SS adh sede One? ans wee pae dain <> vii vere hs od : Oe a lia ee ; vy view . J J . cvs : revere: . . lanen es < wtb at oh (ata . : - 4 ¥ Ter eve wer > eer ewiv Se gi . ‘ 2 Pete ee Wort > ew ¥ ' " ad a , Sa. ) Y veer drveemnexh : c - ’ et: 4 r rota 2 roca perth Ls nds Ath phates . : ~<- “a near 7 - on we ’ wes ye pated deci 5 i WE 9 ee wre eV re rEerey PUNT PERV Tews ee edd ’ ~ — fee - “ . " ‘ © ¥ ¥ li ‘ z t ° ; 7 - ° as ae ‘ soa : é ~ et aay ; <> SO OF Or Soy ; ; ‘ . - vivve yw wrt Per? oF preteens en : had - 4 oes ‘ CPOE? Fwy eee wwe ve pada itt EA EPL “2 Sr rnge dp a Sedans . oy es : e — OP eer he sve Yair vee rye < lied "¥ Oe ee * VET ET LY EY? vvererewey e's e yw’ vr se ted . s¥ sur eS eee I > vY « Te Ve wets ere er ied VT Wwe Vw wee “r | Siw ty pert | |e | “ e “el a m i | Reh oo wr wy ALTE . “\ | bbl f Ly Ped : | ~ | . | , i pehet pepe leh a cbehlk |_| 3 | ba 4 ress. Pe ee eee tee oy y = Bs ta ‘ rey : A | iano. wee : Se iy ct sy TP HaTE ~ Serer ~ = cow 1 ve ~~ Jur | | es ~ : ‘ } ww a wi nr aoe SY soot a | r | aq] : pd WS seus We uli paineaiaaae ss erin ae VU Vee Jj disubl Nt ' / bs } “iw ws 4 sod © ae eo Tal - BUREAU OF ENTOMOLOGY—BULLETIN No, 106. ~ (08, 1Q1I~-1d NEZO. HOWARD. Entomologist and: Chief of Buran: : THE LIFE HISTORY AND BIONOMICS OF SOME NORTH AMERICAN TICKS. ( BY W. A. HOOKER, F. C. BISHOPP, anp H, P. WOOD. UNDER THE DIRECTION OF W. D. HUNTER. IssurD SEPTEMBER 7, 1912. 2ZA0Tb4 WASHINGTON: GOVERNMENT PRINTING OFFIOE. 1912, wry U. 5. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 106, L. O. HOWARD, Entomologist and Chief of Bureau. THE LIFE HISTORY AND BIONOMICS OF SOME NORTH AMERICAN TICKS. BY W. A. HOOKER, F. C. BISHOPP, anp H. P. WOOD. UNDER THE DIRECTION OF W. D. HUNTER. IssuepD SEPTEMBER 7, 1912. iA, rah a LS aap Pee A Nag, mT ynnurnere™ a= NNaEssss>> WASHINGTON: GOVERNMENT PRINTING OFFIOR. 1912, BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Maruartr, Entomologist and Acting Chief in Absence of Chief. R. 8. Currron, Executive Assistant. W. F. Taster, Chief Clerk. F. H. Cuirrenven, in charge of truck crop and stored product insect investigations. A. D. Hopxrns, 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, tn charge of deciduous fruit insect investigations. E. F. Puriurrs, in charge of bee culture. D. M. Rogers, in charge of preventing spread of moths, field work. Roiia P. Currin, in charge of editorial work. Maxset CoxcorD, in charge of library. SOUTHERN FIELD Crop Insect INVESTIGATIONS. W. D. Hunter, in charge. F. C. Bisoorp, A. H. Jennrnes, H. P. Woop, W. V. Kine, engaged in tick investi- gations. W. D. Pierce, G. D. Smrrn, J. D. Mrrcneit, Harry Pinxvus, B. R. Coan, R. W. MORELAND, engaged in cotton-boll weevil investigations. A. C. Morean, G. A. Runner, 8. E. Crump, D. C. Parman, engaged in tobacco insect investigations. T. E. Hottoway, E. R. Barser, engaged in sugar cane insect investigations. E. A. McGrecor, W. A. THomas, engaged in red spider and other cotton insect investi- gations. J. L. Wess, engaged in rice insect investigations. R. A. Cootey, D. L. Van Dine, A. F. Conranr, C. C. Krumpuaar, collaborators. 2 LETTER OF TRANSMITTAL. U.S. DEPARTMENT OF AGRICULTURE, BurEAU OF ENTOMOLOGY, Washington, D. C., November 29, 1911. Str: I have the honor to transmit herewith a manuscript entitled “The Life History and Bionomics of Some North American Ticks,” prepared by Messrs. W. A. Hooker, F. C. Bishopp, and H. P. Wood, under the direction of Mr. W. D. Hunter, of this bureau. Ticks are of considerable importance in the United States in two respects. Two species are the sole agents in the transmission of certain impor- tant diseases. One of these diseases is the well-known splenetic fever of cattle and the other the Rocky Mountain spotted fever of human beings. The information contained in this manuscript will be of immediate value in connection with the eradication of the cattle tick and also of the form which transmits spotted fever. The remaining species treated in this manuscript are now of importance principally as parasites of domestic animals. In many localities they present serious problems to the farmer. Moreover, there is a possibility that some of the species not known at present to be carriers of diseases will eventually be found to be of importance in connection with disease transmission. For these reasons full information regarding the life history of the various species is in demand. The work upon which this bulletin is based has extended from 1907 to the present time. The manuscript is intended to be a com- pendium of information regarding ticks which will remain of direct value for many years and make unnecessary the publication of spe- cial bulletins on some of the species treated. I recommend that this manuscript be published as Bulletin No. 106 of the Bureau of Entomology. Respectfully, L. O. Howarp, Entomologist and Chief of Bureau. Hon. JAMES WILSON, Secretary of Agriculture. ma 0 eB et te eal eren oe ae d oe Stee ae ak y “ Pd y | i wy ve Ks te Fi oO Sasi von le bey Pre i can dee bride) arte f Lie J a he fy ay ihe de gal tt] : ne — ath t he a ae | | : iM yE] iT iad wall ih “ene Al y . Ree oo = ee eee ee 199 DLO CYCLO = on Chewine xa sal: vate o> sie tees ale geet ae ie ae eae eee 203 Biconomie Importance ...24 5. acme nia ie heer tale a eee 203 Natural comttole ( > ae ie gee | ee gee ee | a iad a a aloe inset = eins a oe BTN BODO Sh qyuepung y Tanz jouerito (ate |S socersoque org yaj) sale oesqen (alg ya lameci=haa ayo). |jpee ee Biko OR aia SoG) RO ie OCH stysnyjed-stodey sijesAydeuie pT Sg tricr- = STL ae aa a eel a eee es lee SRATIOD Illes a eee ae ee pee ee | ees meee a nies “lee = ook [Pine cone o risa ee plOuO RT SsAaGaleory prrciicre=resioie nig orniaie/e.eig'= >> (do's! 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Oh CT OE Ca SE SEN IC ONE CT a 2 A Te I et aS TENG 1 Sta <1 14158 (Yl (ames cola ae (ae SSO (isl csi ae aes |G ae ne ea oe ees a SO DOX TT MIOL) OO as el bi CR Rid fa eke a a | ear sees Si |inna tans © eal er aeeceinere Talia UtOD Og pets SILO) Site sic alecic/iaicin nae ici gce ciee- isi eid Hd POX BIG.) “uOmImM0, |----sino0a@ | yWepuNgwy |-------=---"|---"- Jone Vi legewem ees Ge eee cles ae ae al ae eee | ae ee ae a age Sas == seer aeitssar SS “7 "snqelUrl sesry lego e siarsl eines Srals'e Sesie/sam = | iseiekeiais siaieis)s ---"gM990 BOSCO BOOSIE SSE eC RSE O01. SE |S RCE Ii EI Pr IO SOS IOC ULI Stel ewe Obs cy aap Sos fer ses |e S Ss os | leteiclege esis alel= nine cio ie / ine SSF i = Pag lee Goo Mee ae ae acceso ane etsieke eta = iam ciofeis)e)-\ateia/aGiais/oiieta ie nisms -**-9]TMISsIp euIMmOATquIy HOUDOUON, |aee cam ae > | SSOUEIOD iis notes Ne hcp [eee tage ee ls gate ale Se Nie aco olga ls Seer geal gg oe oe ones ees sr ~-asuauueleo vUIMMOATG UY *smooQ | Juepunqy |---"77" 777" }-- MOMUMIOD sla see a Se SITIO eft sea ae |S HATIOD Oly EEO Cals aL CULO el: as Ue a ee aa WNnUeOLIOWe BUIMIOAQUIy | | “ured ‘ueI0uog |. | “mUB1ou0g “uUBIU F & -1101]Sny IOMO'T Wi NEALE) reddy ey soy pO BSL *yeo1doly } ‘uvIpeuey) | UeTmOspnyy “OTOLW *‘[eaJsNy JaMo'T ‘Tesny reddy “MOTPISUBL I, ‘sapadg { —= _ — = — Bia “uolsel [eIISny “UOISer [RaIOg "Sy. UDIWAULP YON fO WOLINGLLISIp )DUOZ AY, —"T ATAV PIN OO TID Or OD 23 GEOGRAPHICAL DISTRIBUTION. 3 we he alee, so1opoyymiO SSeS TUTUSIM SOIOPOY}IMIO snaoeL10d SOIOpOy}IUIO Sie See oo ae sT[eijsne snyemnuue sndores1eyy spn ass opaore = sISin = SsTe le se ee Siaiess snyefnuue sndoies1eyy | | aci=\sale\s tele)? soos ees snuexo} Sepoxy, Se KID Oe lcaas eae lne BADOOO) cas tog esl MBCDOOO MIC, mee ol ce og seal Re ee ey Pere Sas Sa nese ae See cae” aa SAMO OS SAD Day 24 LIFE HISTORY OF NORTH AMERICAN TICKS. GENERAL LIFE HISTORY. Although ticks are able to survive long periods of fasting—some species much longer than others—development takes place: only following a period of attachment during which the blood of some animal, either warm or cold blooded, must be taken into the body, i. e., they are obligatory parasites. Several writers have considered the possibility that ticks may subsist in part upon vegetable matter. Prof. Lounsbury, however, who has conducted extensive studies of these arachnids, states (1905) that he has no doubt that they derive nutrition exclusively from living animals despite the protracted periods that they often have to wait for hosts. They do, never- theless, imbibe water from the rain or dew upon herbage or from the soil. One of the writers has observed ticks kept in tubes, on dry sand, to imbibe water from the moistened sand. Many untrained observers have reported that engorged ticks give birth to living young. Ricketts (1909a, p. 104) mentions this phenomenon as having been described to him concerning Dermacentor venustus by a number of residents of the Bitter Root Valley, Montana. While the origin of such erroneous statements can not be determined, one explanation to be offered is that of mistaking some of the Kermes for ticks. Thus Kermes galli- formis has been sent to one of the authors by an entomological collector who supposed it to be a tick. With the Kermes was a statement to the effect that it had been found dead with young swarming from it. DEVELOPMENT. All ticks pass through four distinct life stages: (1) The egg, (2) the larva or seed tick (6-legged stage), (3) the nymph or yearling tick (first 8-legged stage), and (4) the adult. Ali the ixodid and one (or more) of the argasid ticks engorge and molt but twice before arriving at the adult stage. Two species of Ornithodoros are re- ported to remain inactive in the larval stage and pass the first molt before engorging blood. Some of the argasids molt twice or three times during the nymphal stage, and at least one species continues molting after becoming adult. The larve of Ornithodoros talaje, which species is now being studied, engorge, then drop and molt twice before the next engorgement. The ixodid ticks engorge but once as adults, and die following the completion of oviposition, while most of the argasid ticks engorge a number of times as adults, oviposition following each engorgement. MOLTING. There is wide variation in the molting habits of ticks, even among species of the same genus. Most of the ticks, both argasid and * ixodid, molt while away from the host, and the habit of molting HOST RELATIONSHIP. 95 while attached appears to be a special adaptation. One native species (Ornithodoros megnint Dugés) and several exotic species (Rhipicephalus evertsi, R. bursa, Hyalomma xgyptium) pass the first molt upon the host, but drop for the second. , Nov. 4,07 | Rabbit__-. 1) 0} OF 0} OF 0} 0/0/0)/0)/0)18)0)/0)0) 0) 0) 0)0) 0)0 Nov: 5,070} ....d0---. ..2 l O} O-f:04) 0.) 0.) 0190) 0 | OT SOs), 0 | 0,0 15 0 | OO OOo Apr.10,08 | Bovine... . 3 0/ 0/0] 0/0} O19!12g}0/0)/0)0)0;0) 0; 0;] 0,;0)0)0 Apr tt.0on|2- 500s =e sc 6] 0} 0/0) 0 ]19} 0 1d/19]119;}0);0);0)/0/0; 0] 0; 0;/0);0);0 “4d | Apr.12,08 |...do...... 2} 0] 0/0] ojo {igo }o}o ofojo/o/o] 0} 0} ojojojo | June 6,08 |...do...... 5| 0 restr \og/0] 0} 0/0]/0|0/0]/0)0;0/ 0} 0} ojojojo June 7,08 |...do...... 24 | o PS iesiosto| o|o/o/0/o)0]/o0/o0/0) o| oJ ojojojo ¢ | June 8,08 |...do...... re (sesree 13}0} 0/0/0/0/0}0)0/0}0} o| o| ojofojo Q|2 June 9,08 |...do..-... SONOS LON ONtOR POM OF Os On FON MON TOM) On Onl Or ianerire Nov.10,08 | Quail....- DF 20) | OL 80s) OC On ORONO ON FOR ON LOMO) Onl) (OF) SON Os OR One ayaa Rabbit_... DF he OV! PONRO! O20: 1 FO) 02) OF) 0" F090) FO FOE FON Ona 0) 0/2) 2 Jee. 29,09 | Chaparral 1g)\\, | : ee 6] 0| 00] o/0| ojojojo 0} 0) 0/0 0 isHis {ag 0|0 Mo tales. -Seee ee Ua Ss. | Mecteck| Sime |eeala elec aies-| Meets SFA ee eae | ORE ee peeess|. Sherali 1 a SS a ee . wes Jegade nell leg a lee Engorged nymphs 2 molted—days fol- Number molted. pan. rei ra ae Date lowing dropping. ; eLUEIErc engorged : Num-|_ = —_— nymphs Host. ber. | | } dropped. ; Mais Mini. | Average 100 | 104 | 112 | 113/124) ¢ Q Total. nian shine warty °F. OR: °F. Nov. 4,07 | Rabbit.... Dip Ol | (Os 20s) Os iO il 0 MT Eee Os Heo Keene ae acoso Wows 5:07 jen.G0. 3.56. Leen On| COM eeON| 0 1 Oe eS ee ee eee mec = Apr.10,08 | Bovine.... Or OF OF 0") “OR 0 2 1 3 83.0 47.0 68.84 ATA L 0832-100 o~ 2-5-5 Ga eT OF Oc Or ity 1 3 t+ 83.0 47.0 68.98 Apr. 12,08 }..-do..-...- 22110] O72 On). 0) ea0 1 1 2 83.0 47.0 70.07 June: 6;08").4do. . 22-3 Bil 0} 20") Os] 2018.0 4 1 5 91.5 69.0 80. 52 June. 7;081)=- do... =. => 2441) 100) SO BOs CaO 8 15 23 91.5 69.0 80.57 June 8,08 |...do.. Ds) (ON MON SON) One @ 5 7 12 91.5 69.0 80.39 June 9,08 |...do......- 20 FOF) “Ohin OG 1D eee 2 91.5 69.0 80.55 Nov.10,08 | Quail...... 210) Out Obs Oa0 0 2 2 82.0 34.0 59.15 Nov.25,09 | Rabbit.... ry Ge eae te me ay mee a | a et el ec oc « a4 83.0 17.0 58.34 Dec. 29,09 | Chaparral 6 tOF| One OO) 4G 3 2 5 87.0 17.0 61.62 cock. . Motalltsse<. cece oe UA co) occ bac oc ace 26 33 Ban 6 ewes ce|teck s. Soe eee ¢= Male. O=Female, THE RABBIT TICK. 95 The adult (Table XX VITI).—The longevity of adults of this species is probably equal to that of any other ixodid tick. In a tube which contained a lot of about 24 adults which molted from nymphs shortly before September 29, 1909, the last individual, a female, died May 10, 1911, having lived at least 588 days. A male in another lot which molted to adults between February 22 and March 29, 1910, lived for 403 days. In a third test a female in a lot which molted between March 23 and April 4, 1910, died on May 10, 1911, after a period of 401 days. One male ina lot of about 6 males and females which became adult April 15, 1908, lived for 395 days. The longevity of several other lots of ticks upon which the date of molting was recorded ranged between 109 and 355 days. These lots became adult in the spring and early summer months. A longevity of from 17 to 167 days was observed in the case of 10 lots of adults collected on hosts during 1909 and 1910. Considerable difficulty has been met with in getting females to engorge. Although males and females have attached in conspicuous places on the ears of tame rabbits, we have failed to observe them in copulation. A small female dropped in 17 days, but the only female which attained full size required three weeks for engorgement. The last individual, the engorgement of which is recorded in the following table, was placed on the host without males. Mr. George Wolcott, who observed this engorgement, found that it attached in less than half an hour. It remained for at least three weeks before any appreciable engorgement took place. In the last three days engorgement was very rapid. TaBLe XXVIII.