only. The larve, after the usual habit of those of the genus to which it belongs, either-cling around the edge of the leaf or feed in a curved position. This continual eating off of the fresh growth keeps the alfalfa so reduced that it does not produce a first crop. Seriously affected fields are shown in Plate III, figure 1, and Plate IV, figures 1 and 2, while a field that has not suffered from such attack is shown in Plate IV, figure 3. From these illustrations a good idea of the damage done by the larve to the first crop of alfalfa may be obtained. LARVAL PERIOD. From about 5 to 8 days after hatching from the egg the skin of the larva splits and the old skin is pushed off, leaving the larva in a new dress. This process is repeated after a period of from 12 to 20 days and again after about 12 to 30 days, as observed by Mr. Titus. Mr. Ainslie in some instances got pup in 18 to 20 days during May, 1910. These variations in time are probably largely due to tem- perature, which again may be due in part to elevation. 1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp. 40-42, September, 1910. DESCRIPTION AND SEASONAL HISTORY. 93 When the larva is fully grown, it ceases to feed and seeks out some place in the crown of the plant among the litter and trash or on the ground among similar material, where it spins a cocoon (fig. 6). CocOONING AND PUPATING. The cocoon is composed of fine white threads and the construction by the apparently blind larva was in part observed by Mr. Ainslie, who describes its movements as follows: A larva was seen moving about in its snow-white, almost transparent, gauzy, unfinished cocoon. It proved to be spinning a closer mesh from within. Instead of spinning the silk from a gland that opened into its mouth, as was supposed, the fluid from which the silk is made is taken into the mouth apparently from a gland in the caudal segment. The larva applied its mouth to an opening or gland close to the anus, appeared to move its jaws slightly, and then, with a quick movement of the body, was: straightened out as much as possible in its confined space, and instantly the head was applied to the inner network of the cocoon. A slender glistening thread was seen leaving the mouth, being attached glutinously to each thread that it crossed. The larva worked rapidly and nervously, nearly always car- rying its new thread in a rather straight line. From 30 to 50 seconds were required to discharge a single mouthful supplying thread for one-third or one-half a revolution re. 6.—The-alfalfa weevil: Cocoon. inside the cocoon. Much enlarged. (Author’s illus- When all the supply was exhausted, the arg head groped aimlessly about for a few seconds, then was applied to the caudal gland as before. The body would then straighten with a quick movement and almost instantly the thread would be again flowing as before. The new thread was guided skillfully across the meshes, rarely if ever following the line of a thread already laid. A very slight jar would cause a sudden halt for perhaps half a minute, then the opera- tion would hesitatingly proceed. As the irregularly oval cocoon is too small in any diameter to allow the larva to straighten out, the larva moved about by thrusting its small head into a mesh, swinging the body into the desired position; the head would then be moved to another mesh and the operation repeated. The fluidity and amount of the silk must vary as spinning progresses, the silk becoming more viscous or less copious as the cocoon approaches completion. The pupal period, according to Mr. Parks’s notes, during the middle of May lasts about 9 days, the larve spinning their cocoons about 5 days before pupating. (A pupa is shown in fig. 7.) At the end 24 PRELIMINARY REPORT ON ALFALFA WEEVIL. of the season, however, during August, when the temperature is higher, the pupal period averages only 3 days, the cocoon being spun only about 36 hours before the larva pupated. The adult leaves the cocoon about a day after transformation, and unlike others of this genus does not devour the cocoon. Although the insect has passed through its transformation from egg to adult the injury it causes is by no means ended. The beetles them- selves not only feed upon the young growth (fig. 8), but gnaw off the bark of the stems, and, together with the larve still in the fields, in this way prevent the alfalfa from springing up for weeks after the first crop of hay has been removed. Two of such fields are shown in Plate V, figure 3, and Plate VI, figure 3, the ground being almost as bare of growing plants as in figure 1, Plate VIII, where the ground has been eee hci torn up with aspring-tooth harrow. The beetles some- Much cnlarg-a. times cluster in great numbers upon a single plant, as (Author's illus- jilystrated in figure 8. tration.) FOOD PLANTS. In a series of experiments carried out by Mr. P. H. Hertzog, larvee of Phytonomus posticus were placed in cages on various food plants, both alone and with alfalfa, and it was found that they fed freely upon the following plants, in combination with alfalfa: Sweet pea, Lathyrus odoratus; Utah milk vetch, Astragalus utahensis; string bean, Phaseolus vulgaris; obtuse-leaved vetch, Vicia sp.; narrow-leaved vetch, Vicia sp.; white clover, Trifolium repens; red clover, T. pratense; alsike clover, T. hybridum; yellow sweet clover, Melilotus indica(?); whitesweetclover, M.alba; Medicago lupulina; M. echinus; M. hispida nijra; M. hispida confinis; M. hispida terebellum; M. muricata; M. orbicularis; M. scutellata; black locust, Robina pseudacacia; fenugreek, Trigonella fenumgrxcum. The following is a list of plants eaten by the larvee when no other food was offered, but refused when offered together with alfalfa: Hedysarum mackenzii; Astragalus oreophilus; downy lupine, Lupinus; sp. chick pea, Lathyrus sativus; Vicia Fic. 8.—The alfalfa weevil: Adults atropurpurea; Vicia dispema; spring vetch, Vicia sativa clustering on ant == ae r ey ts ; alfalfa. About natural size. (Au- alba; hairy or winter vetch, Vicia villosa; spider plant, _thor’s illustration.) Cleome serrulata. The following plants were refused by the larve even when no other food was offered: Everlasting pea, Lathyrus latifolius; round-leaved mallow, Malva rotundifolia; birds- knot grass, Polygonum aviculare; garden pea, Pisum sativum; lamb’s-quarters, Cheno- podium album; purslane, Portulaca oleracea; prickly lettuce, Lactuca scariola, perhaps var. integrata; ground cherry, Physalis longifolia(?); bitterweed, Ambrosia psilos- tachya; bitterweed, Ambrosia trifida integrifolia; rough pigweed, Amaranthus retroflexus. PRELIMINARY REPORT ON ALFALFA WEEVIL. 