—Engorgement of females of Hemaphysalis leporis-palustris. Female | Period Adults applied. | Host. dropped jof attach- Size engorged. engorged.) ment. Days. Ta ONS See ory tao cis onc ay aimn cstetomise nt Rabbit....| July 25 17 | 6 by 3.5 by 2.5 mm. DON et ess Pech) cea ha eee T ACs (operas Ee July 29 21 | 10 by 6 by 3mm. 1D 0) 36 Ne ee IEE SS ets ie i ES Eee GOs cee Aes co 26 | Scratched off. Pars was VORUSS tok... ee - Be et en eae Ae Bee 0 koa ae Feb. 18 35 | Fully engorged. LIFE CYCLE, This tick may commence to oviposit as soon as the fourth day after leaving the host. The largest number of eggs deposited by an individual was 2,240. The eggs have been found to hatch in 22 days. A total effective temperature of at least 902° F’. is required for incuba- tion. Larve have been found to live 258 days. _ They may engorge and drop in 5 days after attaching to a host. Molting of larve may begin in 18 days. A total effective temperature of 463° F. appears to be required for the transformation to nymphs. Nymphs may live 96 LIFE HISTORY OF NORTH AMERICAN TICKS, for 342 days. They may engorge in 4 days after attachment and begin molting 13 days after dropping. A total effective temperature of about 486° F. is required to produce this transformation. Adults may live for 588 days without food. Both sexes have been found together in abundance on wild hosts, but copulation has not been observed in ticks reared experimentally. Females may drop engorged in 17 days after attachment to a host. The three stages of the rabbit tick have been taken from hosts in nature during all seasons of the year. We have found the immature ticks in great numbers on ground-inhabiting species of birds in the fall and winter; they may, however, be equally numerous in the summer. ECONOMIC IMPORTANCE. On account of the fact that this tick confines its attack to rabbits and wild birds, it is of no importance economically. In a few instances the species has been known to become so abundant on wild rabbits as to render them so weak that they could be easily killed by their enemies. Mr. W. V. King killed two snowshoe rabbits (Lepus bairdi) at Florence, Mont., on April 3, 1910, which were infested with 1,033 ticks. Many of these were fully engorged females. The large number of specimens found on quail and meadowlarks leads us to believe that in some cases the young of these hosts may be killed by tick attack. NATURAL CONTROL. The bird hosts of the rabbit tick undoubtedly destroy a considerable number of them, although they also serve as disseminators of the species. As has been stated, rabbits have been observed by us to devour engorged ticks and no doubt some specimens are injured by the scratching of this host. The smaller birds, such as sparrows, and certain reptiles and batrachians, are also probably of some importance in the destruction of this tick. It is known that this species 1s parasitized in the nymphal stage by a chalcidid. This parasite (Ivodiphagus texanus), the first recorded as having been reared from a tick, was described by Dr. L. O. Howard (1908) from individuals reared at the tick laboratory from engorged nymphs collected by Mr. J. D. Mitchell in Jackson County, Tex. A single specimen in each of two different lots of engorged nymphs was found to be parasitized by this insect. One of these lots was collected March 10, 1907, on a cottontail rabbit and the other May 1, 1907, ona jack rabbit. Subsequent collections in that locality have failed to reveal other parasitized specimens. Bul. 106, Bureau of Entomology, U.S Dept. of Agriculture. PLATE VII. THE RABBIT TICK, H4MAPHYSALIS LEPORIS-PALUSTRIS, AND THE BIRD TICK, HAMAPHYSALIS CHORDEILIS. Hemaphysalis leporis-palustris: Fig. 1—Unengorged larva. Fig. 2—Unengorged nymph. Fig. 3.—Engorged nymph. Fig. 4.—Engorged female. Fig. 5.—Partially engorged female (balsam mount). Fig. 6.—Male (balsam mount). H«maphysalis chordeilis: Fig. 7—Male, dorsal view. Fig. 8.—Male, ventral view. Fig. 9.—Engorged nymph, dorsal view. Fig. 10.—Engorged nymph, ventral view. (Original.) LIFE HISTORY OF NORTH AMERICAN TICKS, 97 THE BIRD TICK. Hemaphysalis chordeilis Packard. The common name of this species is applied on account of the fact that birds are its principal hosts. DESCRIPTIVE. Adult (Pl. VII, figs. 7, 8)—Males from 2.8 by 1.5 mm. to 2.9 by 16mm. Scutum light gray in color, shading into amber anteriorly; marginal strip bluish white; legs and capitulum amber. Females, unengorged, from 2.8 by 1.4 mm. to 2.9 by 1.8 mm.; engorged, about 9 by 6.6 by 4 mm.; reddish brown in color when unengorged, scutum without markings. Nymph (PI. VII, figs. 9, 10).—Unengorged, 1 by 0.65 to 1.4 by 0.72 mm.; light brown in color, scutum darker; engorged, about 2.43 by 1.79 mm.; color dark gray. Capitulum 0.217 mm. in length (from tip of palpi to base of emargination of scutum); scutum 0.446 mm. long by 0.447 mm. wide. Larva.—Unengorged, from 0.552 by 0.402 to 0.574 by 0.430 mm.; body ovoid, yellowish brown; engorged, from 1.4 by 0.8 by 0.6 mm. to 1.5 by 1 by 0.6 mm.; abdomen slate color. In most cases three distinct longitudinal white lines are to be seen on the dorsum; shield very dark brown, almost black posteriorly, shading to a pale yellow-brown anteriorly. The legs and mouthparts are translucent yellowish brown. Capitulum 0.125 mm. in length (from tip of palpi to base of emargination of scutum), scutum 0.240 mm. long by 0.308 mm. wide. Egg.—No eggs of this species have been seen by us. HOST RELATIONSHIP. The type host of this species is the nighthawk. The species has a comparatively wide range of bird hosts. Those species which are more or less ground-inhabiting seem to be more frequently infested. The immature stages of this tick are frequently found in large num- bers, usually attached to the heads of the hosts. They are very fre- quently associated on the hosts with the immature stages of Hema- physalis leporis-palustris. The following birds have been found to act as hosts: meadowlark, jackdaw, red-winged blackbird, marsh hawk, quail, and domestic turkey. Mr. Banks mentions having seen a nymph, probably of this species, from the killdeer. The examina- tions of birds in Texas indicate that the meadowlark is by far the most commonly infested host. We also have a fairly reliable record of three adults of this species having been taken from a prairie chicken in Texas. As has been stated, the ticks are usually found to attach on the top of the head. They are also found around the eyes and ears and occasionally under the bill. 21448°—Bull. 106—12——7 98 LIFE HISTORY OF NORTH AMERICAN TICKS. GEOGRAPHICAL DISTRIBUTION. The type locality for this species is Milton, Mass. Specimens have also been taken at Norwich and Taftsville, Vt. Most of the other collections were made in Victoria and Refugio Counties in Texas by Mr. J. D. Mitchell. We have one authentic record from D’ Hanis, Medina County, Tex., and one of the authors (Hooker) collected larve and nymphs which he thought were this species at Grand Cane, La., and Hawthorn and Quincy, Fla. It is very probable that this tick has a wide range of distribution, but owing to the fact that little collecting has been done upon birds in other localities, the range of the species is not fully known. LIFE HISTORY. Little has been published on the biology of this tick. Hooker (1909a) reports the finding of molted larval skins attached to the head of a meadowlark. These were associated with engorged larve of this genus and it was thought that they might be exuvia of the bird tick. The egg.—Owing to the difficulty in securing engorged females no records have been made upon preoviposition and oviposition periods. The number of eggs deposited by this species has not been determined. Dr. Philip B. Hadley, of the Rhode Island Agricultural Experiment Station, kindly sent Mr. Nathan Banks a large number of larve which hatched about August 15 from eggs deposited by a number of engorged females collected on turkeys at Norwich, Vt., June 28, 1909. These larve were forwarded to us at Dallas, Tex., by Mr. Banks. The larva (Tables XXTX—XXX).—The longevity of the larva of this species has not been definitely determined. Larve of one lot which hatched about August 15 lived at least 39 days. At the end of that period they were placed on hosts. As is indicated in Table X XIX, larve have been engorged on rab- bits and guinea pigs. Two attempts to engorge them on chickens failed, though a few were found to attach. Attachment was found to take place very soon after the larve were applied, usually within 5 to 30 minutes. Dropping began as soon as the fifth day after attachment. The longest period of engorgement observed was 12 days. The weighted average time from application to dropping in the case of the 33 larve engorged was 7.5 days. THE BIRD TICK. 99 TABLE XXIX.—Engorgement of larve of Hemaphysalis chordeilis. Larvee dropped engorged—days Date N following application. Total larvee Host. har? number | State of engorgement. applied. dropped. 5 | 6 7 She 9 4 LOM tela ene | 1909. Sept. 7| Rabbit........ 51] Maul) al] ol Bi) eh] oul ao 21 | Fully. Beptsmet | Hels. ..c-os55- i Ol Ol GIO Ol Owl w 0 Sept. 17 | Guinea pig. . 75 Se Sree td eer be clan mae ot 2) Fully. Sept. 18 | Hen=...:-:=-% Dee Ol Oi Ol | On OF Os EONS 0 Sept. 22 | Rabbit........ A AD) OM ON ee tt hy ihe) eo 3 | Two-thirds to fully. Sept. 24 |..... Obert one. TEE (OM OO OI esa) ery ale ayy a 7 | Two-thirds to fully. Total... P72 1iy NSS ie Seer Meee) eee ere ere eee 33 At a mean temperature of 79.05° F. molting began on the four- teenth day after dropping. When the mean temperature fell to 53.98° F. 76 days elapsed before molting began. This and the other long molting period given in the table were recorded on larve col- lected from wild hosts, and although the state of engorgement of the ticks was not recorded, there is little doubt that they were not fully engorged. This would tend to lengthen the molting period as has been ‘found true in all observations made by us on this point. A total effective temperature of 505° F. appears to be required for this transformation. TaBLE XXX.— Molting of engorged larvxe of Hemaphysalis chordeilis. Temperature from Engorged larve molted—Days following dropping. dropping to date first tick molted. Date Num- pumazeed Host. nee fn | alae | i | i dropped. GINTESO ||" || Total ol Parse ver- 14|15|16| 17] 18 | 19|21| 26|32|42| 67/76 eoee Meee | Mi ae | eae 5 y Bias! | : 1909 | | 9 cet Naas SIN i Sept. 12] Rabbit.| 6 He: |b Tipe 0 Seal Saelkee saa-c| 3 | 98.50 | 59 79.84 Sepia ndomee | Ob gl IN eee) ee 11 Goose aii leea a Eee S| 6 | 96.50 | 59 79.05 Sept. 14 4do28 2 UO eal Sale wel te ales rere ee 1 | 95.50 | 56 77. 28 Sept. 17 -(i y= 2 oi 1 Be | ae ae 2 | 95.50 | 56 6.75 Sept. 25 -do.. | avo) ecnilosolseclbes Bee ey |) | =e | 1} 92.50 | 51 72. 38 Sept. 30 |...do.. ba | Celt 2 hal hell ie 1 | 92.50 | 51 72.77 Oct 2 -do.. 2 | 1 |e at! nae 2 | 92.50 | 52.50 73. 80 Oct. 3 Soles 0) A Boal Seeleeel msl eeetiaes else ae 1 | 92.50 | 52 72.88 NG yiPRL64| Loh! reeset Mest | asst a < ae a 2 2) Sept. 22, 1907.....| Dog..... rly sae pete, RS (SN. Piet 3 ae aes 1) 1) 20 oe ee Oct. 27, 1907... Shae Pee yates ily Bee e Soa pel ee Mar aaa baal ieee Dsl) | S| be oe eee Nov. 11, 1907....- Bovine Di LO) Baleee ses] see seaciles = 1 Lally (2:98 nen eet eee INOv.42)19072---4|-22 dor. Gi VO a ONO} Cee rere seers ue AL |" 16 ile 2 5c A eta eee|| Seroeeee Apr. 22, 19081....; Dog....- LL ger eee Bee PSS bee eso heel Pere eee eB eee 11] 86.0] 47.0} 70.39 July 17, 1908....-- Bovine.. Byles |Seee Per Per oat solMeolsen 2 1] 3] 95.0] 76.5] 84.65 July 18, 1908......|.--do....- 10) (5 ee eS Bes Eee ee see) Pel Ree era) 4/10] 95.0] 76.5 | 84.70 uby219; 19082... | -.00.=. 2 WOR aaa) eee Bel ea et eae sel echo 6 8| 14] 95.0] 76.5] 84.69 Tuly 20, 1908. ..2:.|...d0..2.2 Fil epee ae Se ial eae iC llea eS 1) 4] 95.0] 76.5] 84.92 Duly 21; 1908s bee doles Ch) eo Be este | eat) eel reer See ee 0 2| 2) 95.0). 77.0°| 85.42 Aug. 17, 1908 2....]| Dog...-- LOOM Soca beea|mct |e aralceel eee setal sealed 40 | 67 | 96.0} 75.5] 83.90 Awe. 18, 19083. .-_ |: do...... LOOM Ee | 22 | ee ge (eed ere) beter |) 33 | 53] 93.0) 75.5] 83.55 Nov. 29, 1909.....|.-- GOs--<5 CYS ee pene (ora Meme 75 0) UR Se | Fake ae Sr 17 | 92.0} 20.0:| 55.97 Total BPA eel lee 67 96°19} |... 222 -|asbeses| see 1 Collected at Brownsville, Tex. 2 Collected at Brownsville, Tex.; 27 of these nymphs were parasitized. 3 Collected at Corpus Christi, Tex.; 40 of these nymphs were parasitized. The adult (Table XXX VI).—Of 163 adults which were observed to molt from nymphs, 96, or 58.9 per cent, were females. The greatest adult longevity observed by us was between 204 and 214 days. This record was made on alot of 13 males and 15 females which molted from nymphs September 1, 1908, and were kept in a tube on moist sand in the laboratory. On March 24, 1909, or after 204 days, a male and a female were alive. These were both dead on April 3, 1909. Other specimens which became adult in early September were found to live nearly as long as the lot above referred to. Several lots of ticks THE BROWN DOG TICK. 109 which became adult late in July and early in August lived from 77 to 158 days. One lot of ticks which became mature on May 18 to 21, 1908, lived about 3 months. Of a lot of 91 individuals collected on hosts on July 21, 1909, 4 were still alive December 15, 1909, having lived at least 147 days. However, a large percentage of the adults collected from dogs in the summer die within a month or 6 weeks. The longevity of the sexes appears to be about the same. We have observed unengorged adults crawling from between the cracks in floors. At Corpus Christi, Tex., they were found in considerable num- bers in the cracks of a porch floor where dogs frequently slept. Christophers reports that after molting adults crawl into straw or sim- ilar material and there await the host. Mating, which takes place on the host, may commence as soon as the fourth day after attachment and often continues until the en- gorged female drops. The male sometimes drops with the female or detaches soon after and goes in search of another mate. In one instance a male and partially engorged female in a tube on sand were observed apparently in copulation. On November 19, 1909, Mr. J. D. Mitchell collected a male Am- blyomma americanum in coitu with a female of this species on a dog at Corpus Christi, Tex. The mouth parts of the male were again inserted in the genital opening of the female when the ticks were put in a vial and they remained in this relation for at least fifteen minutes, when they were packed for mailing. Subsequently the female, which was partially engorged, deposited fertile eggs. Fertilized females were found to engorge more rapidly than unfer- tilized ones. In one instance a female engorged in 6 days, while in several instances females remained attached for from 44 to 50 days, and even then were not fully engorged when they dropped. It is quite apparent that fertilization is an important factor in the period required for engorgement, as in the short period mentioned above the ticks mated on the fourth day after attachment, while in the ex- tremely long periods mentioned mating did not occur at all. TaBLE XXXVI.