95 MIGRATION AND DIFFUSION. There are two periods during which the adult insects migrate, more or less aided by the winds and perhaps to a less extent by other agencies. Such as have not hibernated directly in the alfalfa fields become active in early spring and fly about freely, seeking such fields in which to deposit their eggs. This spring migration covers a considerable period of time—about six weeks, as estimated by Mr. Titus. As the females are more or less heavily laden with eggs, however, the flight of the individual is perceptibly shorter than in the second, or summer, migration, the season for which begins early in June and continues for three or four weeks. Another reason for the shorter flight in spring is that the beetles are searching about, not for places of hibernation, but for breeding places. Having found these, they naturally would not go farther unless carried by the winds. In case of a summer flight, however, the conditions are altogether different. This is the season during which most nomadic insects become more widely diffused. At this time the beetles fly high in the air and apparently over long distances. They are also to be observed crawling about in almost every situation, as with the larger species, Hypera punctata, which may be observed wandering aimlessly over the pavements in the midst of large cities. Then, too, they appear to float about freely on the surface of water, and are doubtless carried long distances down stream by the current. We know this is true in the case of irrigating ditches and canals, and it is also true of the larger species just mentioned in case of streams in the Kast. This habit of the beetles in hiding themselves away in any crevice or aperture that will accommodate them doubtless has considerable to do with their diffusion. As a matter of fact, how- ever, it is absolutely impossible to lay down any law that appears to regulate the diffusion of the insect. There are instances where it would seem almost impossible to prevent the distribution of the pest, and yet most careful examination has failed to reveal anything of this sort. For a considerable time after the alfalfa weevil became abundant about Salt Lake and Murray hay was shipped from these points to Ely, Nev. This, too, in the midst of the season, when it would seem impossible to transport hay from these points to its destination without carrying greater or less numbers of the weevil. Notwithstanding this, years have gone by, and during the summer of 1911 two assistants examined the country about Ely most care- fully without finding a single alfalfa weevil or any indications that it had ever existed there. While it is possible to account for the spread of the insect theoretically, we can not as yet account for its diffusion to the northeast into adjacent sections of Wyoming and Idaho. It does not appear to have entered Idaho by way of the Cache Valley, although Mr. Titus found beetles on a coal car at 26 PRELIMINARY REPORT ON ALFALFA WEEVIL. Cache Junction in 1910. It does, however, occur in the Bear River Valley from Evanston, Almy, and Lyman, Wyo., northward into Bear Lake County in extreme southeastern Idaho: Previous obser- vations would indicate that by a natural diffusion the insect has spread a distance of about 30 miles each year. As a matter of fact, the beetles are continually bemg found where least expected, and they have not been found where, judging from their habits, we would feel most confident of their occurrence. ; The most rapid dispersion of the insect during the last two years has been toward the northeast from the original point of infestation in the Salt Lake Valley. Its injury is now noticeable wherever alfalfa is grown in the river valleys east of Ogden to the Wyoming State line and northward to the southern extremity of Bear Lake. It is known to occur, however, as previously stated, as far north as Cokeville, Wyo., and southward to Evanston and Lyman, where specimens were taken during the summer of 1911. This north- eastward trend of diffusion in the weevil must be considered in con- nection with prevailing southwest winds at the time when the beetles are flying, and, in fact, careful search over the newly infested territory seems to render it highly probable that to this cause is due this northeastward diffusion. The finding of individual larve well scattered over Wyoming fields with little or no indications of intro- duction by human agencies, together with the finding of larve in an irrigated valley isolated from other cultivated crops by 35 miles of dry desert country, are conditions hard to explain in any other way than that the south winds of spring and summer have resulted in carrying flying beetles over low mountain ranges to fertile fields beyond. To just what extent the winds are able to carry the adults into new territory is not known, but at any rate migration in other directions has taken place much less rapidly. FIELD EXPERIMENTS IN DESTROYING THE ALFALFA WEEVIL. Several extended series of experiments in destroying the alfalfa weevil were carried out at various points in the infested territory in Utah, but only those that have shown the best results will here be mentioned. Quite naturally, a measure that will destroy a greater or less number of the insects and at the same time encourage the growth of the plant, and is of practical application, will not only be the most attractive one to the farmer but will result in a double benefit. For this reason disking was looked upon as probably offering the best results. It was thought that by disking and spraying a more rapid growth of the alfalfa plants would be secured, and by following this with the use of a brush drag a great many of the larve would be crushed and destroyed. Mr. Ainslie’s observations made in 1910 4 ee ee ee ea ee eee ee Se ae eee” il v FIELD EXPERIMENTS IN DESTROYING WEEVIL. 27 indicate, however, that the brush drag does not destroy as many of the larve as one would suppose, and for this reason some harsher measures have been put into application during the season of 1911. STREET-SWEEPER EXPERIMENTS. The ordinary street sweeper, such as is used in our cities, appears to be a most thorough measure of destroying the pupe. This much was determined by the Utah Experiment Station. A street sweeper (Pl. V, fig. 1) was used in a field on June 22,1911. While examina- ation showed that the result of this treatment, at this time, was to kill most of the larve and pupe, it did not kill a great percentage of the adult weevils, which had already developed in large numbers. It would have been much better had this work been carried out about two weeks earlier; not only the condition of this field but of others in the neighborhood treated between June 14 and July 1 indicated that considerable good had resulted from this treatment even at this late season. On another farm, owned by Mr. Breeze, southwest of Salt Lake City, a field was swept with the street sweeper about the 14th of June with a view of interfering with the work of the weevil. By July 7 the alfalfa in the Breeze field was about 20 inches high with very few weevils present. (See Pl. V, fig. 2.) Twenty days later the alfalfa was 30 inches hich and in full bloom, being ready for the taking of a second crop. Just across the road from this farm was a field where no treatment whatever had been applied against the weevil. In this field the alfalfa plants were only about a foot in height and very much delayed (PI. V, fig. 3). This seems to indicate that as a protection for the second crop the measure has considerable value. The drawback here is in the expense of a street sweeper, although of course where the members of a community club together, or in case of very large alfalfa fields of several hundred acres, the first cost of this sweeping machine would not constitute such an important item. WrrE-BrusH EXPERIMENT. A 13-acre field of alfalfa 7 years old had been disked in the spring of 1910. ‘The first crop of alfalfa was reported to have been reduced to one-half by attack of the weevil. A weevil-collecting machine had also been used on this first crop, but there were still enough of the weevils left in the field to greatly retard the second crop. It was disked and dragged again and a fairly good yield of the second crop was secured. ‘This was also true of the third crop in this same field. On May 15, 1911, there was a good stand of alfalfa in this same field. One irrigation had at this date been applied. The plants were a little over a foot in height, and while at the time, May 15, they were in fairly good condition they were heavily infested with weevil larve. The gathering machine was used twice between the 17th and 98 PRELIMINARY REPORT ON ALFALFA WEEVIL. 25th of May, and observations made at the time indicate that while many of the full-grown larve were collected, most of the smaller ones were left among the buds. On May 29 the field received a second irrigation. The larve at this time were very abundant; the gathering machine, too, had retarded the growth of the plants by breaking off the growing tips and some of the plants themselves had been broken down by the collecting machine. As a result the alfalfa had apparently made little or no growth since about the 22d, and its value as forage was at that time rapidly decreasing. | A wire-brush machine (PI. VI, fig. 1) was constructed by Mr. L. Hemenway by bolting about 30 pieces of No. 8 steel wire 7 inches long between iron clamps on each spring tooth of an old spring-tooth cultivator. The ground was gone over with one of these on June 1, as soon as the hay had been removed. The jumping action of the spring, together with the wire brushes, proved very effective in crush- ing larve and pupe among the stubble. The field was then gone over with a plank leveler, shown in Plate VIII, figure 2, with square iron edges bolted to a plank. June 7, the field received another brushing with the wire-brush machine, which crushed cocoons and larve. By June 13 the second crop in this field had started nicely with very few weevils present. In another field near by no attempt had been made to treat it or to remove the weevil, and this field was taken as a check on the one under treatment. An examination at this time showed that when the former field was in good condition, with few larve, the field that had received no treatment was bare and brown from their attack. On June 22 the second crop of alfalfa on the treated field was about 8 inches high, while the unworked field was still bare and its condi- tion, on June 27, is shown in Plate VI, figure 3. By the 27th the alfalfa in the treated field was about 1 foot in height (see Pl. V1, fig. 2), the stand extra good, and the treatment had seemed to free the field from weeds and other foreign growth. By July 7 the plants were about 2 feet in height, while, of course, both the adults and larve could be found to some extent in this field. July 27 the second crop harvested 2 tons per acre, selling at $9 per ton in the field. The field at time of harvest of second crop is illustrated in Plate VII, figure1. The unworked field, however, was making an inferior second crop, coming just a little in advance of the third crop in the treated field. From the treated field there was also a fourth crop of hay secured. The field was photographed on October 9, 1911, and the yield of hay is illustrated in Plate VII, figure 2. The condition of the check field a few days later, October 12, is shown in Plate VII, figure 3; here the second and third crops were both not only badly damaged, but so delayed in growth of alfalfa that, as shown by the illustration, no fourth crop was secured at all. Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PreATE Ve Fic. 1.—Street sweeper in operation on alfalfa field after first crop was removed. Larve and pup were crushed by the rotary brush. Photographed June 14, 1911. (Original.) Fie. 2.—Second crop ready to cut in the field on which street sweeper was used June 14, 1911. Good stand and good crop. Photographed July 27,1911. (Original.) ar © x Le Fic. 3.—Second crop of alfalfa growing on field where no treatment was given. Crop short and about two weeks behind that of the field shown in figure 2. Photographed July 27,1911. (Original.) FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL. Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VI. Fig. 1.—Wire-brush cultivator in operation on alfalfa field after first crop wasremoved. ‘The brushes crush the larve and pupe on the ground at this time. Photographed June 7, 1911. (Original.) Fic. 2.—Second crop of alfalfa growing nicely as a result of treatment given. (See fig. 1, above.) Larve and pup2 were killed, so that second crop suffered only slight injury. (Original.) Fic. 3.—Condition of untreated fields about June. Photographed June 27,1911. (Original.) FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL. Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VII. Fig. 1.—Second crop of alfalfa, estimated at 2 tons per acre, secured from field treated with wire- brush cultivator. Photographed August 2, 1911. (Original.) Fie. 2.—Fourth crop of alfalfa secured from field where brush cultivator was used. Photographed October 9, 1911. (Original.) : Fic. 3.—Condition of field used as check (PI. V, fig. 3). The second and third crops on this field made little growth and were much delayed, so what would correspond to the fourth crop was caught by frost. Photographed October 12,1911. (Original.) FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL. Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VIII Fic. 1.—Alfalfa field after first crop was removed, severely disked preparatory to application of “‘mudding”’ process against the alfalfa weevil. Photographed June 21, 1911. (Original.) antes PO Fic. 2. Following the irrigation water with a drag, to ‘“‘ puddle”’ the weevils in the mud. Photographed June 22, 1911. FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL. Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IX. Fic. 1.