—Engorgement of females of Rhipjcephalus sanguineus. Females Period Adults applied. Host. dropped en- ee ae Size engorged. gorged. ment. Days. OCTRAG NO0Tcsc8 jo 6.522 85-5 ee eect eke ae Dor. 24242 Nov. 2,1907 7 | 9.5 by 6.5 by 4 mm. WD) Omens eters ce ee hist aise ne eer enone Nov. 3,1907 8} ll by 7 by 4mm. DH SAMIOOR re 3s ek oye cia: Se eee ee Bovine. Feb. 17,1908 44 DRE E SABE eer aa a ieee teins Ue SAC EES: Feb. 18,1908 45 | 8 by 5 by 3 mm. DO Saree ae se cg Ra twad sn. 2eSs2 88 See Ole Feb. 23,1908 50 PIES eI ce meet fe etic ae eecionicenicad + 3s 2 adOes aon = Apr. 10,1908 6|9by 6 by 3 mm. LDXOSE EEE SE One ocr, See ene nea eee sel ae dox:. 35. Apr. 11,1908 7| 8 by 5 by 2mm. Oe 5s eee ee Pr fo 8 2 ea (0 Loe ae Apr. 12,1908 8 | 6 by 4 by 1.5mm. DORIS ES ree ORs se oek teceeeeue Sag -Ec doss.. 2eedOrteses st 8 | 8 by 5 by 2mm. ————————————————e——ee eee ee . 110 LIFE HISTORY OF NORTH AMERICAN TICKS. Males do not appear to remain attached to the host after the females have dropped. If they do not drop with the females they start out in search of another mate; in this search they frequently go from one dog to another. Their longevity on the host is at least several months. LIFE CYCLE. Oviposition may commence as soon as the third day, and as many as 2,616 eggs may be deposited. In August eggs may hatch in 19 days, an accumulated effective temperature of 774° F. appearing to be required for their incubation. Larve may live for 131 to 138 days while waiting for a host; they may engorge in 3 days and molt in 6 days. ) June'8-..-- 25 | Aug. 24 116 77 The nymph (Tables XLIJII-XLIV).—The nymphs were found to molt as soon as the eighth day, or 14 days after attachment, the last observed molting on the thirteenth day, or 19 days after attach- ment. It was observed that in molting, as in annulatus proper, the young nymphs detach from the old point of attachment and reattach about one-eighth of an inch away, the old skins remaining attached to the hide after being shed. Pound reports 7 days to be required for the nymphal stage, while Lahille places this period at 9 days. The adult (Tables XLIJJ-XLIV).—In molting the females, like the nymphs, move from the old points of attachment, leaving the skins, and attach from one-sixteenth to one-eighth of an inch away. The mating habits of australis are similar to those of annulatus proper. After molting the male feeds for a number of hours and then starts in search of a mate with which, when found, it may remain until the female drops engorged. Males have been observed to remain in the position of copulation with females of Margaropus annulatus and Dermacentor nitens as long as 3 days. Lahille has observed copulation to take place off the host. We have not deter- mined the period that the males remain upon the host, but Lounsbury states that it is usually about a month. The adults have engorged and dropped as soon as the twenty- second day after attachment or 8 days after molting. In three infestations observed, the last engorged female dropped on the twenty-seventh day from attachment, or 9 days after the last nymph was observed to molt. Lounsbury reports the parasitic period (from the application of larve to the dropping of the females) to be from 18 to 38 days, but usually 23 days. THE AUSTRALIAN CATTLE TICK. 1981 TaBLE XLIII.—The parasitic period of Margaropus annulatus australis. INFESTATION No. 1. Date. Remarks. 1908. Apr 1G; AyD) dees. gene cweae ssc Larve placed on bovine. Apr. 7 (1st day)........--.....-| All attached. Apr 2) (Hthiday re. 24. 5.--5-2% Several larve molting. Aprsta (iil Gay) seses. 2.552 5.- A large percentage molted. pr 4 (Sth day) o.. 22)... 78 All larvee molted. Apr. ai (bth Gay)==-----.--2-- Four nymphs molted (3 males, 1 female). Apr. 22 cae (6 Eh) eee peeienne eiae A total of 20 molted. Apr 2s (Let ay))o =. s-cossae A total of 40 molted; one not molted. Apr.24 (18thiday)). 15-5. 2.- All have molted. Apree0 | (L9tH Gay) =< 1c =get- ces = Several mated. Apr. 27 (21st day)-...........-.-] One female fully engorged but still attached. Apregs(Q2diday)'s22 ss sae tee One female dropped engorged. - PATE 20 (200 SY) aoSernccc oon Two females dropped. Seven fully engorged still attached. re 30 (24th day) Fourteen females dropped engorged. ay 1 (25th day)...--...--- --| Four females dropped engorged. Meyr3di(27thiday))|s ciiccir- 2 544 The last female dropped engorged. INFESTATION No. 2. PATIOS TT aaNet se ceiews etnies Larve (hatched July 11) placed on bovine. Apu IZiGStiday ia. fabseaec 2 All attached. Ade (bn day ees. oes ccoce Several molting. ANTE SICA ay 45 3.. 05252586 All but two or three have molted. Aug. 19 (8th day).......... -| All have molted. Aug. 25 (14th day) .-| Twonymphs molted to males. Aug. 26 (15th day) Three more have molted. Aug. 28 (17th day) All have molted. Aug. 29 (18th day) All mated. pepe. List day). i2si23255.2.2 Several females fully engorged Sept. 2 (22d day) ..-.-----.---- Six females dropped engorged. Aug. 4 (24th day)....--.-.----- Five females, the last, dropped engorged. INFESTATION No. 3. ATION2O SO DMs .c0 Sete ce -Scles Larvee (hatched July 11) placed on bovine. ATTEN QU GIStday io. a o-)h 422 All attached. Ae. 26) (6th Gay). <2 c a... ee Several molted. Ae .129 (Sth day) 2>.. <5: --252- All have molted. Sept. 5 (16th day)..............| Several nymphs molting. Sept. 8 (19th day)..............] All the nymphs have molted. Sept. 12 (23d day).........-.--.] Four females fully engorged. Sept. 13 (24th day)..........-..| Four females dropped engorged and several others are fully engorged. Sept. 14 (25th day)-............-| Eighteen fully engorged females were removed. Sept. 17 (28th day)..........-.-| One fully engorged female removed. Sept. 18 (29th day)..........-.-| One fully engorged female, the last, removed. Taste XLIV.—Summary of parasitic periods of Margaropus annulatus australis. Larve. Nymphs. Tne First molted. Last molted. First molted. Last molted. as —— Period a . - follow- tion. Period Period : 3 os follow- follow- Para- Para- ee Date. | ingat- | Date. | ingat- | Date. | sitic Pe Date. | sitie pe- amenih tach- tach- riod. riod. < ment. ment ee er ee eee eee eS 1908. 1908. Days. 1908. Days. 1908. Days. 1908. Days. | Days. eae Apr. 6] Apr. 12 6 | Apr. 14 8 | Apr. 21 9 | Apr. 24 12 15-18 23 S554 Aug. 11 | Aug. 17 6 | Aug. 19 8 | Aug. 25 8 | Aug. 28 11 14-17 Be cieac Aug. 20 | Aug. 26 6 | Aug. 29 9} Sept. 5 10 | Sept. 8 13 16-19 122 LIFE HISTORY OF NORTH AMERICAN TICKS. Taste XLIV.—Summary of parasitic periods of Margaropus annulatus australis— Continued. Females dropped. Infestation. Hirst, ca Period —_—_— perce aie sua attach- Datel Parasitic Date. Parasitic ment. period, period. 1908. Days. 1908. Days. 4 Days. 1 RRS ee te kno eis Silas aida tis Sarasa es Se Oe eee Apr. 28 7| May 3 22-27 oT te he ey eS Se ON ae a Ie eS een elgie o he ieee Sept. 2 8 | Sept. 4 10 22-24 Re areas e ae cots einiein yr area mala create Sian ea eta ioeinians hs Sept. 13 8 | Sept. 18 13 24-29 LIFE CYCLE. Under favorable conditions the progeny of a single tick may survive for a period of 82 days from the date hatching commences. The larve usually molt on the sixth day following attachment to the host, although in some instances as many as 9 days may be required. The nymphs usually molt in from 8 to 10 days later, but as many as 13 days have been observed to be required in some instances. Adults have been found to engorge in 7 days. In our observations the last females dropped engorged on the twenty-ninth day from attachment, but the period would probably be longer if males were not present. In one instance oviposition commenced on the day following dropping, but usually several days pass before such takes place. In June, at a mean temperature of 78° F., hatching began on the twenty-third day. An effective temperature of 834° F. appears to be required for incubation. ECONOMIC IMPORTANCE. This tick is so closely related to our species (Margaropus annulatus) that what has been said of annulatus proper regarding its impor- tance as a pest may also apply to it. In the countries where it occurs australis is the same great pest that annulatus is in the southern United States, and transmits Piroplasma bigeminum in a similar manner. The habit of the larve in attaching to man, how- ever, adds to its importance. ' NATURAL CONTROL. As with annulatus, birds (particularly blackbirds), mice, ants, toads, and lizards are probably its principal natural enemies. In Jamaica, the tinkling grackle (Quiscalus crassirostris), and the ani or “»arrot-billed blackbird” (Crotophaga ant) are reported by Newstead (1909) to be its principal bird enemies. THE GOPHER-TORTOISE TICK. 123 ARTIFICIAL CONTROL. The methods applicable in the control of annulatus proper apply in a general way to australis. Our observations indicate that the longevity of the larvee may be somewhat shorter than that of annu- latus. ‘The long periods of warm weather in the Tropics should greatly assist in its eradication through starvation. If, however, the larve attach to small animals, as has been reported by Newstead (1909), and these develop to adults in any numbers, its eradication will be much more difficult. Genus AMBLYOMMA Koch. The five species of the genus Amblyomma which occur in the United States, namely, americanum, cajennense, dissvmile, maculatum, and tuberculatum, have been studied and are considered in the following pages. The other species of this genus whose biology has been studied are variegatum by Barber (1894-95), in Antigua, goldii and varium by Rohr (1909), in Brazil, and hebreeum (1899), marmoreum, and variegatum (1905), by Lounsbury, in South Africa. All five species which occur in this country and the three species studied in South Africa drop to pass the two molts. This also appears to be the case with the Brazilian species studied. Aside from the species which as adults attach to cold-blooded hosts only (dissimile, goldii, marmoreum, tuberculatum), the host relationship is not closely restricted. The species are able to withstand long periods of fasting while waiting for a host. While americanum is widely distributed, occurring in the Boreal and Austral regions, the other four species have only been found in the Tropical and Lower Austral Zones, three of these occurring only in the Gulf strip of the Austral Zone. The species are very hardy, yet require some protection, such as timber or underbrush; maculatum, however, exists on the prairie. Only one species is known to transmit disease, namely, hebreeum, which conveys the infection of heartwater of sheep, goats, and cattle in South Africa. Experiments to determine the possibility of americanum acting as a transmitter of splenetic fever of cattle have been conducted by two investigators. In both cases the results were negative. THE GOPHER-TORTOISE TICK. Amblyomma tuberculatum Marx. The common name of the species is taken from the host of the adult. DESCRIPTIVE. Adult (P|. IX, figs. 4-8).—Males from 7 by 4.5 mm. to 8 by 5 mm. Females, unengorged, 7 by 5 mm. to 10 by 6 mm.; engorged, 19 by 13.5 by 8 mm. to 24 by 18.5 by 11 mm. Males, scutum reddish 124 LIFE HISTORY OF NORTH AMERICAN TICKS. brown, with a somewhat complicated pattern, formed by rather broad metallic bands. Female reddish brown, scutum with a large silvery mark on each side, containing one or two dark spots, and two divaricate, silvery stripes extending forward from the hind margin and sometimes connected with the lateral spots. Nymph (P1. IX, figs. 2, 3)—Unengorged, 2.25 by 1.5 mm. to 4 by 2.5mm.; engorged, 7 by 5 by 2.5 mm. to 10 by 6.5 by 4 mm.; capit- ulum 0.932 mm. long (from tip of palpi to base of emargination of scutum); scutum 1.2 mm. long by 1.6 mm. wide. Unengorged nymphs are reddish brown; the scutum has a large silvery spot on each side, united behind at the tips and in front much -broken by the large punctures. Engorged nymphs are dark gray in color. Larva (Pl. TX, fig. 1)—Unengorged, about 1.03 by 0.76 mm.; engorged, about 4 by 3 by 1.5 mm. The color unengorged is brown- ish yellow, intestines showing through darker; lateral margins of the scutum of a pinkish color. The color of the engorged larvee varies considerably; partially engorged specimens are usually dull gray and those which are fully engorged or nearly so usually have a purple color. Larve that have been fully engorged for some time have a bluish brown color. Egg.—Ellipsoidal, reddish brown, shining, smooth. Maximum for 10 eggs measured 0.893 by 0.647 mm.; minimum 0.847 by 0.647 mm.; average 0.864 by 0.655 mm. HOST RELATIONSHIP. The adults of this tick have been collected from the gopher tortoise only. Experimental attempts to attach them to bovines have failed. The nymphs are commonly found on the gopher tortoise and have been engorged in experiments upon a bovine. Engorged larvee have been collected in large numbers from dogs and rabbits and in smaller numbers from cattle and two birds of prey, namely, the owl and the hawk. The fact that the bird hosts discovered have been birds of prey has suggested the thought that the larve crawled to the bird host from the small mammals devoured by them. GEOGPAPHICAL DISTRIBUTION. (Fig. 8.) The type locality of this tick is Crescent City, Fla. ‘The species appears to be commonly met with on the peninsula of Florida as far north as Hawthorn and it is reported as being rather common in southern Alabama. Neumann (1899) reports that there is a male in the Paris Museum which was collected in Cuba. Bul. 106, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE |X. THE GOPHER-TORTOISE TICK, AMBLYOMMA TUBERCULATUM. Fig. 1.—Unengorged larva. Fig. 2—Unengorged nymph. Fig. 3.