—Second crop of alfalfa in field treated by ‘‘mudding”’ process. Crop growing well and not iit seriously damaged by the alfalfa weevil. Photographed June 10, 1911. (Original.) | Fic. 2.—Condition of untreated fields at time photograph shown in figure 1 was taken. The alfalfa weevils have prevented the second crop from starting. Photograph taken July 10, 1911. (Original.) ss Fic. 3.—Patch of first crop left in field shown in figure 1, illustrating how the larvee were dissem- inated from the first crop into the field where the weevil had been killed by the ‘‘ mudding”’ process. Photograph taken July 10, 1911. (Original.) FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL. FIELD EXPERIMENTS IN DESTROYING WEEVIL. 29 CULTIVATION IN CONNECTION WITH IRRIGATION. For an experiment to determine the value of cultivation in connec- tion with irrigation in controlling the alfalfa weevil a field was selected on a farm belonging to Mr. Hansen, 1 mile southeast of Sandy, Utah, containing 16 acres. The soil was a light sandy loam. Some of the weevils had been noticed in this field in 1908 and also in 1909, while the first crop of 1910 was severely damaged and the second also suffered considerable loss. May 11, 1911, the field was irrigated, the infestation being considered heavy. The first crop was cut during the week ending June 10. The plants were about 9 or 10 inches high and the hay yielded less than 1 ton per acre of very poor quality. This field was again irrigated and the more elevated portion of it worked with a spring-tooth harrow while the surface was still soft from the irrigation. This treatment was repeated and when finished the field had very much the appearance of any cultivated field, little resembling a meadow. (See Pl. VIII, fig. 1.) On June 22, while the land was still soft and muddy, a light irriga- tion was given it, so that the water collecting in the lower portion of the field stood to a depth of 2 or 3 inches. Four horses were hitched to a plank leveler and dragged through this mud, as shown in Plate VIII, figure 2. This thoroughly ‘‘puddled” the weevil in all of its stages beneath the surface. By the 30th of June a second crop was starting very nicely while neighboring untreated fields were being retarded by the continued attacks of the weevil. Ten days later the plants were about 12 inches high with very few of either larvee or beetles present. How- ever, a patch had been left uncut and unworked in one corner of this field and here the first crop of alfalfa was still standing. (See PI. ‘IX, fig. 3, at the right.) There were a great many larve and beetles on this patch, which disseminated themselves into the growing alfalfa where the mudding process had been practiced, destroying a strip about 1 rod in width, clearly shown in Plate IX, figure 3. The second crop in this field, July 10, 18 days after the mudding experiment was carried out, was about 14 inches high. (See Pl. IX, fig. 1.) In a near-by untreated field at ‘ihe same time, four weeks after the first cutting was made, the condition is ‘shown in Plate IX, figure 2. ~ Burninea MACHINE. Several field experiments were carried out with a machine con- structed with the idea of burning over alfalfa fields after the removal of the first crop for the purpose of destroying the weevils in any stage of development remaining in the field. The machine, as shown in Plate X, figure 1, consisted of an iron frame 9 feet square, 12 inches 30 PRELIMINARY REPORT ON ALFALFA WEEVIL. high in front, and adjustable in the rear. The top was of light sheet iron bolted to the frame. Oil was pumped from a barrel in the conveyance to which this machine was attached and forced through a rubber hose into a supply pipe which fed the nozzles and burners underneath. The oil under pressure came forth from the burners as a mist of fire blowing into the stubble and against the ground. The ene cover served to hold the heat se while this oven passed slowly over the surface. In its unperfected state the machine did effective work and offered ideas of value, warranting the construc- tion of more efficient burners. In fields where there was a clean stand of alfalfa stubble this machine did very well in burning vegetation and destroying all insect life above the surface of the ground. Where many weeds, especially dandelions, were present, the insects found protection under the green leaves. Where parts of fields were burned over, the unburned area showed no growth for several weeks on account of the continued weevil attack. The burned area turned green within a very much shorter time. REDUCTION IN QUALITY OF HAY CAUSED BY THE ALFALFA WEEVIL. While studying the alfalfa weevil on various farms in the Salt Lake Valley during the month of April, 1911, it was found that many farm- ers, through a shortage of forage, were feeding the weevil-injured hay of the first crop to their horses. This hay contained so many old cocoons and was so dusty from larval excrement and dead bodies of weevil larve as to render it unfit as feed for horses. On several occasions horses were observed coughing from the effect of this dust. In fact, many farmers consider the first crop from severely infested fields almost valueless as horse feed. On June 12, 1911, at Alpine, Utah, when the new hay from the first crop was fed to work horses these began coughing almost immediately after starting to feed upon this injured hay. The hay contained large numbers of dead weevil larve, some still on the skeletonized leaves and some in the freshly spun cocoons. On September 13 hay from the first crop, in stack’, was examined at Layton, Utah, and found to be very dusty, containing many dead weevil larvee and also pupe. NATURAL ENEMIES. The natural enemies of the alfalfa weevil consist of vertebrates and invertebrates. The former have been studied by assistants of the Bureau of Biological Survey, and a list of species observed to attack the weevil is given herewith. NATURAL ENEMIES. — oo oe The invertebrate enemies are divided between native species and those imported from Italy, the native being largely predaceous and the foreign all parasitic. Besides these, there are two fungous enemies, both of which affect the insect to a greater or less degree. INVERTEBRATES. When a foreign species, like the alfalfa weevil, is introduced into a new country, some time is required for the native insects to find out that it is suitable for food, pre- cisely as man himself would under the same circumstances have to learn what products of a new country were edible. Besides, he would most likely cultivate a taste for some of these things which at first were distasteful to him. Thus it is that native insect foes of in- troduced species begin. slowly Fia. 9.