—Engorged nymph. Fig. 4.— Engorged female, dorsal view. Fig. 5.—Females engorging on tortoise’s feet. Fig. 6.—Male, dorsal view. Fig. 7—Unengorged female, dorsal view. Fig. 8—Engorged female, ventral view. (Orig- inal.) THE GOPHER-TORTOISE TICK. 125 LIFE HISTORY. Observations on the biology of this tick have been published by Hooker (1909a). The egg (Table XLV).— Three females were engorged upon a box tortoise. Their respective dimensions were: 24 by 18.5 by 11 Fic. 8.—The gopher-tortoise tick, Amblyomma tuberculatum: Distribution. The large dots show localities where the species has been collected in our investigation. The small dots indicate the probable range of the tick. (Original.) mm.; 19 by 13.5 by 10 mm. and 19 by 13.5 by 8 mm. The first female weighed 2.35 grams. This and the last female had a pre- oviposition period of 8 days at a mean temperature of 84° F. The second female began depositing on the tenth day after dropping. 126 LIFE HISTORY OF NORTH AMERICAN TICKS. The deposition period of the first and second females was 21 and 16 days respectively. The largest number of eggs deposited was 5,481; the average 3,839. Oviposition continued in one case for 21 days. Many of the eggs deposited by these females were black and shriv- eled when deposited and ultimately only a very small percentage of them hatched. It is believed that in nature several thousand more eggs would be deposited, as the females observed by us were still of large size when deposition ceased. The first female recorded in the table died on the thirty-fourth day after dropping and the second female died on the twenty-eighth day. Although the engorged females are much larger than in Amblyomma maculatum, the number of eggs deposited is probably less, due to the much larger size of the eggs of tuberculatum. The process of oviposition is very similar to that of the South African species of Amblyomma as described and illustrated by Lewis (1892). The viscid membranes or papille are protruded from between the capitulum and the scutum to a far greater extent than in Margaropus annulatus, as observed by Cush- man (see p. 73). This membrane is Spelenece into two horns, or arms (see fig. 9), by means of which the fluid is directed to the eggs as deposited. At the writers’ request, Mr. R. A. Cushman has made the accompanying drawing of this organ. The incubation period appears to be longer than in the other species of Amblyomma observed, 91 days being the minimum period recorded. The average mean temperature during this period was 70.19° F. and the total effective temperature 2,474° F. Under natural conditions this period may be somewhat shorter. The records given in the accompanying table were all made upon eggs kept in the laboratory on moist sand. Only a very small percentage of those deposited hatched, many of them being shriveled and black when deposited. TasLE XLV.—Jncubation and larval longevity of Amblyomma tuberculatum. Temperature during incubation. Mini- Eggs. Hatching oe Larval depos All larvee dead. longev- e ited. began tion ity. Maxi- Mini- ae aoe period. mum. mum. aca ie 1908. 1908 Days Days By ot oF oF Aug. 27 .| Dec. 4...-: Dec. 22, 1908. ....-.- 1 97.5 34.0 70. 26 2,726 Aug. 29 .| Nov. 27 91 Mar 2-17, 1909. 95-110 97.5 34 70.19 2,474 Aug. 31 .| Dec. 4 96 Dec. 22, 1908. ..- 7.5 34.0 69. 63 2, 557 Sept. 1 Dec. 4.. 95 Mar. 3-20, 1909... 94-106 97.5 34.0 69. 47 2,515 Sept.7 Dee. 4-29. 114— | Jan. 13, 1909.......- Bate [oes onions Sl Sea Ole aaine ae) aaeeae ee The larva (Table XLV).—The greatest larval longevity observed by us was between 95 and 110 days. None of the lots, the longevity of which is recorded in Table XLV, contained more than 200 speci- mens and the three lots which had a longevity of from 15 to 18 days eee ee ee THE GOPHER-TORTOISE TICK. 127 each contained only one or two larve. Three slightly engorged larvee collected from a rabbit on December 21, 1907, were placed upon a bovine on March 10; two were found attached the following day, while the third was found dead on March 12. While the two ticks remained attached for only a few days, the fact that they reattached shows the possession of considerable vitality. A few specimens of a lot of larvee from one-fourth to three-fourths engorged when col- lected November 30, 1908, lived for three months. . Engorged larve taken from a rabbit on December 21, 1907, and kept in the laboratory at a mean temperature of 61.4° F., did not com- mence to molt until 86 days later, having required a total effective temperature of 1,583° F. Engorged larvee collected in November began to molt in from 107 to 147 days. On the dog no particular preference as to position of attachment was observed, but on the rabbit the larvee were found in great patches near the base of the ears, a few being in and on the ears. Larve have been taken in abundance on dogs and rabbits and a few speci- mens on cattle and sparrowhawks. The nymph (Tables XLVI, XLVITI).—On June 8, 1909, one nymph was alive in a tube which contained 8 specimens that molted from larvee between March 15 and March 30, 1909. This individual had lived between 70 and 80 days up to the time it was put on a host Bie Rev (June 8). One nymph which “tended between the seutam and eapitulum molted March 11, 1909, was alive in position to receive an egg from the oviposi- Bunrapletoattach tow fost when ee applied on May 31, 1909, a period of 81 days after molting. Other lots which molted in March, 1909, and were kept on sand died in from 27 to 56 days. It should be stated that all of these nymphs were collected as larve late in the fall of 1908 and did not molt until March. Probably specimens dropping during warm weather so that they would molt to nymphs in a short time would live for a much longer period. Nymphs were found to attach readily to a bovine, but some trouble was experienced on account of scabs forming around the mouth- parts and causing the ticks to drop before becoming fully engorged. Specimens were found to change their point of attachment several times before imbibing much blood. The shortest period in which engorgement took place upon a bovine was 8 days, the greater number dropping on the ninth and tenth days, the last to leave the R 128 LIFE HISTORY OF NORTH AMERICAN TICKS. host dropping on the eleventh day. Upon a cold-blooded host the period of engorgement will undoubtedly be found to be much longer, as was found to be the case with Ambylomma dissimile. Attempts to get nymphs to attach to a horned toad were unsuccessful. TABLE XLVI.—E£ngorgement of nymphs of Amblyomma tuberculatum. Nymphs dropped engorged—days following application. Re Date nymphs applied. Host. ae ag 1/2/314/5]/6]7{18]9]10/1| Ped SADT Ae OOS ie. Seam a. cents ntain (emi Bovine....} 0 0 0 OF} Ok Ont cOn OF Gul: 75 2 7 aot USS LOS cla tera sis ernie eral aisle Poin seeedOwnens 0 07 OF OF On) “One 1 2 Ej eee 8 SEES SAT) Re AM A CE Wiadast + 00:58 ow oteeh ol i el Bile 10 Lie Lk 0 eh. BRSSER AME SPARSE ABR SA ee neler eayches OOP GE Onan SOR a Oras oO} O] 06 1 FOR Rte Re a a RE et igs o| o| of of of of of of of 1] 2 3 At a mean temperature of 81° F. nymphs which dropped the last of May commenced. to molt in 29 days, a total effective temperature of 1,104° F. having been required. The molting period of nymphs which become males and females is about the same. It was found that when the engorged nymphs were placed in tubes on moist sand they at once burrowed. into it out of sight. When examined they were found an inch or more beneath the surface, in which position molting took place. This habit was not observed in engorged larve, but is probably the same. Although observations on this habit have not been made in other species of ticks, owing largely to the fact that it was necessary to keep them on an impenetrable surface in order that the exact dates of molting could be observed, it seems quite probable that some of them may do so also. Such a habit is of great advantage to the tick in protecting it from enemies during the quiescent period, as well as in preventing drying out. TasLeE XLVII.—Molting of engorged Ai of Amblyomma tuberculatum engorged on bovine. Temperature from Engorged nymphs molted—days following drop- | Number dropping to date Die. molted. | first tick molted. Date engorged nymphs Peele dropped. F 3 nesctolaaee Aver- . ||| Maxi-} Mini-| age 29] 32] 36] 37| 38) 39] 44) 46] 48] 49] 51] 53) 66)203/207 3 E a mum. | mum. | daily siecle mean. i sa 0! 5a 4 Apr. 23, 1908 1] 0} OF OF OF OF OF OF OF OF OF OF OS} OF OF 1) OF} YY 91.5 47| 76.29 Apr. 24, 1908 Go} of of of 0} of o| of oiiad is|lua} of of of 21 4! 6} 30 47| 74.72 Apr. 25, 1908 5} 0} O} O] OF OF OF} OFI29 BLS Oo; oO} Oo; OF} 1] 3) 4) ~~ «89 47| 74.73 Apr. 26, 1908 21D) 0}. O}...0) .0)..0)* 10). 0}, OL 91 0) Seo Op Ote Ole iO) Did 91. 5) 47| 75.11 ay 28, 1908 LO) OF OO “0! OF OF Ol Ol OF Oo) Olu Gr Lh 0; of 91.5 69] 80.50 May 29, 1908 4} 0} of19] ol1g|t9l19] of of of of} of of} oO} of i] 3] 4} 91.5 69] 80.61 May 30, 1908 311d} Cl Oj; O| 0] OF OF OF OF OF OF OF OF OF OF 1] OF 1 91.5 69] 81-05 May 31, 1908 2 Ole O11 SILO ]..0}. O}- O} 0} OG} .0},..0), 70) (ORO). 0) AIF Bl, 2) 9 Sie 69} 81 Nov.24, 1908 1] 0} OF OF OF OF OF OF} OF} OF OF OF} 6} OF} OG} OF 1) 1) 100 17) 67.15 Dec. 2, 1908 1} 0} O} OF OF OF OF OF OF OF C] OF OF ODIs) OF 1) OF 1) 100 17| 67.89 May 21, 1909 1119] O; O} OF OF OF OQ OF OF OF OF OF OF] OF C] OF 1] 1) 100 47| 86.17 May 22, 1909 20), SL}, 10) 10), 20) GO Ole Ol. Clad GO}. Gl Ol OLS 2}. 1’ 100 47| 86.56 Total..| 28)...|...|...|. al Pa 9| 14] 24 THE GOPHER-TORTOISE TICK. 129 The adult—Among the individuals observed to molt to the adult stage there was a predominance of females. The greatest adult longevity observed was about 90 days; other specimens lived from 17 to 76 days. All of these records were made during midsummer. A few ticks of both sexes remained active, when kept in tubes in the laboratory, for more than 2 months during the summer before being placed upon a host. It is certain that with abundant material, placed under natural conditions, adults would be found to live much longer than those observed by us. Several males and 3 females placed upon a tortoise on July 29, 1908, readily attached. The first female to engorge dropped 20 days later, measuring 24 by 18.5 by 11 mm. Next to Amblyomma varium, which has been recorded by Robr (1909, p. 120) as measuring 28 by 24 by 15 mm., this is the largest tick on record. The second female dropped engorged on the twenty-first day after attachment and measured 19 by 13.5 by 10 mm. The third female dropped on the twenty-fifth day after attachment and measured 19 by 13.5 by 8 mm. During the period of attachment none of these females was observed in copulation. Upon removing the first female from the bag in which the tortoise had been placed it was found apparently in copulation with a male which had also dropped from the host. This fact suggests the possibility that copulation takes place after the female drops engorged. Males have been observed to remain attached for a long time after the females drop, and this habit accounts for their being more com- monly met with upon tortoises. One of the three males which at- tached to a tortoise July 29, 1908, remained. on the host 43 days after the last female dropped and the other was still attached but dead when the tortoise died on January 5, 1909, thus having been attached 135 days after the last female dropped, or a total period of 160 days. The males attached to the margin of the shell as well as to the body of the tortoise. It is conceivable that the females may also . thus attach to the shell, but if this actually occurs the period of en- gorgement must be greatly prolonged owing to the poor blood supply. Attempts to secure the attachment of adults to horned toads (Phrynosoma cornutum) were unsuccessful. LIFE CYCLE. Larve may live for at least 95 days during the winter months. The period required for engorgement has not been determined. At winter temperature in the laboratory at Dallas 86 days passed before molting commenced. During this period a total effective temperature of 1,583° F. was accumulated. The longest molting period recorded was 165 days. The greatest nymphal longevity 21448°—Bull. 106—12—__9 130 LIFE HISTORY OF NORTH AMERICAN TICKS. recorded was 81 days. At the end of this period one specimen was still able to attach to the host. On a warm-blooded host the nymphs may engorge in 8 days and molting may commence as soon as 29 days after dropping. that in the adult stage it is found on no other host than the rabbit, while the adults of other species of the genus Dermacentor are very rarely found on that host. DESCRIPTIVE. Adulé (Pl. XIII, figs. 3-5).—Males from 2.5 by 1.25 mm. to 3 by 1.75mm. Females, unengorged, 2.5 by 1.5 mm. to 3.75 by 2 mm.; engorged, 10 by 7 by 3.5 mm. to 15.4 by 10.7 by 7.7 mm. The males have interrupted white markings along the lateral borders of the dorsum. The posterior border of the scutum of the females is. white, the lateral borders with interrupted white markings. In both sexes the outer surface at the apex of the leg segments is marked with white, in which are usually two dark red punctations. Some specimens from California, Oregon, and Utah have no white visible, while others are nearly as strongly marked as those from New Mexico and Texas. Nymph (Pl. XIII, fig. 2)—Unengorged, about 1.23 by 0.79 mm.; engorged, 3 by 2.1 by 1.2 mm. to 3.9 by 2.8 by 1.6 mm. Color, unengorged, reddish brown; engorged, dark slate to almost black. Capitulum 0.305 mm. long (from tip of palpi to base of emargination of scutum); scutum 0.524 mm. long by 0.521 mm. wide. Larva (Pl. XIII, fig. 1)—Unengorged, about 0.686 by 0.433 mm. (alcoholic) ; engorged, 1.3 by 0.8 by 0.7 mm. to 1.5 by 0.9 by 0.8 mm. Color, unengorged, reddish yellow; engorged, dark slate. Capitulum 0.148 mm. long (from tip of palpi to base of emargination of scutum) ; scutum 0.260 mm. long by 0.344 mm. wide. Egg.