—Nine-spotted lady-beetie (Coccinella 9-notata): at first to prey upon them. a, Adult; b, lerva. Much enlarged. (From Chit- The following native pre- “"*"? | daceous insects have been found attacking and devouring the alfalfa weevil: PREDACEOUS ENEMIES. A species of tiger-beetles,-Cicindela imperfecta Lec., was in one instance observed to feed upon an alfalfa weevil larva in the field. Several other indi- viduals belonging to the same species when taken to the laboratory readily devoured larve. Three species of lady-beetles, Coc- cinella 9-notata, Hbst. (fig. 9), Hip- podama spurra Fig. 10.—Convergent lady-beetle (Hippodamia convergens): a, Adult; b, Lee a and H. con- pupa; c, larva. Enlarged. (From Chittenden.) b vergens Guér. (fig. 10), in the larval stage attacked and devoured half-grown larvee of the alfalfa weevil in the fields. Larve so taken were brought into the laboratory and adults reared, from which specific determina- tions were made. In case of H. spuria the adult was also observed devouring larve in the field. The malachid beetle, Collops bipunctatus (fig. 11), was repeatedly observed feeding upon the weevil larve in the fields. 32 PRELIMINARY REPORT ON ALFALFA WEEVIL. The tenebrionid beetle, Eleodes suleipennis Mann., was accused by farmers of feeding upon the larve of the weevil and when taken to Fic. 11.—The two-spotted Collops ( Collops bipunciatus): Adult. Enlarged. (Origmal.) the laboratory it readily did this in confinement. An allied species, E. suturalis Say, was ob- served by Mr. E. O. G. Kelly to devour chinch bugs in the_ neighborhood | of Wellington, Kans. In the latter imstance the beetles seemed to prefer the partially decaying leaves of corn under which the chinch bugs were hiding. It is prob- able that while these in- sects may devour a few of the weevil larve theyprefer other and vegetable food. The predaceous mite, Pediculoides ventricosus Newp. (figs. 12, 13), was introduced from Indiana in March, 1911, but was afterwards Fic. 12.—Pediculoides ventricosus, @ mite predatory on the alfalfa weevil: Adult female before the abdomen has become inflated with eggs and young. In this condition the mite is nomadic and predatory. Greatly en- Fic. 13.—Pediculoides ventricosus: Adult female after the larged. (Redrawn from abdomen has become inflated with eggs and young. Brucker.) Greatly enlarged. (Redrawn from Brucker.) found a sufficient distance away from the points of introduction to show plainly that it was already an inhabitant of Utah. The results Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PUATE Fic. 1.—BURNING MACHINE EXPERIMENTED WITH AS A METHOD OF DESTROYING THE ALFALFA WEEVIL. (ORIGINAL.) Fia. 2.—BOXES CONTAINING PARASITES OF THE LARVA AND PUPA OF THE ALFALFA WEEVIL, SHOWING HOW THIS MATERIAL WAS IMPORTED INTO THE UNITED STATES FROM ITALY. PHOTOGRAPH TAKEN JUNE, 1911. (ORIGINAL.) Fig. 3.—BoOXES OF PARASITE MATERIAL IMPORTED FROM ITALY WHICH CONTAIN E@a@ PARASITES OF THE ALFALFA WEEVIL. PHOTOGRAPH TAKEN MAy, 1911. (ORIGINAL.) NATURAL ENEMIES. 38 wai experiments with this mite, which is so effective in destroying the jointworm in the East, were unsuccessful, as it was found that the mites would not attack either the larve or the pupz. They fed freely upon the eggs of the weevil, where these were easily accessible, but they seemed unable to gain access into many of the egg masses through the ordinary egg punctures. A single egg did not furnish sufficient food to bring one mite to maturity, and it would therefore necessarily perish; but where there were clus- ters of eggs in contact - with each other, the female mite was able to shift her body about sufficiently to devour more than one egg and was thus enabled to reproduce. Inthefield, when placed in cages with an abundance of eges of the alfalfa wee- vil, the mites appeared to make considerable headway in overcoming the weevil, butin no case could the effects of their attack be traced farther >) \ than 2 feet from the cage ) where they ha d b een Fia. 14.—A predaceous mite, Erythreus arvensis: Adult. Greatly confined in the fields | ee eee _ A little mite (Trombidium) was found attached to the adult weevil beneath the wing covers, and while it was observed quite commonly in late summer and fall, so far as observations indicated it did not appear able to kill the host insect. A predaceous mite, Hrythreus arvensis Banks (fig. 14), was found, by Mr. Ainslie feeding on eggs of the weevil in the egg punctures. The economic value of this species is as yet very obscure. Spiders are occasionally found feeding upon the larve in the fields. Lace-wing flies (Chrysopa) fed upon the larve in confinement when forced to do so, but preferred aphides. They were not observed to attack the weevil in any form in the fields. ~ 26200°—Bull. 112—12-—_3 34 PRELIMINARY REPORT ON ALFALFA WEEVIL. A NATIVE TRUE PARASITE. Only one specimen of a single species of 2 true parasite of the alfalfa weevil has so far been found in America. This was described by Mr. Viereck as Znoplegimorpha phytonomi. It was found August 30, 1911, at Hoytsville, Utah, in the form of a cocooned pupa within the cocoon of the alfalfa weevil. The specimen was picked up from the surface of the ground in a badly infested alfalfa field and the adult parasite reared. The adult emerged September 3. INTRODUCED PARASITES. Several species of parasites were sent over from the vicinity of Portici, Italy, by Mr. W. F. Fiske during April, May, and June, 1911. Fig. 15.—Anaphes sp., 2 mymarid egg parasite of the alfalfa weevil: Adult male; female antenna above at right. Greatly enlarged. (Original.) The egg parasites were obtained by collecting stems of alfalfa con- taining eggs of the alfalfa weevil, placing these in boxes (Pl. X, fig. 3), and transporting them by cold storage on steamers bound for New York. On arrival from Europe they were promptly forwarded by . , ; al 4 | refrigerator express to their destination, Salt Lake City, Utah, where | they were at once taken either to the laboratory at Salt Lake City (Pl. XIII, fig. 1) or to the laboratory at Murray (Pl. XIII, fig. 2). Parasites that attack the weevil after it has hatched and before it has developed to the adult were handled in much the same manner. ~ The boxes in which they, were consigned are shown in Plate X, figure 2. The time required to transport these boxes from Portici, Italy, to Salt Lake City, Utah, was from 16 to 21 days. NATURAL ENEMIES. 35 Ecc PARASITES. There were two ege parasites, one, a true egg parasite developing within the egg, and the second, a parasite the eggs of which are prob- ably deposited in the alfalfa stems among, but not in, the eggs. The larva of the latter is predaceous on the masses of weevil eggs as placed by the female weevil, and among them it develops to the adult. MYMARID EGG PARASITE. A mymarid egg parasite, Anaphes sp. (fig. 15), was found in all of the seven shipments received from Italy. It was received in all stages of development, except perhaps the egg and adult, and was either left in the same aa these being perforated with holes and Fig. 16.—Imported pteromalid egg parasite of the alfalfa weevil: Adult. Greatly enlarged. (Original.) glass tubes inserted (Pl. XI, fig. 2), or placed in specially prepared -boxes (Pl. XI, fig. 3) which were also perforated and had glass tubes inserted. The parasites were reared from this imported material, and from the parent stock two generations were reared on American egg masses of the alfalfa weevil. The third generation, together with others of the first and second generations and natives from later ship- ments, was placed in field reproduction cages (Pl. XII, fig. 3) to the number of about 300. These cages were overstocked with eggs by confining numbers of weevils in them. After about 10 days the covers to these cages were removed, thus allowing the generation of parasites that developed within Gen to escape and scatter freely over the fields. MH PTEROMALID EGG PARASITE. A pteromalid egg parasite (fig. 16) was likewise found in all of the seven importations. The larva (fig. 17) feeds externally on the egg masses in the alfalfa stems, later transforming to the pupa (fig. 18). 36 PRELIMINARY REPORT ON ALFALFA WEEVIL. The disposal and management of this species did not differ from that followed with the preceding, except that some of them were received too late in the season to use in the low valleys because the majority of the eggs of the weevil had already hatched. Owing to this the parasites were taken to places in higher elevations where eggs of Phytonomus were still abundant. Approximately 460 were placed in field cages like those previously mentioned and treated’ in the same Way. controlling the alfalfa weevil in Italy. PaRASITES OF LaRv& AND Pup. The parasites of the larve and pupe of the alfalfa weevil, which were five in number, did not appear in ee ha esa eg ee aries consignments. from Italy and were confined pteromalid egg to the last three received at Salt Lake City May 16 parasite of the alfalfa ,weevil. Greatlyenlarged. boxes (Pl. X, fig. 2), which included only the cocoons ba of the alfalfa weevil. These boxes were especially devised to guard against the accidental Paes of adult insects of any species en route. After being removed from the boxes in which the cocoons were received, they were placed in parasite boxes of the larger type (Pl. XI, fig. 3), where the parasites emerged and were separated from the weevils that had developed en route. Both weevils and parasites on emerging from the cocoons in the box would seek the hght and appear in the glass tubes shown in the illustration, where they were readily separated and the weevils killed. The parasites were. then transferred to glass cages (Pl. XI, figs. 1, 4) which had been previously well stocked with larve and cocoons. PTEROMALID LARVAL PARASITE. A pteromalid parasite of alfalfa weevil larve (fig. 19, female; fig. 20, male) was received in only the later m6 13—pPupa consignments. ‘Thus far it has not been possible to deter- of Ptero- mine the species. In the laboratory rearings, preparatory pea § a to placing the parasites in the field cages, and later, the the alfalfa species was carried through five generations. (Fig. 21, a Gineatiy sch shows the pupa of the alfalfa weevil, with the egg (fig. 21, 5) eae : asit is placed on the pupa; fig. 22 shows the larva, and fig. 23 shows it destroying the pupa of the alfalfa weevil; fig. 24 shows the pupa of the parasite itself.) In order to accomplish this, however, it was necessary to secure weevil larve, as hosts for them, from high Mr. Fiske found this species to be very éffectieta in to June 3. In these three shipments were metal . : Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE Xl. Figs. 1 and 4.—Types of cages in which larval and pupal parasites of the alfalfa weevil were reared in the laboratory. Photograph taken during June, 1911. (Original.) Figs. 2 and 3.—Boxes sealed and fitted with glass tubes into which imported parasites emerged and were separated in the laboratory. Photograph taken during May and June, 1911. (Original.) INTRODUCTION OF PARASITES OF THE ALFALFA WEEVIL. Bul. 112, Bureau of Entomology, U. S. Depi. of Agriculture. PLATE XIl. Fics. 1 AND 2.—FiIELD CAGES USED IN HIBERNATION EXPERIMENTS ON THE ALFALFA WEEVIL. (ORIGINAL.) Fig. 3.—PLANTING A COLONY OF IMPORTED PARASITES OF THE ALFALFA WEEVIL IN UTAH IN AN ALFALFA FIELD. PHOTOGRAPH TAKEN DURING JUNE, 1911. (ORIGINAL. ) NATURAL ENEMIES. 37 elevations and bring these into the laboratory, thus supplying them artificially. There were 230 individuals liberated in field cages, the coverings of which were later removed, and 49 liberated directly Fig. 19.—Pteromalid parasite of larva and pupa of the alfalfa weevil: Adult female. Greatly enlarged. (Original.) 4 %4 a Y Fig. 20.—Pteromalid parasite of larva and pupa of the alfalfa weevil: Adult male. Greatly enlarged, } (Original. ) into the open field. Observations have since shown that this species has actually colonized itself in the field ; whether temporarily or per- manently it remains to be seen. 38 PRELIMINARY REPORT ON ALFALFA WEEVIL. OTHER PARASITES. The following three parasites came mainly in the last two shipments from Italy. The adult of one species (Canidiella curculionis Thoms.) (fig. 25) oviposits in the larvee of the alfalfa weevil in different stages of development, but the offspring therefrom emerge from the cocoon spun by the weevil, the cocoons of the parasite always showing through the meshes of the cocoon of the weevil (see fig. 27). 'Thisspecieshas two generations an- nually and hibernates as cocooned larve. The alfalfa stems Fic. 21.—Pteromalid parasite of larva from which thethree FG. 22.—Pteromalid parasite and pupa of the alfalfa weevil: a, Sige f “e of larva and pupa of the Enlarged pupa of alfalfa weevil with species O parasites alfalfa weevil: Larva. eggs of parasite in place; b, egg, of this eroup were Greatly enlarged. (Orig- greatly enlarged. (Original.) inal.) reared were also in- fested by Apion pisi Fab., and therefore some or all of the group may perhaps also parasitize this latter insect. Owing to its small size, however, as compared to the parasites, this seems rather unlikely- The two additional species reared with the preceding are not definitely determinable, but one is Phygadewon sp., and the other may prove to be Mesochorus migripes Ratz. Of this latter spe- cies Mr. T. W. Wassiljew, a Russian entomologist, under date of Febru- ary 6, 1911, wrote us: I wish to say that I am able to give you only one instance of a parasite having been found, and that was in the vicinity of Tasch- kent (Turkestan), where I noticed in the past year [1910] that over 20 per cent of the larvee of P. variabilis were attacked by an : < Fia. pars of Fic. 23.