—Ellipsoidal, yellowish brown, shining, smooth. The average size of 10 measured was 0.65 by 0.47 mm. HOST RELATIONSHIP. The host of the type variety is the jack rabbit. The types of the species (D. parumapertus) are labeled as taken from man and in a chicken house. Nospecimens of this variety have been taken on other hosts than jack rabbit and cottontail rabbit. While very few larve and nymphs have been collected on rabbits, it would appear from the fact that no specimens have been taken on any other animal that the rabbit is the principal host of those stages. We have en- gorged larvee in our rearing experiments on the fox squirrel, guinea pig, and bovine, as well as rabbit, and nymphs have been engorged on the guinea pig and rabbit. Although a large number of unengorged adults have been col- lected, very few fully engorged females have been obtained. It would seem that a large number of them are scratched off by the host before becoming replete. The species is found principally in the ears of 160 LIFE HISTORY OF NORTH AMERICAN TICKS. the host, but it also attaches on the outside of the ears, on the head, on the neck, and sometimes between the toes. Adults collected on rabbits have been found to attach readily to bovine hosts and to engorge to repletion. een, oo Fia. 13.—The rabbit Dermacentor, Dermacentor parumapertus marginatus: Distribution. The large dots show localities where the species has been collected in our investigation. The small dots indicate the probable range of the species in the United States. (Original.) GEOGRAPHICAL DISTRIBUTION, . (Fig. 13.) Mesa City, Arizona, is the type locality for this variety. The species is confined to the semiarid and arid west, including Texas west of about the 101st meridian, New Mexico, Arizona, southern Utah, Nevada, California, and southeastern Oregon. It appears to Bul. 106, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE XIII. THE RABBIT DERMACENTOR, DERMACENTOR PARUMAPERTUS MARGINATUS, AND THE TROPICAL HORSE TICK, DERMACENTOR NITENS. Dermacentor parumapertus marginatus: Fig. 1.—Unengorged larva. Fig. 2.—Unengorged nymph (balsam mount). Fig. 3.—“Deposited-out”’ female, dorsal view. Fig. 4.—Male, dorsal view. Fig. 5.—Unengorged female, dorsal view. Dermacentor nitens: Fig. 6.—Unen- gorged larva. Fig. 7W—Unengorged nymph (balsam mount). Fig. 8.—Engorged female, dorsal view. Fig. 9.—Male, dorsal view. Fig. 10.—Unengorged female, dorsal view. Fig. 11.—Engorged nymph, ventral view. Fig. 12.—Engorged nymph, dorsal view. Fig. 13.— Engorged female, ventral view. Fig. 14.—Male (balsam mount). (Original.) [ea 4 | ¢ i : earns » ho Sr > ry ey » ae —_ -.- THE RABBIT DERMACENTOR. 161 be most abundant in western Texas and in New Mexico. Larve and nymphs have also been taken at Monclova, Mex. LIFE HISTORY. No observations on the biology of this species have been previously published. The egg (Table LX XI).—In July at a mean temperature of 85° F. oviposition commenced as soon as the fifth day after dropping. Four of 7 ticks which dropped engorged during July and early August com- menced oviposition on the fifth day, the three remaining ones com- mencing a day later. The average oviposition period of 7 females observed in July and August was 15.9 days. The minimum, oviposi- tion period was 11 days, within which time 855 eggs were deposited; the maximum, 26 days, during which period 3,247 eggs were laid. The maximum number of eggs recorded for the species is 4,660. The female which made this record deposited 918 eggs during one day. The females died in from 1 to 6 days after deposition was completed. One of the 7 engorged females upon which these counts of eggs were made was collected on a rabbit, while the other 6 females were engorged upon bovines. The measurements of the 6 were as follows: 10 by 7 by 4 mm., 12.5 by 9 by 6.5 mm., 12 by 8.5 by 6 mm., 11 by 7.5 by 4mm., 10 by 7 by 5mm., and 10 by 7 by 3.5 mm., respectively. The shortest incubation period was 20 days, the mean tempera- ture during this period being 85° to 86° F. A total effective tempera- ture of at least 850° F. appears to be required for embryonic development. TaBLE LXXI.—IJncubation and larval longevity of Dermacentor parumapertus margin- atus. | Temperature during incubation. Eggs depos- | Hatching be- ee All larvee Larval ‘ as ited gan. incubation dead longev- : ., | Average |. rotal ¢ ; period. CN ity. Maxi- | Mini- | * aily effective mum. | mum. c tempera- eee ture. Days. Days °F. ot Bras <7 June 30,1908 | July 23,1908 7 ene eae rac (Seer ee 95 70.0 81.1 954. 25 July 2,1908 | July 24,1908 Zari Seeper ae Bae see | Sas eee see 95 70.0 83.1 959. 75 July 18,1908 | Aug. 8,1908 22 | Jan. 25,1909 170 99 76.5 85.5 935. 75 July 20,1908 | Aug. 10,1908 22 | Nov. 30,1908 102 99 73.0 85.4 916. 75 July 22,1908 | Aug. 12,1908 22 | Mar. 6,1909 223 99 73.0 85.7 922. 75 July 24,1908 | Aug. 14,1908 22 | Mar. 12,1909 227 99 73.0 85.9 944.75 July 26,1908 |....- ois 22% 20 | Feb. 10, 1909 197 99 73.0 86.2 863. 75 July 27,1908 | Aug. 16,1908 21 | Oct. 26,1908 71 99 73.0 86.3 909. 00 July 28,1908 | Aug. 17,1908 21 | Feb. 15,1909 227 99 73.0 86.4 911.50 July 30,1908 | Aug. 19,1908 21 | Mar. 12,1909 222 99 73.0 86.7 917. 25 Aug. 3,1908 | Aug. 22,1908 20 | Dec. 6,1908 106 99 73.0 86.2 863. 50 Aug. 5,1908 | Aug. 24,1908 20} Mar. 9,1909 214 99 73.0 85.1 857. 25 Aug. 8,1908 | Aug. 28,1908 21 | Feb. 17,1909 167 96 73.0 $49 878. 25 Aug. 14,1908 | Sept. 4,1908 22 | Feb. 5,1909 144 96 75.0 4 908. 50 Aug. 16,1909 | Sept. 8, 1909 24 Mar. a 193-221 110 77.0 89.38 | 1,112.75 7,191 Aug. 14,1909 | Sept. 3,1909 21 | Nov. 18,1909-]| 76-144 110 77.0 89.51 976. 25 Jan. 25, 1910 The larva (Tables LXXI-LXXIII).—The greatest longevity of larve observed by us was 227 days. Engorgement has taken place as soon as the fourth day. Asisshown in the last record in Table LX XII, 21448°—Bull. 106—12 ll 162 LIFE HISTORY OF NORTH AMERICAN TICKS. the longest period of engorgement observed was 14 days. In this case the larvee were scratched off when between one-fourth and five- sixthsengorged. Six of the 8 were engorged sufficiently to molt. The first lot recorded in the table did not attach readily and for this reason those ticks which did not take hold at first were allowed to remain in the bag. Thus the larve which dropped on the ninth day probably did not attach until the third day after application. In the third lot recorded in the table the squirrel escaped from the cage on the afternoon of the fifth day after the ticks were applied and was not put back until the next morning. There is little doubt that some larve dropped in the meantime. TasLeE LXXII.—Engorgement of larve of Dermacentor parumapertus marginatus. Larve dropped engorged—days following appli- cation. Total Date larvee applied. Host. Caner V2) (OB 4 | BOT) 7) |e he a ean ease ATI seb as cine acinace net cies Bovine....... On VO SOU Oi LO Bath ot, AL One 0 13 NER DOTA GORE Se secs cise cle ce tele cl ates. GOstaeenes OFA ON ON MON ea Orit Ol "O51 Or =O 9 Ochs iNOS 5 a ee eet oe Squirrel....... Oo Os On 2 oa alae O On On ae 23 INOVst4E IO00 oS Stet seen cee. Guinea pig= 2.) ONO OU On rare Seal aE On 10 20 Wears Wl SOLO opie te Soe clesoes| eases Gossee sce! | ol OO Olea Ol Sl OW Bye 6 (SL SF OG 24 Hel eee Sae Rniaceoecy lacerc Gowaceriee OF VOR PRON ONS Os On etn Ona 1 kO slates 8 At a mean temperature of 87° F. molting occurred on the eighth day, an effective temperature of 350° F. having accumulated. TasieE LXXIII.— Molting of engorged larve of Dermacentor parumapertus marginatus. Temperature ; from drop- Engorged larvee molted—days following dropping. 3 ping to date rst tick Date 2 molted. en- is g gorge Deve Host. . 3 b dro Ate lox ped. eS g/eldic F 2 8 | 9 |10]11]12} 13) 14} 15] 16] 19} 20] 21 | 23} 24] 26) 39} 47) = E 3 | a : 4/84 =} ols | > A HiAala-i Aal\Hiq!] & a |< 1910. | eur | Sr eae June 12, p. m....| Guinea pig... . UR ate Sere (eae es acl ener ~--|---/19]..-| 1) 1} 103 | 77.50) 90.10 Silly 22/a1m -.-.|....dor..--.-.|)) 4 ales 19)...-{7g|t..... 1) 2} 3] 103 | 77.50! 90.19 Ruly 22 pi m..-.|...--docc (Le. 2.] @ ae 1} 3| 4| 98 | 66 | 69.36 Tuly 3, a.m ....|..:..do....-..-- Freraeuicelpalaghort... va 2) 1| 3] 103 | 79 | 90.27 Baty Oa atatieses|e. vidos bet! Bl 03 \ig re) ee 1} 4| 5/103 | 79 | 90.23 A ean ae do At ae els dl Leal 3) of 3] 103 | 79 | 90.21 ea En do fe .4 Cs aces ioe ee AS 1] 0} 1) 103.5] 79 | 91.04 megonom....-|. <2 Rt ep (ecm a ce | 2|?| 3] 103.5] 79 | 91.18 ‘Aug. 2,a.m..... Rabbit........ qc OS eal £9 a (a aa | o| 11 1} 103.5] 79 | 91.00 ESA en es A el i) dete Aug. 10, a.m....] Rabbit........ gaia es Pee a | 9} ol 2| 104.5| 79 | 92.32 Me tp m...-|..-..d0-:-.-. =<. 10/29 ig 5g i$ \i9 5 A ia 4 6] 10| 104.5| 78 | 92.38 Aug. 11, a.m....|..... do 10 Jiglig 2g hie Rolee .| 3] 3] 6] 104.5] 73 | 91.32 Aug. 11,m.noon.|.....do.......-- H1g-.-{18|-- © i3|} | 3] al 5] 104.5] 79 | 92.44 Aug. 11, p.m....|.....do.........] 13}---|1 9439] 98 iglhe | 6] 6 12] 104.5 79 | 92.13 Aug. 12,a.m....|.....do......... 12119]...| 24] @) Isha 19|...|...| 4] 5] 9] 104.5] 80 | 91.96 Hugin pm -_0:|!..fsao.2e ide Loe lds. i8 \og 13] 19]...|...]...) 2] 4] 6| 104.5] 73 | 90.53 Rupee) 2 | esido. 215 dGca A. () ight Hy lide... _..|...! a} a} 2} 104.5] 73 | 90.15 Mapes pte. os tds<.t- balk cag Blea. Les A lelighl ake ...[..-| 4) 11 5] 104.5] 73 | 90.15 cul 1s A piel Ms Pe an a RI | in We i | af o| 2] 104.5] 73 | 89.67 Total... 103... a Ae ey he .| 49] 40] 86|......|.-2--- = 1 The ticks which molted on this date are included with those recorded on the following day. In August, 1910, at a daily mean temperature of from 91.96° to 92.44° F. molting commenced on the thirteenth day. The longest period from dropping to molting was 22 days. This occurred at a daily mean temperature of 69.36° F. The males and females began to appear about the same number of days after dropping. The weighted average molting period of 42 nymphs which transformed to males was 15.89 days. In the case of 40 females this average was 16.22 days. The weighted average period from dropping to molting for all nymphs observed was 15.62 days. A total effective tempera- ture of 636.5° F. seems to be required for this transformation. The adult (Tables LX XXVITI-LXXXIX).—The number of males and females which molted from nymphs was practically equal. The greatest longevity which has been observed was 359 days. This record was made on a lot of 29 males and 29 females which molted from nymphs August 10, 1910. The last male in this lot died May 31, 1911. It had lived 294 days. The females appear to have a slightly greater longevity than do the males; this is particularly noticeable 188 LIFE HISTORY OF NORTH AMERICAN TICKS. among those ticks which have once been attached to a host in the adult “stave. Hot weather also appears materially to shorten the longevity of both sexes. Taste LXXXVIII.—Longevity of adults of Dermacentor occidentalis. Number. Date molted or collected. All dead. aay Male. | Female. 1910. Days. Molted only, 42sec. seen --sa5 2-6 beh 0 1 |, Oct. 18=Nov.i28, 1910 set sh ee asec 106-147 Molted, Aug. 10.- 29 ZOOM PAUE. 4 SOll cc. cee aeeee see ee 359 Molted, Aug. 15.... 1 Pee re May: 27, Olt Sice se oeeek eee cee 285 Moltied. Avg. 15-2052 | fe. 2 ce ac = 2 2 May SsLOUe ts 2 foes a ee eee eee 266 MOA ATE dpe ere one ees 0 1 Nov, 28-Dec::20, 1910... ..2 ncaa 103-125 Molted, TORO). Jai. SO Sen 2 OU May 20; 1911. co.cc em aee eee oes 26! Collected, SAUDI peat ates aee nods en 0 1 Sly LO Aue 8 O10! ace eee ee 118-147 DOtee eas cree. Saeko eee eee 1 MIT ¢ COLOR Se aac ns cc aetettaters i= Collected; Apryos. 2: sce. -4- = se ne 2 Si) Aug. 18-3), 191022. cotett cee cee 135-148 Collected, AIS cee seco oss a osene 8 4| June 18-July 18; 1910 eee adacsat 71-101 Collected, WA DTS ste cae = Bice cssme 0 5 | July 18-Aug. 18, 1910; inn oo 82-113 Collected, May 28 saneacee. oe sere 0 2 5dO\2). . a vecpatnute eee ee as caeeee 51-82 Collected, OY. a Dae ie ee eee ae 6 5 Apr. Si MOM. See GOES cee 166 Collected, CO CERIGL Ue | eee cert: 0 1 | Mar. 20, TOU Soe bee ees ees 145 Copulation of this species has not been observed before attaching to a host. any time between one and several days after attachment. Mating has been seen to take place upon bovine hosts In one case a female became fully one-half engorged before she was visited by a male. One female which was not observed to be fertilized became nearly engorged and dropped in about the normal engorge- ment period. However, no eggs were deposited by this individual. Tasnte LXXXIX.—Engorgement of adults of Dermacentor occidentalis on bovines. Females dropped engorged—days following attachment. Date females |Num-| State of en- State of en- applied. ber. | gorgement. Date attached. Total | gorgement. 2] 4)]6)] 71 9 J10 |17 | number dropped. 1910 1910 IAIN s Ooccsscsscst- 5 | Slightly to} Apr.9 -......--- oT ees |beae 1| Fully. one-fifth. 1.55 0) sy -) Seete e ae 2) Wnengorpeds| Apr. 22) OO 0) wai cOles <0) Ol” Diet 1 Aug. 28, 1909............| Squirrel... fetch Ol ennO| eee FOI nO| pe O|(2- Ol DO} enh Oluuard 1 Total .... LD Eales [teal fe matt S05] Sayers SOSA solooce A a 11+ 1 Collected from a swamp rabbit. The adult (Table XCV).—The maximum adult longevity observed by us was 233 days. This record was made on a single female which became adult September 13, 1909. A female which was collected on an opossum May 10, 1910, lived 202 days, and one male in a lot con- sisting of 2 males and 3 females, which were collected on a squirrel April 6, lived 106 days. Other lots of collected individuals lived from 15 to 93 days. Ifa large number of freshly molted individuals were kept for longevity tests without allowing them to feed it is probable that some individuals would be found to live longer than any observed by us. Tn our observations mating has been preceded by a period of feed- ing of from 3 or 4 to 10 or more days after attaching to a host and s 196 LIFE HISTORY OF NORTH AMERICAN TICKS, has continued for a day or so only. Females have been found to reattach even when engorged to a considerable extent. Unengorged females taken from dogs to which they had attached, and on which they had probably mated, engorged as soon as 5 days. Nine days was the shortest period in which previously unattached females engorged. Morgan, however, states that females engorge in from 5 to 8 days. During engorgement the females constantly excrete what appears to be undigested blood. The adults also void considerable excre- ment soon after molting from nymphs. A male which, with a female, was placed upon an ox November 1, 1907, remained upon the host, frequently changing its position, until February 14, when it was found attached but dead. Thus it remained upon the host for 105 days from its attachment and 91 days after the female had dropped engorged. Other males have disappeared from the host on the eighth day after the females dropped. TaBLE XCV.—Engorgement of females of Dermacentor variabilis. Females Period Adults applied. Host. dropped of attach- Size engorged. engorged. ment. Days INOW,-11 1907. «sa cece Bovine Sees sae eece INOve bicep 14 | 13 by 9 by 5mm. Mar 23. 