—Larva of ptero- Ichneumon parasite. Unfortunately I do pteromalid para- malid parasite attack- not know the name of this species of para- __ site shown in fig- ~ oie pi samy site at the present time, other than thatit be- ures 22 and 23. (Original.) ee Jongs to the Ichneumonide. Judging from Oceana the elliptical, thick-shelled cocoon it might : possibly have been Mesochorus nigripes Ratz., which Mr. Ratzeburg (The Ichneu- monide, III, p. 120) gives as a parasite of P. rumicus. All of these parasites resemble each other to a certain degree, al figure 25 will suffice to illustrate them, for the present at least. At the present stage of this experiment in introducing parasites of the jail a al al Pe a . » = NATURAL ENEMIES. 39 alfalfa weevil the possibility of permanent establishment and future efficiency in the case of these species seems rather more encourag- ing than in case of the others. During June, 1911, 40 individuals reared from imported cocoons were placed in field cages artificially overstocked with weevil larve, the cage covers being removed later. Besides this, there is at present on hand a considerable amount of hibernating material (Pl. XII, figs. 1, 2) artificially reared in the Murray laboratory (Pl. XIII, i= 2), ie will be allowed to eo naturally, into the alfalfa falda, Fig. 25.— Canidiella curculionis, a parasite of the alfalfa weevil: Adult female; lateral view of abdomen of same below, at right. Enlarged. (Original.) The parasite Itoplectis masculator Fab. (fig. 26) differs from the preceding by reason of the fact that it pupates entirely within the pupa of its host. It is known to be a primary parasite, but the num- ber so far secured is too limited to warrant any discussion regarding it, or any predictions as to its future in America. Of the eighth and last of these parasites, Hemiteles sp., very little isknown either in Europe or America, and with the obscurity surround- ing its habits it may prove to be either a primary or secondary parasite, a friend or an enemy of the others. It is therefore being handled with the utmost caution, none having been liberated either in the fields or in field cages. 40 PRELIMINARY REPORT ON ALFALFA WEEVIL. VERTEBRATES. During the season of 1911 the Biological Survey, at the suggestion of the writer, kindly detailed an assistant, Mr. E. R. Kalmbach, to study the bird and other vertebrate enemies of the alfalfa weevil, © and the following is a list of vertebrates found to feed on the alfalfa weevil in Utah, as determined by Mr. Kalmbach, May 7, 1911, to July 25, 1911. Wilson’s phalarope, Steganopus tricolor; kKilldeer, Oxyechus vociferus; valley quail, Lophortyx californica vallicola; mourning dove, Zenaidura macroura carolinensis; red- shafted flicker, Colaptes cafer collaris; Arkansas kingbird, Tyrannus verticalis; Say’s Fic. 26.—Itoplectis masculator, a parasite of the alfalfa weevil: Adult female; lateral view of first abdominal segment at right. Muchenlarged. (Original.) phoebe, Sayornis sayus; Traill’s flycatcher, Empidonax trailli; desert horned lark, Otocoris alpestris leucolema; magpie, Pica pica hudsonia; bobolink, Dolichonyx oryzi- vorus; cowbird, Molothrus ater; yellow-headed blackbird, Xanthocephalus xantho- cephalus; thick-billed red-winged blackbird, Agelaius pheniceus fortis; Western mead- owlark, Sturnella neglecta; Bullock’s oriole, Icterus bullocki; Brewer’s blackbird, Euphagus cyanocephalus; house finch, Carpodacus mexicanus frontalis; English sparrow, Passer domesticus; Western vesper sparrow, Powcetes gramineus confinis; Western savannah sparrow, Passerculus savannarum alaudinus; Western lark sparrow, Chon- destes grammacus strigatus; white-throated sparrow, Zonotrichia albicollis; Brewer’s sparrow, Spizella breweri; Western chipping sparrow, Spizella socialis arizonx; desert song sparrow, Melospiza melodia fallax; green-tailed towhee, Oreospiza chlorura; black- Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE XIII. Fias. 1 AND 2.—LABORATORIES OF THE BUREAU OF ENTOMOLOGY, U. S. DE- PARTMENT OF AGRICULTURE, AT SALT LAKE CITY AND Murray, UTAH. (ORIGINAL. ) NATURAL ENEMIES. Al headed grosbeak, Zamelodia melanocephala; rough-winged swallow, Stelgidopteryx serripennis; sage thrasher, Oreoscoptes montanus; Western robin, Planesticus migratorius -propinquus; Rocky Mountain toad, Bufo lentiginosus woodhousi; leopard frog, Rana pipiens; salamander, Amblystoma sp. Funcous ENEMIES. ‘Whenever the larger species Hypera punctata (fig. 2) becomes excessively abundant east of the Mississippi River, myriads of these larve may be observed coiled about the uppermost tip of blades of grass or similar vegetation, where they soon die and become black. These are apparently de- stroyed by afungus, Empusa spherosperma. When investigations of the alfalfa weevil were first undertaken there were great numbers of these dead and dying larve to Paoumndan Washington, D.C.,in Potomac. y¢ 27 cocoon of the alfalfa weovil Park. They were gathered up and sent showing cocoon of the parasite out to Salt Lake City and placed in the Paine MA THs Dro rs. hands of Mr. Ainslie with the hope of in- - - troducing this fungus among the larve of the alfalfa weevil. The experiment appeared to have been a failure, and it was thought that the climate of Utah was too dry to enable this fungus to exist there. Later this larger species was found in Utah, as has already been stated, and during the spring of 1911 the fungus was found in the vicinity of Salt Lake City. Apparently, how-— ever, the fungus does not affect the larve to the same extent that it does here in the East, except after these have -reached their full size and constructed their cocoons. Larve of the alfalfa weevil (fig. 5) and pupe (fig. 7) soon began to be observed in the cocoon (fig. 6) dead and thoroughly permeated: with this fungus. No individuals in any case were found dead excepting within their cocoons. On June 13 in the vicinity of Salt Lake City it was estimated that one-fifth of the cocoons contained dead larve or pup. In the Weber Valley, about Hoytsville, Utah,:on the last of August, it was found that of 580 cocoons examined 258, or 44.5 per cent, were dead, partly at least because of infestation by this fungus. Examination at another point showed that 38 per cent had apparently died from the same cause. To all appearances, then, this was more effective in killing the alfalfa weevil than all other natural enemies combined. NN ——— ———————Eee ee —_— Pe INDEX Page Ainoplegimor pha phytonomt, parasite of alfalfa weevil...............------- At 34 Agelatus pheniceus fortis, enemy of alfalfa weevil.......2....---..-.--+-----: 40 Alialia (see also Medicago sativa). duration of growing which should be allowed in weevil-infested districts. 12 meer ior aileal ey weevil 22% 2:2 tes We eR yee a esse ss Bee sed. 2 1-41 clover-leaf weevil (Hypera punctata).......------------- 15 hay, reduction in quality caused by alfalfa weevil.........---.------- 30 varieties experimented with in relation to alfalfa weevil.--....-..--..-- 14 Beeeslagitl). Gescription and habits: ..--.<-.. 2:22.22. 52502 11-12, 15-17 alhiedispecies miroduced trom Kurope.: :.ss..222..2.22.2..2. Pe vic, fopeatanee of second speeres im Utah. .: 2.52.2 .2s- 222 425----- 15 Cmte BORER CRiO LGM Co 08 0 wee Fase Pais oo le Hens 2 hls 12 Seem Ane TOURING. =o sl Se ei 2d ee. aio deed see 23-28 cooperation of Bureau of Entomdlogy and Utah Experiment eyepiece ee Ree ie Fo alos AIL a at 12-14 with other bureaus of U. 8. Department of Agricul- PME Cee ena se AS ees te oe Seta toe de tes 14-15 Doserimdan and ceasonak history: Jace Piliae de. 2- 2s 25 2. 222% 2% 15-24 Sea ipRa sei RE re tr Es oi. 8 ot te eis ae es bs el 25-26 Semioninoneim- the old: world). 4.2 ..ee8.sse8.edebeseiail: 9 Pare ea ee ae sete IO We. eee Beeb waited ties 12, 17-19 Anne ETO, . ys

: Page. Medicrgo lupulina, experiment against alfalfa weevil. ..... ....2 2a 7m food plant of alfalia weevil... 20S. 8_.:2..:.._ 23 24 muricaia, experiment against alialfa weevil.--...:..........J222 eee 14 food plant of alfalfa weevil.........--- gn s2 2... a orbicularis, experiment against alfalfa weevil....................... Sm food plant of alfalfa weevil...........), 2) ee 24 ruthenica, experiment against alfalfa weevil. ......................- 14 sativa (see also Alfalfa). experiment against alfalfa weevil...-.........-..). ee 14 scutellata, experiment against alfalfa weevil...........-....--22ueeee 14 food. plant. of alfalfa, weevil....<.<..-.... +] 23 24 Melilotus alba, fqgod plant of alfalfa weevil...............:-..-..55- 550 24 indica, food plant of alialia weevils. ..2.--.55.2225e. = eee 4. ee 24 Melospiza melodia fallax, enemy of alfalfa weevil......:.....------.225+.eseeee 40 Mesochorus nigripes, parasite of alfalfa weevil....................-.------ eis 38 Phytonomus rumacis. : . ...-202+.--222 eee 2 38 Molothrus ater, enemy of alfalfa weevil..............-.------ ee 40 Oreoscoptes montanus, enemy of alfalfa weevil. -.:.......:-.---.225332==eeee 40 Oreospiza chlorura, enemy of alfalia weevil....-.....:..2-.-2.-.>. 525 40 Oriole, Bullock’s. (See Icterus bullock.) Oiocoris alpestris leucolema, enemy oi alialia weevil.........-..-.-7 =e 40 Oxyechus vociferus, enemy of alfalfa weevil..-..........--.-..+-)250.==e 40 Passerculus savannarum alaudinus, enemy of alfalfa weevil.............-..--.-- 40 Passer domesticus, enemy of alfalia weevil....-.....--...---2.--s=)==eeeeee 40 Pea, chick, eaten by alfalfa weevil..........---22---:.:5==——n 38 Physalis longifolia refused as food by alfalfa weevil. .............253.===eeae 24 Phytonomus murinus, name incorrectly applied to alfalfa weevil......-......- 15 nigrirosiris, introduction into United States... -...-.- 253 .ueueeeee 9 posticus. (Sce Alfalia weevil.) punctatus (see also Hypera punctata). punctatus Hypera punctata....-. ---- c= =~. + ==) = 25 it introduction into United States ....::. .. 33a 9 rumicis, host of Mesochorus nigripes..-----<+22- +--+ =5se en 38 variabilis, name given alfalfa weevil in old world. ......--------- 15 Pica pica hudsonia, enemy of alfalfa weevil.....--.--------:-::=-25===e 40 Pigweed, rough. (See Amaranthus retroflexus.) Pisum sativum refused as food by alfalfa weevil............------------++---> 24 Planesticus migratorius propinquus, enemy of alfalfa weevil. .....------------ 40 Polygonum aviculare refused as food by alfalfa-weevil.....------------------- 24 Powcetes gramineus confinis, enemy of alfalfa weevil.......----.------------- 40 Portulaca oleracea refused as food plant by alfalfa weevil. .......------------- 24 Pteromalid egg parasite of alfalfa weevil.......-.....----------+---------+---: 35-36 larval parasite of alfalfa weevil......---.---2-+---+0::-----===—ee 36-37 Purslane. (See Portulaca oleracea.) Quail, valley. (See Lophortyx californica vallicola.) 40 INDEX. Robinia pseudacacia, food plant of Sigal weevil av: ese, eee Robin, western. (See Planesticus migratorius propinquus.) Salamander. (See Amblystoma sp.) Sayornis sayus, enemy of alfalfa weevil......... ee se FO ie ed Sheep, pasturing as remedy against alfalfa weevil. ..........-..-..--- Sparrow, Brewer’s. (See Spizella brewer.) desert song. (See Melospiza melodia fallax.) English. (See Passer domesticus.) western chipping. (See Spizella socialis arizon2.) lark. (See Chondestes grammacus strigatus.) savannah. (See Passerculus savannarum alaudinus.) vesper. (See Poewcetes gramineus confinis.) white-throated. (See Zonotrichia albicollis.) Spider plant. (See Cleome serrulata.) pauaerwememes Of alfalia weevil..........-.2---..+-s22+-+--++-e 5-5 pela brewer, enemy of alialia weevil............-.2..2---.2.-- oe socialis arizonx, enemy of alfalfa weevil..........-...-.-.----- Dieganopus tricolor, enemy of alialfa weevil. .........--.-..-.---.----- Stelgidopteryx serrupennis, enemy of alfalfa weevil..............-----.- Siurnella neglecta, enemy of alfalia weevil.......--...--------.--.-.--- Swallow, rough-winged. (See Stelgidopteryx serripennis.) pweeper, street, against alfalfa weevil..........-.-+.../----.-.+------ Sweet pea. (See Lathyrus odoratus.) Thrasher, sage. (See Oreoscoptes montanus.) Toad, Rocky Mountain. (See Bufo lentiginosus woodhouset.) Towhee, green-tailed. (See Oreospiza chlorura.) Trifolium hybridum, food plant of alfalia weevil.................--..-- prearense. 4000 plant of alfalfa, weevil......7-..0..-......-+4- repens, food plant of alfalfa weevil. .......-.-- SE Oe aa oe Trigonella fenumgrxecum, food plant of alfalfa weevil......-........-.-- iirannus verticals, enemy of alialia weevil. ........--.-.----.-.....-- Vetch, hairy or winter. (See Vicia villosa.) narrow-leaved. (See Vicia sp.) obtuse-leaved. (See Vicia sp.) spring. (See Vicia sativa alba.) Utah milk. (See Astragalus utahensis.) Vicia atropurpurea eaten by alfalfa weevil...............-.. “a SERN ete Maeno eauen by aitalia weevil. 2.2. ..32-.0.-.-..2550s51-ese--- mamaiooeeaten by alfalfa weevil. ...-...:..:....-..-..s------- peed plat of alialia weevil.....0......2..+-52.-+--+-+--4-2- fmmentem by alfalia weeval..--....22.-2..5/2.-225--4-20 nse Weevil, alfalfa. (See Alfalfa weevil.) _ Wilson’s phalarope. (See Steganopus tricolor.) imwomen aeainstalialia weevil........--2.-.-.-.0....-. cece eee n eee Xanthocephalus xanthocephalus, enemy of alfalfa weevil....... Zamelodia melanocephala, enemy of alfalia weevil............-.....--- Zenaidura macroura carolinensis, enemy of alfalfa weevil. ..........--- Zonoirichia albicollis, enemy of alfalfa weevil...............-.-..---- O AT Page. 24 40 12 24 24 24 24 40 Government Printi .C.,at locents percopy . 2 | | i eee . ye ; 3 : ? ett, A . | A ; yl Sa I] 7298 | . ered | z | Fe ga caren Pee | | | tae | m +7 oy ee Fe ‘ ' : | reas AC : | | been | + ad " . x y . > ne a? a r i : ~ ; - ~ - ‘ ‘ ’ me ¥ 1 - a ny . i P - i 5 sy \ el ot + { e a ; ‘ \ % . : ‘ { ¥ a P) ’ . ' ~ ’ 1 7 ane > we ‘ 4 A oo Fete rane ae he fae 2 te ea eee RarPar sAacsRAMie i, 8 cp lO Aten. 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