108s caf 1a eaan 3| sewers COSece ose Sac eee ies De scones 9 | 12 by 9 by 5mm. June og 1903 sch er bas ifovine\Geattactied).. June 24 5 | 13 by 11 by 7 mm. bi dadsinc atic nejseicel ae asedOsaceswiass someones JUNC Zee cee oe 6 | 13 by 11 by 7.5mm. 12 by 9 by 6.5 mm. 12.5 by 9.5 by 8mm. DOs sso toet eiosscscc|ecsce Gos toss foccaeeesee June 26 (5).... 7 {13 by 10 by 8 mm 13 by 9 by 7mm 13 by 10 by 7 mm. 1D es Sser ear Soecocce BOWING. 252 csc esee ce cos June 27........ 8 | 12.5 by 10 by 7.5mm, Aug. 24, 1908 (slightly | Bovine (reattached)...| Aug. 30....... 6 | 12 by 7 by —mm. engorged). PAN P Da OUR Coe cee = cl ea oe COBRER RAE ono ccrase JANIE Blas sate oe 7| 10 by 7 by 5mm. Apr. 19, he ae oe ee GOs semen oneeatae PAU Ais ctses- 8 | 13.8 by 9.4 by 7.3 mm Sept. 8, 11" a ne ea 6 (0 Be nea Sept..16:: 2... 8 | Fully engorged. DG ee eee cccktess see doles. see Bepeswdcccesee 9 | Partly engorged. Mar 726; 09102-22220 Seearse. CORE saaarperanesee oN, 0) pi eee 16 | One-third engorged. | LIFE CYCLE. Larve may live for 335 days; they may engorge as soon as 4 days after application to a host and molt as soon as 7 days after dropping, a total effective temperature of 306° F. being required for molting. Nymphs may live for from 7 to 8 months; they engorge as soon as 4 days after attachment and may molt as soon as 16 days after dropping. A total effective temperature of about 741° F. appears to be required for this transformation. Adults may live as long as 233 days; they may engorge in 8 days (5 days ?) and commence ovipositing as soon as 5 days after dropping. As many as 7,378 eggs may be deposited. Embryonic development may be com- pleted in 20 days, a total effective temperature of 825° F. being required. THE TROPICAL HORSE TICK. 197 Adults of this tick have been collected on animals in Texas at all times of the year. However, they appear to be most abundant in the spring and early summer. Nymphs have been collected on animals in considerable numbers in February, March, and April, and in one instance in August. With little doubt the immature stages are to be found on hosts nearly all the year round. ECONOMIC IMPORTANCE. Aside from the fact that this species occasionally attaches to man and domestic animals and often causes considerable annoy- ance, it is of no economic importance. The ticks are easily removed from a host and their attachment has not been known to produce any serious Consequences. NATURAL CONTROL. The many bird and other enemies of the cattle tick undoubtedly prey upon this tick also. Dogs have been observed by us to crush them with the teeth, both when attaching and after dropping. ARTIFICIAL CONTROL. This species has not been found to occur in numbers except upon the dog and some wild mammals. When dogs become badly infested the ticks may be removed by washing the dogs with one of the standard tick dips. Ordinarily hand picking will suffice to keep them in check. THE TROPICAL HORSE TICK. Dermacentor nitens Neumann. The common name of this species is derived from the fact that its distribution is restricted almost entirely to the Tropical Life Zone and that the horse is its principal host. DESCRIPTIVE. Adult (Pl. XIII, figs. 8-10, 13, 14).—Males 2.5 by 2 mm. to 3 by 2mm. Females, unengorged, 3.25 by 1.75 mm. to 3.5 by 2 mm.; engorged, 9 by 7 mm. to 12 by 9 by 5mm. _ Both sexes are reddish brown and without white markings. Nymph (Pl. XIII, figs. 7, 11, 12).—Unengorged, about 1.33 by 0.9mm.; engorged, 2.9 by 1.8 by 1mm. to 3.5 by 2.2 by 1.3mm. Color, unengorged, pale brownish yellow; engorged, dark gray. Capitu- lum, 0.359 mm. long (from tip of hypostome to base of emargination of scutum); scutum 0.54 mm. long by 0.641 mm. wide. The shape of the nymph, particularly when engorged, as with the engorged female, is quite typical of the species; the greatest width is at the 198 LIFE HISTORY OF NORTH AMERICAN TICKS. third pair of legs, from which the body is very noticeably constricted posteriorly. Larva (Pl. XIII, fig. 6).—Unengorged (in balsam), 0.714 by 0.470 mm.; engorged, 1.5 by 0.9 by 0.6 mm. Color, unengorged, yellowish brown; engorged, steel-gray. Capitulum 0.205 mm. long (from tip of hypostome to base of emargination of scutum); scutum 0.290 mm. long by 0.372 mm. wide. Egg.—The average size of 10 eggs measured was 0.565 by 0.419 mm. Color yellowish brown to brown; shining, smooth. HOST RELATIONSHIP. The type host of this tick, the horse, is the principal host for the species. This tick has also been taken from the ears of the mule at Brownsville, Tex., and at Tampico and Victoria, Mexico, Bishopp found it commonly in the ears of both the mule and the ass. It prefers the inside of the ears as a place for attachment. Hooker has found a number of specimens attached in the horse’s mane between the ears and several to the belly. This, however, was due to the fact that the ears were literally filled with ticks so that there was no place in the ears to which they could attach. In Texas several larve have been taken from the ear of a goat. The tick has also been taken from the ears of the ox and of a calf. A single specimen in poor condition, but apparently of this species, was taken at Kerr- ville, Tex., by Mr. F. C. Pratt from a deer skin that had been removed in January. In our studies we have found them to attach to the scrotum of a bovine and develop to engorged adults. * GEOGRAPHICAL DISTRIBUTION. (Fig. 17.) Jamaica and Santo Domingo are the type localities for this species. In the vicinity of Brownsville, Tex., it is an important pest to horses which run in pastures; it has also been taken at Harlingen and at Corpus Christi, Tex. A single specimen which appears to be this species was collected at Kerrville, Tex., but the species has not been found during subsequent collections in that vicinity. There seems to be much doubt of the correctness of the record of this species from Arizona. The tick was found in abundance at Victoria and Tampico, Mexico, but careful search for the species failed to reveal its presence on the plateau in the central and northern parts of that country. It has been recorded from Guatemala, Panama, and Costa Rica in Central America and from Cuba, Jamaica, Haiti, Santo Domingo, and Trinidad in the West Indies. It appears to be a serious pest in Cuba and Jamaica. . THE TROPICAL HORSE TICK. 199 LIFE HISTORY. Observations on the biology of this species have been published by Hooker (1908) and by Newstead (1909). The egg (Table XCVI).—The first 3 ticks the oviposition of which was recorded were collected from the ears of a horse; the next 7 were ee, se. = ; = en Ss : Fic. 17.—The tropical horse tick, Dermacentor nitens: Distribution in North America and West Indies. The large dots show localities where the species has been collected in our investigation. The small dots indicate the probable range of the species in North America and the West Indies. picked from the ear of a mule; and the last 2 dropped from the ear of a bovine. The preoviposition period in the 12 ticks recorded varied from 3 to 15 days. The minimum period occurred in the case of 2 females 200 LIFE HISTORY OF NORTH AMERICAN TICKS. which dropped from a host on July 27. These ticks were kept at a mean temperature of 85.4° F. The period of deposition ranged from 15 to 37 days. The length of this period, as well as that of the preovi- position period, is materially affected by temperature, the high tem- peratures producing the shortest periods. The maximum number of eggs deposited by 1 tick was 3,392 in the lot of 12 females observed; the average was 2,784. | The minimum incubation period for eggs in the laboratory at a mean temperature of 85° F. was 24 days. An effective temperature of 935° F. appears to be required for incubation. TaBLE XCVI.—Preoviposition, incubation, and larval longevity of Dermacentor nitens. OUT OF DOORS. Temperature during incubation. Date : ie engorged| Eggs |Hatching raped si eels female |deposited.| began. period. aeaal gevity. Maxi- | Mini. | Average | Total dropped. : mum. | mum. ay psec 1908. 1908. 1908. Days. 1908. Days. oi Cir. CRs Se ee 22 a 29|} June 5 38 | Aug. 15 71 91 43 73.2 | 1,149.2 (1 Pes Ieee! (0 ee ane June 6 39 | Aug. 7 62 91 43 73.5 | 1,187.7 May 17] May 21] June 20 31 | Aug. 14 55 93 62 79.3 | 1,125.3 May 18| May 26 | June 24 30 | Aug. 15 52 96 62 80.4 | 1,120.6 May 19 douss<* June 26 32 GOs" 50 96 62 80.3 | 1,195 ay 2 May A ae 28 3 oe 9 aa Bs ga 80.3 | 1,232.5 ay 22 ay 2 ObaaSe ug. 28 6 80.3 | 1, 268.2 May 26} June 2] July 1 30 | Aug. 29 59 96 62 80.5 | 1,124.9 IN THE LABORATORY. 2|June 1 3l 87 56 75.2 999 3 | June 3 32 88 56 75.8 1,049.5 9} June 5 28 88.5 65 Ti.5 966 10 | June 6 28 88.5 65 77.8 957 13} June 8 Poy fig |L es Ses 3 IS eee ae 90 65 78.3 952.8 14) J ane 9 ef en Sel | ee 90 e 78.7 963.3 15h peeaOness Gy Sowa se ee oo ee 90 7 79 935.3 31} Before Less than 30): -Dec:5s) About 98-52. -7<..|5 sss —e en oe ae oe Eee Aug. 29 2,|...d0..2. -| Lessihan'28' |) Nov. 260) Aihowt)89)| 52. -2.2252 | aoe asec |o seca te | See 6 | Aug. 2 24] Nov. 26-| 89-117 99 73 85.25 | 1,014 Dee. 24 9} Sept. 1 24 | Oct. 26- 55-77 96.5 73 84.4 1,000 Nov. 17 The larva (Tables XCVI-XCVIT).—As is shown in Table XCVI, the longevity of larve which hatched in June and were kept in tubes under the most favorable conditions was only 71 days. All of the Jarve from eggs of females which dropped in May were dead 2 months after hatching. Seed ticks hatching from eggs isolated at daily intervals and kept in tubes in the laboratory were frequently found to die in 10 days or 2 weeks. The greatest longevity of this stage observed by us was between 89 and 117 days. This species, the cattle tick, and another species of Dermacentor (albipictus), which is now being studied, are the only species occurring in the United States, which, so far as known, pass both molts upon the host. As a THE TROPICAL HORSE TICK. 201 result of this habit great numbers of ticks reach maturity and repro- duce, but fortunately there has also resulted a great decrease in the power of the larvee to withstand periods of fasting. As is shown in Table XCVII, larvee may engorge and molt as soon as the eighth day after attaching to a host. The longest period from larval attachment to molting was 16 days. The nymph (Table XCVII).—In two of the three lots recorded in Table XCVII nymphs became engorged and began molting on the seventeenth day after being applied to the host as larve. In the third infestation nymphs began molting to adults on the twenty- fourth day after being applied. The period from the molting of the first larvee to the molting of the first nymph was 8 days in one instance and 9 days in the other two cases observed. In one instance the nymphal period appeared to have been only 7 days. The adult (Table XCVII.—The mating of males and females of this species, which molted on the host on the same day, took place as soon as the second day following and was continued until the engorged females dropped. This habit appears to be similar to that of Mar- garopus annulatus. A male Amblyomma americanum has been found attached beneath a female of this species, the ventral surfaces being in apposition as though in copulation. The sexes remained in this relation for only a short period. Likewise males of Margaropus annulatus australis and Dermacentor variabilis have remained mated with females of the tropical horse tick for a number of days. Several females have engorged and dropped, apparently without having been fertilized. One unfertilized female remained attached from the time it molted on May 6 until May 26, when it dropped unengorged. A second unfertilized female which molted July 18 dropped August 11 when only slightly engorged. Females have engorged as scon as 9 days after molting or 26 days after attachment to the host as larve. The longest engorgement period observed was 23 days after molting, or 41 days after being applied to the host as a larva. Females collected at Brownsville, Tex., in November have reattached to a host 3 days later. etwot st. Qesk. 2.0.2 c-8< 28-29 adit, deseripin eaters ss seco ciid ole. 123-124 lifechastory: 2 oss. tees Dowels oe 129 attachment to carapace of turtle......:.........--- ie Gomory, merit te ee epee ee pe eee ew eS 130 GeseriPliVes2. tet eaeoetne oe Meets es... 123-124 distribution, ceberaphicaless.........-:-.-.------- 124 zonal, in North America.....-. Be BES PAE Pa ECONOMILE AIM POLlAN CEs =. 5 Hee eee BGs oo ee 130 ORCLCeeripiyeese o- =~ AU Iee AE oe eae 124 life, histonye: cacseesa Asetleseh. cane. ocene 125-126 epg. deposited: numbers: a. 95052 eet bles. x32 cc 33 hostmelationshijp = ess as ee eer Se 8 124 hostess accidentale:ci= s.r ees wiewed = ee 25 lava ndbesermipiiven cs. weet At oo Oe ol a Ae ee Tiieihistony ee senc 6 wae ee 126-127 Ine eye eng 3 a cet ayes fics eas a eh 2S 129-130 USTORVE Sodexo Rete ees dba 5 ols 125-129 longevity of stages, maximumisiegces seu: -. -. ---- ffl males more commonly collected than nelle eSoEe 7 nymph, -descripiaives: este at oc l cone Sad 124 Nite Wb istory 2355. .eeaee eae ere oye c's 5 127-128 periods in life history, maximum and minimum... 70 vesica biloba and its use in oviposition. ....--.... 73 PETICHH) Da) Leama lite NS al ee ORR es) VR ee 32 MUsHeMMaitOMas. 20S Ibe eek weere pot Sb d 34 eses deposited. maximums ty vefee. oheyeisiev. negates 75 Tum ensneseeo ee susie Weg AS oO 32 Shudiestinw S94 Obey es wee he oe ep ee. tae: AO Ue ROO Dis la asain i et pees ei ish he pentl L Ee Bl ag 123 parva, lareesh tick:on, record : . 2. sxaageres ee Geta 129 studies in 1909.. Bee Betabdis hy wa il ealaaes Anaplasma causing fever in bovines, Poni By Mar PAO PURE sae ee eee = 111 Ppeaeberons eke. mene x era ci apt ae th cena anh Bef 44 Ani. (See Crotophaga ani and Blackbird, parrot-billed.) groove-billed (see also Crotophaga sulcirostris). host of Hemaphysalis leporis-palustris.....--....---------- 90 Amteater, host of Amblyomma, cajennensé..-....--- =. s0e22 502 oeetsadecsei.--- 152 Anticoagulin in salivary glands and intestines of Argas miniatus............-- 60 Ant, little black. (See Monomorium minimum.) Ants, enemies of Margaropus annulatus australis. . =o: SS RRR er ets eee eng Aponomma inornata, distribution, zonal, in Monthy honeric Diet eves: FONE ee 22 Apophyses of mandibles of ticks, Gemaitien Dee oc OH Be ee eee ee 16 218 LIFE HISTORY OF NORTH AMERICAN TICKS, Page. Arpas; ‘adaptations of habit) :...2.. 0005552 Ean eee eee ee ee 28 americanus, bibliographic ‘referenee!:. 22209) Ses. oe shee 206, 207 brevipes, distribution, zonal, in North America...................------ 22 in United Statesic...2 a i = ee 45 general: account. Fv feeb 27 ce eo eee 45-46 miniaius; adaptations of habit... 2:4) tle Sh en ok ee 27 sirletiires: «22.27 eee... eee 26 adult, ‘deseriptive 22 ~..2.. 2. 23/5 ee, Ae cee 46 life history <-.-0-. 8.52. Go Re Se ee 58-59 agent in transmission of Spirochxta gallinarum and S. anseri- RUNG POWs 320,200 SR ee ee 46 bibliographic-referenee. 220 Sash Oe oe as i eee ee 208 control ‘aeiticial: 23,2.) tee aus oe 8. 61 Pe URA A2k BLE SP, 26. 60 deserptiver«-a0045 5a SEI de See 46-47 distribution; pecsraphicalixs 2047/0 Ww. 32 in eae 47 zonal in Nofih Americas 4). 25 2. - eee eee 21, 22 CcCOnOIRIO UM PORAMGes . IOUS. ose 8 oe 5 Seiad bo eee eee 60 epg, descriptive: teu yNtaiog Ab he eat oy 5 Lh a See A7 bile: HishOrye sens «cach Po oon 0. eRe 47-53 eggs deposited, iaumiber: porated (shee 33 habiteN ees see ae Aer eS MBN 46 host relationship: 7. seed ah eee Se ee 47 larva, descriptive sii. 25 1 ls 4 46-47 life liistory2..2 0 Ree eee 53-55 MIG.CY ClO Soa dieiceenntn / a, Ae oak ke 59-60 IStORYy ssscead < wtins can ose UE ee oe 48-59 lonige viltiy,,aigaxamotn2.y50 ao SP = oe 45 mating th Sbitss Aree eS ee hr eh cee Sa ee 29-30 nymph deseniptines focssieu oieS Wee. aus ch eo oe 46 lifeshistery. rt eared. (oP eee she ae 55-58 rearing: methods sas22°c Ue hot oa i eee oe 39 BECreHLONS WN er, Sees ee, ae oe 2 ee er 31 persieus, bibliographic references 4. he .0:4 24200... see 25258 207, 208, 212 LOLOTUGL Va NIE ee aorta orci as ro oe Pelee 45, 46 minting habitiss: Jee. ic. etciods OLD 2S eee 30 reflemish eeonoOmMic ii portameeds UA .. Eee Pe 2 ee 45-46 serroneously reported from United States..............------- 45 parasite of fowlscs dss do). Sete hs Bee oo 2 45-46 sp.) bibliographic referente ii 23) ao 2.4 1 ede Boa aes Sees ee eee 207 jalaje,; bibliographic reference... =. 20-2028 WL Pa. SS eee 208 Argaside, development...........-....... J SSID AE A 5 555 he Shee 45 Ass (see also Burro and Donkey). host of Dermacentor -nikensenncs2h4 ack osha Sekacaee eee sa eee 198 occdentalisec 3:23; .2 eR Pe Re 182 Varabilis.csos 2s ER Oe ee 191 VENUSLUS SS SI5, I Ee Ee. « See 166 Ornithodoros Mmegnint. . « «<<. 22.022 ees LS 62 Badger. host.of Ambiyommaamenicaniin: 242-5. see ee Leo ee ee 143 Dermacentor vanabilis- 22h ee BARRERA 191 MENUSIUSES SOL: ee A ee 166 dvodes kingl i.e ado 208s oi. Pe ee ee 82, 83 INDEX. 219 Page. Bartramia longicauda, enemy of ticks......--..-.----------2-eeee eee eee eer eee 43 Batrachians, probable enemies of Hemaphysalis leporis-palustris........-..--- 96 Bear, brown, bose of Dermacentor venusius. ...-.-2.02-6-ss0dhenee-------5---2- 166 Bectic, host.o1 Amblyomma tiberculapus. oa. --na-0ias= bq -25¢22-2---- ee 92-7 = 22 ee 103 Canary, Host Of Argas MiMiGius.- o2c~ cco acme = ee ee 47 Capitulum of ticks, descriptions: -! Ti. . 2.25.52 cee ee ee nae ee eee 16 Capybara, host of Amblyomma cajennense.....-..--------------------+---2--- 152 Carbolic acid and sweet oil against spinose ear tick...............--.--------- 69 Cat, host of Amblyomma OMeriCanwiit...-csensses ce -~ ha peer aie 2 ee ee DY Ape TOV DCMI Uae SE OOS SBS GAAS Gabe aDeeeacaessosssodeL Ss 166 Hemaphaysatis leporis- palustris. wennnce ee ship age aio ates Jeateea a eee 198 larva, descriptive: s..c5-2.Caeke Saeed. aa: < Aye 198 DIPCABISLORES since adeno > j2- 225.4222 sh re cee 186-187 periods in life history, maximum and minimum....-. 70 parumapertus, distribution, zonal, in North America........-..-- 22 marginatus, adaptations of habit......-....-------- 27 adult, deseriphive.. .ctp==5 0: --.2kn58 159 conbrel nahin swe 2s. 5 eee 165 deseriphivpsssit eh weaat-- 2. -s2soee 159 distribution, geographical........... 160-161 zonal, in North America. . 22 economic importance:..4:..-...-.----- 165 cpp. Hesimipmivess:. 2 22... . 21> oaeeee 159 TilG DORON 9s ren cach = 161 eggs deposited, number...........---- 33 host of Hunterellus hookeri.......-.--- 165 yelationship . 2... 2-522 2« 25, 159-160 INDEX. 223 Page Dermacentor parumapertus marginatus, larva, descriptive.............---.----- 159 PC Msenbye. Mee. SS a2 2s: 161-162 Pile C VGke a Seat Metak © sees cet Spake 164-165 nis oree eey eese ee eect 161-164 LochRighioniy eet MNSISe = * 0 nT eS 34 longevity of stages, maximum........- fl males mating with females of Dermacen- tor variabilis and Margaropus annula- GUST eee oe Sadie nine oe a ai ss Se Be 164 molimepghablisMes sas ase eee eee 158 nymph ideseniptive: s2......-525-2225. 159 Mite istory 6 )2o5 222.2 )6008 88 163 periods in life history, maximum and TAIN MP eNe so ke 70 rabbit. (See Dermacentor parumapertus marginatus. ) Venopiis adult deseripiverc: cle ne. Sr VePIleeee: ops. ets 190 HEM LY—c,. SP RES N SU RE ee ors oy 195-196 controlartiiiciale 2. ssateeees See eee ee 197 Leica. eg eee ee eS ay 1 2s ae oe Re 197 eseenp ives so. eee ees, AeA sn lee ert 190-191 distibulion, eeopraphical 2! Ui wee leds... .5e552 2.02% 191 Zonal, ine North Ameri@aes. 22.02 52.52 660 as Economic ptimportance== 5-5 eee eee tee eee eee 197 Sra, doreniplives 2 essa ote e Bee ENE gee. soee 191 [nhieu OURS] O)\ pe hee ae sents Re ok Ae tt Se Re 192-193 eres deppsiteds mumibers ses 5. hoes te SOS. SOS 33 female mating with male Dermacentor parumapertus TEGO UIUGLLLS EE eae ee ED AT eo Mega es REE 164 Has Relations coe tee ee en Re ee 5 ODS 191 laitys, diesem piive aa: 2c 550 Slo eee ote. ae 190-191 Las Muar ye ess Se cy cS ET) Tas Re Se ES 193-194 liter cle were AEs cee See om ae Sey 196-197 mIstanye soca StS. See Ohh. to. 2 191-196 longevity Of stages, maximum esse: 2225.22.82! 71 male mating with female Dermacentor nitens..-.-.-.---- 201 rinyol Whe veg Gk2\l OT Me ae eeepee oR a SS 158 EVAL EMCI tO: . ase eee oe Roe Te eS Se 190 hie; Destomy ot sea aosaee sere os Se ss ek SS 194-195 periods in life history, maximum and minimum......-- 70 REMUS MeL NOUS = ss ice 97 life histomy... 5.92 Mee Jaber ah es Se 100-101 bibliographic:reference 220. 40S 2.23 2.2 ees 208 controls artificialsse.um 22a Seed. ee 102 Haturals|. «22sec os cones eee ane ee ie 102 descriptivessiossurd).4¢. conse eee 28 ae, 7 distribution, peopraphieal..ossit: eek sees 98 zonal, in North America............... 22 SEoNOTICAMpPUrtAnce ..- ..25..)- (ae... Ledeen 101-102 ego» life: history .ict nwa ss 10s 2 De Se 98 host relationship:...2sasesss.2b00 sapere. ¢ sanity 97 larva,.deseriptive:suiveUe Aaa is cae 97 life DishOry:..<:.ccccnal ol Seo See ae 98-99 life. cyclé.... tetas Re i to ae 101 history. so. peak ae.) 2ek.).... Tee 98-101 longevity of stages, maximum.........-..-.-22..25.. 71 molting -habits.<.<.1.22..t¥eesest A ee 89 nymph, descriptive... ns ie.ceice MAN ss aoe 97 life. history:...328s09s FON. Wea See 99-100 parasite. of turkeys. ......22) A495. ae 89 periods in life history, maximum and minimum..... 70 general account... «=< gcir-xajnn2: te, SE ee 89 leachi, agent in transmission of canine piroplasmosis........-. 89, 110 molting habits... 12252) 2 AES FO eee Se 89 leporis-palusiris, adaptations of habit................--------- 27 adult, descriptive: <.2.0.922222 0804: RRS 89 life histotye<2 2AOY PIM «2s. 2. eee 95 control, nabural SAeeowie See a 55. Bees 96 descriptive..So ied etd eed 89 punctata, agent in transmission of bovine piroplasmosis. .....-.- 89 bibliographieireferenees zs se5... ee 208, 211 PHOLuING Mais. Sooo k sa ees be eh. De ee 89 and picking against American dog tick. ........... sie: sos). to ase leeches 197 nar: ficken se emie ae et: Lema. nol aie ble 102 black-legpedatink ste hs Si dtestismels wire. eee. 81 Cayennediek: sen et tes on dies by eete eee 158 Gulhi@oasittick ps tance. eet Geeth AGes 2. SSS 142 hone Stow itielers: eek ae? ese el eae by) sa ee 151 Rocky Mountain spotted-fever tick...........-........ 181 eKEs eT ato eet ei. eatianlertente® eschamsal 44 Hare, host of Hamaphysahs' leporis-palusirias: s225. sss wae) ee sees O.- 90 GRA pike phates BONQUINEUS le. wa Hobe ek Sees wh ee ewe: 103 PeaLeM MA Of TICKS’ 2.2 See Meese res Canoe seubyen inti. Ll. kl S 16 Hawk, accidental host of Amblyomma tuberculatum.........-...------+-+-+-+-+---- 25 host ot Amblyomma huberemmium. 20208. seh. Jase testlact beth eke 2 124 marsh, host:of Humaphysalie chordetlise:. coihaulinza Js 2eseeers 2... 2% 97 Heartwater of sheep, goats, and cattle, transmission by Amblyomma hebreum... 123 Heat in control of Dermacentor parumapertus marginatus.......-.-------------- 165 IPodes iia ts. .nceweescke kee NS ioe s No 3 ee eoas aia iaee 2 88 tickset = ae ass eee ete. peat idieid bo sree: < 41-42 Heloderma suspectum, bibliographic reference.......-.-.22-22:-ss-----+------- 218 Hig host of Amblyomma amenediwimnsssc5553222-5 92 rhieewels led. aude 143, 150 COPCRNMACS «a nace ec sees eee Mee ee eee kat 152 iDeracenitor naraoiliat coos sao bck aos Setters = Lvttanes odes. 191 NETUSTUS Sos sh scenes Se een = SESS MASTERS csc 8.08 166 Orniithodoros megninte... 92.22 eR aS. eae tistadhs 25225: 62 Horse, host of Amblyomma americanums. 222-0: 2k ladon. --.2----+2--..--: 148,148 COJENTENSC == Seis tae SSAA. rife = 22 152, 157 HL DEG CULCUALI tae ee ae ma ais 55 2 te SO ee as = S88 136 IDCPNGCENLON WHERSS A a sok ee ek ka uNenie ¢ 197, 198, 199, 203, 204 oceuieninlis: 22k .2s2 seticss ofeteash em ssissea- 182 DARIO. oe toc tcaie3 cH Samed talon wok 24.cn ssa 191 VENUSTUBL RE sake Ses ata, See oe sok els 166 GOD ED REG DHIOIS. toa ons ssh ae ae eS eA SOE rh Ss. ase 77 Mergeronus annulatysicccts Sessa acce docs sss Bese erah o5 5 e234 112 QUST ALIS2 Se ee AS 2 5 ahs 22 117, 118 Orrathoderas megning. 262 Chae wets Jes eae ~ 2.228 62 hipicephalas San guineuss. f25sccccnk gies . Age os S535 103 Humidity. (See Rainfall and Dryness.) Hunterellus hookeri, bibliographic reference...............-2----------e eee eee ee 214 parasite of Rhipicephalus sanguineus........----- 43, 110-111, 165 Dermacentor parumapertus marginatus......-++- 165 reared from ticks in Portuguese East Africa.......-...-- 110-111 Hyalomma xgyptium, detachment after death of host ................-.------ 72 egos deposited number. Sesttees.243 eed betins. sees 2 32 meline he bliss + Here? Aecos . malladicbih Sheu. 25 impressum, host relationship. ..............-...----+----- 25-26 venustum= Amblyomma vartegatum.......-.-------+++-+--------- 20, 32, 34 228 LIFE HISTORY OF NORTH AMERICAN TICKS. Page. Hylocichla guttata nana, enemy of Dermacentor occidentalis...............-.--- 190 tiCks. occ. ne od a ee ne ee 43 EMypostome of: ticks; description ..235.7.-5.s< StsOL eee tut Sere ne eee 16 Feuana, host ol Amblyomma: dissimile....co--2 Gee See ee ee ee 131 Inflammation caused by Amblyomma americanum.................22+-----++- 150 Dermacentor wccidentalia ne eee 189 Teolation: in: control of fowl tick... 7.5.20. ..-2 Se SR 61 Hodes, adaptations of structure. 0.2... REC. Soe. Se ee eee 28 xqualis, distribution, zonal, in North Amercia............-........--- 22 affinis, wrong determination of Ivodes scapularis..........------.-.--- 77 angustus, distribution, zonal, in North America..................-..-- 22 woodi, distribution, zonal, in North America...............--. 22 arcticus, distribution, zonal, in North America........................ 22 banksi, distribution, zonal, in North America....................-.--- 22 brunneus, distribution, zonal, in North America................-.-.-- 22 California. (See Ixodes californicus.) californicus an important species of genus in United States...........- 76 distribution, zonal, in North America.................-.. 22 mating. habits yeas peer bo icy tl jot ee 30 cookei, distribution, zonal, in North America....!...............-- ar 22 rugosus, distribution, zonal, in North America........-....-...- 22 dentatus, distribution, zonal, in North America...... oie ee te ag 22 diversifossus, distribution, zonal, in North America...............-.--- 22 general:account. oc 5ecea ce eee oe ee too EEE Seer eee 76 hexagonus, distribution, zonal, in North America.................---- 22 mating habitsc..<). ss SOs Pee SEE Se ee 30 kingi, adult, descriptivess So: 22235255 see a BA Ae eee 82 lite. history. soos st sais ras eS eee 87-88 control; naturals oe eee ee ee eee ee eee 88 desereptiwe Jee = 5252s cheered a 3 ee I 82 distabution, geographical S222. .5 2222 a es ee 83 zonal, ine NortheAanerven eee Ae eee ene ee ee 22 economic importance... ....2.....088: Pee we sc oe CEA Ae 88 egg, descriptive:...csjese Sie Ae ee oc eee 82 Life history 2. 3: : 2:4 2ee ea ee Ne a eee fetta)... ... ERSTSG CHESS, OR. ES Se A EE dS Oe me 83 RELRICe DIME SON GHULCUS. «Caz Sire Meet eee Aseey senate 228 2. kk 103 234 LIFE HISTORY OF NORTH AMERICAN TICKS. Page Oryechus vociferus, enemy of ticks. .....-....-A- ies aeianes Bemenaree raises vaeiacne ne ee 16 Rorasites of ticks... -iicsn'ves siases's,s 04s eee SEs aoe ee 43-44 Peccary, host'of: Amblyomma amerteanwMt.-.-» Aseabla’ © «nm wie oc «ame 143 COJENMENEE » 2.0)0 once to SEP aah os <2 se 152 Perodipus richardsont, host of Ixodes bingt 2: <~sdaudaslaceneth s\n ceie aca oneneme 83 Peromyscus maniculatus artemisizx, host of Dermacentor venustus.........--.---- 166 Fetroleum; crude, acainstifowltigke S12 tous... ne onanee jonecet oe che eee 61 Phrynosoma cornutum, experiments: << ocwsisi- asl- okt oe oS a/c e ingeon, hostof Arpass 25. 5367-26 se cein~asett She eaS Doe ee ee oe 46 Pika. (See Ochotona princeps.) Piroplasma bigeminum, transmission by Margaropus annulatus australis....... 122 canis, bibliographic reference. ...........s0000ccedeess- s. 208 causing splenetic fever in bovines, transmission by Meee pea 111 patasites of ticks... 22532. .che Sareea gO PSEe 2 noe 44 parvum, bibliopraphic referencesss etd 2020 eeec é<< See 175, 176 ground (see also Citeilus columbianus). host of Dermacentor venustus...........-.---------- 171, 172, 175, 176 host of Amblyomma americaniwmn..ox « om sae eee Set ee eee 43-44 protozoan. . RE eer ne Rtn ant a RN he = 44 periods in life history Of 6ConODIC Importance iy ALAN. Sey. eee 19 predacshous Enemies... 22.9.2 22225 ea. | OT a a ee 42-43 preserving... 0... 22-4 zeuteheredet-enucubie eet): eee 17-18 protective adaptations of habit. 2224 Jose se aS. ee. Se 28-29 protozoan parasites. .- 22 S..2a- 20 dade ea ees anaes h. 39. eee 44 rearing methods...-....--..-. mnt sWaineeek Qeaephden toed)... ani Re 37-41 reckoning, period, in studiesses vce sad: soe8. . whiso.ceeteeet4 she 36-37 temperature in-studies. 4. ...-.2-:- {.ebttem-cdake Br 35-36 reproductive capacity of species studied. ............-.----+------+---- 33 seasonal history ....00. 22... 2b syoegiee ace ee aa dee cee 34-35 BecretiOns. . J .cakiancss scieeuwets) bobs. : ee beaseee seine See 31 peed, early information on longevity. 2-. .-.: foe Oued: woks.- eee 20 systematic position...:'°. 2.2... 0. [kitten tenes eer) A 2 ee eee ,- 14-17 variation in color and’ size! . ©. /.) JaUees ssheweweetseeB). ee Eee G9 Toad (Bufo marinus), host of Amblyomma dissimile...........--------------- iBu enemy of Margaropus annulatus australis. ........0.-2 cece eee ee eee eee 122 horned. (See Phrynosoma cornutum.) INDEX. 239 Page On HOHG OL LANTDLYONUMNG COICRNENSC = 0.0.0 sie cae os sah vise b nde bes cl duces cincce 152 SR Re ee a Mea ae aN a eid eae uwoce, sel ete bre ale Tortoise, gopher, enemy of Amblyomma tuberculatum.....-.........--------- 130 host of Amblyomma tuberculatum.......---------+------20-- 124 hostiol Amblyomma dissunile. ....522- = 222-2 eee nee ee eel en 132, 133, 134 Sinan ulus paisa: MPAMORCRE CK 62.5). oo. eth eke sen 2 be ess Sd Ses 69 nnomnenvenan ,eneIny Of TICKS: 20.0 2< 25: janes). soe oe o sea escenn edie oe 43 iitcey, nos, OL Hemaphysalis chordeilis.......2---2.++---+--2-+4--s6500 97, 101-102 wild, Host of Amblyomma americanum. 2 -: <= ==. 24-4 00 lo meraisied wai stan =a Puate I. i. TET. ILLUSTRATIONS: PLATES. Sterile jars filled with soil and chinch bugs, showing diseased bugs resulting from a spontaneous outbreak in the jar .....--------..--- Fig. 1.—Chinch bug enveloped in growth of the white fungus (S‘poro- trichum globuliferum). Figs. 2-7.—Dead chinch bugs, showing various degrees of envelopment in the white fungus..........-.--. Various insects killed by the fungus diseases Jsaria sp. and Sporotri- CHT GUO DUNS ETUM ac a cei ores ole ie ie of aie ee oe oe ee eee . Various insects killed by the chinch-bug fungus, Sporotrichum globu- LifeRUM 3.2 Soca Sots Sac aja ho ca oe Ce Seen ne = eee ee ee ee . Fig. 1.—Patch of corn protected by the oiled-straw barrier. Fig. 2.—Cornfield showing corn treated with crude oil......---------- TEXT FIGURES. Fia. 1. Map of Kansas, showing the number of packages of diseased chinch bugs sent out in 1910 by the University of Kansas to the different counties in the anfested arent. 3-25 06. Sts oss oes eis steals soho e one comet ee 2. Map of Kansas, showing all the localities where Sporotrichum was found ano natural antections -c.-%--5 54ers eee asso Se es eee ae eee 3. Diagram illustrating the construction of the dust barrier........------ 4. Diagram illustrating the oiled-ridge type of barrier.......-..--.------ 6 Page. 16 16 20 20 52 15 19 48 50 RESULTS OF THE ARTIFICIAL USE OF THE WHITE-FUNGUS DISEASE IN KANSAS, WITH APPROVED METHODS OF FIGHT- ING CHINCH BUGS. HisroricAL SUMMARY OF CuHINcCH-Bua DIsmEasss. Since Dr. Snow, in his First and Sixth Reports of the Experiment Station of the University of Kansas, has given a somewhat extensive account of the chinch-bug disease prior to 1896, only a brief historical summary is deemed necessary in this bulletin. Three chinch-bug diseases have engaged the attention of entomolo- gists—a bacterial disease and two fuftgous diseases. What was at first supposed to be a bacterial disease was, on further investigation, ascertained to be only a normal condition in healthy bugs, so the two fungous diseases are the only true ones which have received attention. One of the fungous diseases is due to a parasitic fungus, known to science as Hmpusa aphidis, and popularly known as the gray fungus, since it envelops the dead bug in a gray covering; the other is due to another parasitic fungus, known to science as Sporotrichum globu- liferum and commonly known as the white fungus, since it envelops the dead bug in a white cottony mass. The latter is of special interest to us since it is the one which has been under investigation in Kansas. The chinch bug was first noticed in North Carolina in 1783, In the Mississippi Valley it has been known since 1823. Since 1840 it has been under constant observation in [lhnois and other States. It proved such a destructive pest from the first that entomologists have diligently sought for effective remedies by which its depredations could be avoided. The first evidence of disease among chinch bugs was noted by Dr. Henry Shimer at Mount Carroll, Il., in 1865.° According to Dr. Shimer’s notes, this outbreak was first noticed on low creek-bottom land, spreading gradually to the higher localities. The disease attacked both the old and the young, and was at its maximum during the moist, warm weather that followed the cold rains of June and the first part of July of that year. So complete was the destruction of the bugs that he wrote on August 8: Secarcely one in a thousand of the vast hosts of young bugs observed in the middle of June yet remain alive, but plenty of dead ones may be seen every- «Vitch’s Noxious Insects of New York, 1865. > Dr. Forbes’s Insect Life, vol. 1, No. 8, p. 259. ¢ See Bibliography, p. 54. 8 THE WHITE-FUNGUS DISEASE IN KANSAS. where lying on the ground, covered with the common mold of decomposing ani- mal matter, and nothing else, even when examined by the microscope. Even of those that migrated to the cornfields a few weeks ago in such numbers as to cover the lower half of the cornstalks, very few are to be found remaining alive; but the ground around the base of the corn hills is almost literally coy- ered with their moldering, decomposing bodies. This is a matter of so common occurrence as to be observed and often spoken of by the farmers. They are dead everywhere, not lying on the ground alone, but sticking to the blades and stalks of corn in great numbers, in all stages of development. Entomologists were slow to accept Dr. Shimer’s theory of an epidemic disease. Walsh and Riley ridiculed the idea, and Le Baron six years later declared that he knew of no predaceous parasitic enemies of the chinch bug. Later observations, however, confirmed the accuracy of Dr. Shimer’s observations. Evidence of disease among chinch bugs was not again reported until 1882, when Dr. S. A. Forbes, of Ilinois,!* and Prof. Popenoe, of Kansas,' both reported localities in their respective States in which the bugs were dying with a fungus disease which embedded the dead bugs in a growth of white mold. In August of the same year Dr. Forbes discovered what he thought was a bacterial disease due to a bacillus which he found in great num- bers in the alimentary canal of dead bugs; 1° but after a thorough in- vestigation, which extended through several years, he ascertained that the presence of the bacillus was a normal condition in the alimentary canal of healthful chinch bugs, and the theory of a bacterial disease was abandoned. The fungus disease noted by Dr. Forbes and Prof. Popenoe was what is commonly known as the gray fungus, Hmpusa aphidis. What fungus was responsible for the disease among the bugs reported by Dr. Shimer can not be ascertained. The white fungus had not yet been detected. This fungus was first observed by Dr. Forbes in Clinton County, Il., July 7, 1887, and again on August 7, 1888.°° *4 For more than a year this fungus affection was not found among chinch bugs, although a close watch was kept for it, but August 7, 1888, it was seen at Flora, in Clay County, fastening dead bugs to leaves of corn. Almost simultaneously it was reported from Minnesota,*? Iowa,’ Ohio, and Kansas.*° It is worthy of note that no evidence of disease among chinch bugs was noted for about 80 years after the chinch bug became known as a serious pest, and it was 100 years after its first appearance that the white fungus was definitely recognized. It is also all the more re- markable in view of the prevalence of the disease over such a wide area at this time and during the years following. If these diseases were present among the bugs from the first, it seems strange that they were not detected earlier, and if they were in the process of in- troduction it seems strange that almost simultaneously they should be so plentiful in so many different, widely separated localities. It HISTORICAL SUMMARY: OF DISEASES. 9 is probable that they were present from the first, but because of the fact that they are so dependent upon the abundance of their host and upon favorable weather conditions they are not conspicuous except at intervals when conditions are just right. In the years immediately following the discovery of the white fungus much attention was given to the investigation of chinch-bug diseases. Dr. Lugger, of Minnesota, was the first to attempt to disseminate the disease by the distribution of diseased bugs. In October, 1888, he sent diseased bugs to various localities, and the experiment was apparently successful, as the bugs in these localities were found to be dying with the disease a little later. But the disease spread so rapidly that Dr. Lugger was led to suspect very strongly that the spores of the disease were already in these localities and that he had only reintroduced them, the spread of the disease being due to the spores that were already there rather than to the spores which he introduced.*? * Dr. Snow’s observations and experiments in Kansas began in 1888 and extended through the season of 1896. In 1888 the chinch bugs disappeared from some of the eastern counties of the State during the months of May and June, and Dr. Snow expressed the belief that they were carried off by an epidemic.*® Experimenting with the gray fungus, /’mpusa aphidis, he found that the disease could be communicated from diseased bugs to healthy ones by confining healthy bugs with the diseased ones. He also sent some diseased bugs 1o farmers and to agricultural experiment stations in Nebraska, Iowa, Missouri, Minnesota, Michigan, Indiana, Illinois, and Kentucky. The reports received from those who received the diseased bugs were very encouraging. In 1890 chinch bugs in Kansas were very scarce, having been very generally exterminated in 1889. In 1891 the legislature established an experiment station at the University of Kansas “to propagate the contagion, or infection, that is supposed to be destructive to chinch bugs, and furnish the same to farmers free of charge, under the direction of the chancellor, F. H. Snow.” During this period between 40,000 and 50,000 packages of the fungus were sent out to farmers, and extensive experiments were carried on in the laboratory and some in the field; the life history of the white fungus was worked out, and the best means of propagating it in large quantities ascertained. Observers were sent out from the station at various times to make observations in the field. The reports of these observers in 1891 and 1892 were very favorable, but in succeeding years the results of the observations were less favorable and brought to light the probability that the fungus was widely distributed naturally, since it seemed to be the rule rather than the 10 THE WHITE-FUNGUS DISEASE IN KANSAS. exception that the fungus was working as effectively in fields where none had been introduced as in fields where it had been artificially distributed. The fungus was found in every locality where the inspectors made observations. In commenting on this fact, Dr. Snow gad :*° Whether this widely extended natural presence of the Sporotrichum was the result of the general introduction of the infection throughout the State, in 1894, from the laboratory of this station it would not be possible with certainty either to affirm or deny. A full account of Dr. Snow’s work will be found in his six reports of the experiment station of the University of Kansas for the years 1891, 1892, 1893, 1894, 1895, and 1896. The following is taken from his last report: ’ RESULTS OF EXPERIMENTS FOR 10 years, 1888—1897.*" 1. Chinch bugs in any of their stages of development scarcely run the slightest risk of death on account of heavy rains, even when these are of long duration, They are inconsiderably affected by extremes of heat and cold. 2. We know of no contagious bacterial disease of the chinch bug. 3. There are two parasitic, contagious, fungoid diseases that kill chinch bugs, namely, Sporoirichum globuliferum (“‘white fungus”) and Hmpusa aphidis (“gray fungus”). 4. These two diseases show their greatest virulence where the ground is damp and shaded from the direct rays of the sun and the air is humid. 5. We do not know to what extent the spores of these diseases are normally present in any given region. When they are present, whether naturally or artificially introduced, and the weather conditions are as given above, and the bugs are massed together, an outbreak of the diseases will occur. The number of chinch bugs killed in any field is approximately proportionate to the number of bugs in the field. ; 6. Sporotrichum can be artificially communicated to healthy chinch bugs. (a) It attacks bugs of all ages, but the older the bug the more easily does iu succumb. (0b) Bugs of any age that have been weakened from any cause, or injured, fall more easy victims to the disease than do those individuals that are in perfect condition. (c) The adults of the second brood, which, in the ordinary course of events, winter over and lay the eggs for the brood of the succeeding spring, are much more successful in resisting the disease than are the adults of the first brood. (d) The fungus is not active in winter, and, though it be present with the bugs in their winter quarters, they do not die of it, even though the winter be as mild and humid as was that of 189596. The chinch bug seemed to have been almost exterminated in 1896 and there has not been any widespread outbreak since until the last two years, and hence little opportunity to investigate the practical value of the use of Sporo- trichum until this year. Many requests for the fungus were received at the university last year, but no provision was made by the university to supply it until this year, WORK IN OTHER STATES. The method of combating chinch bugs by the artificial distribution of infection has been extensively used in other States, but in most cases the practice has been abandoned. HISTORICAL SUMMARY OF DISEASES. rT Dr. Lugger, who first attempted to disseminate the disease by means of distributing diseased bugs in 1888, adopted the plan again in 1895. In the First Annual Report of the State Entomologist of the State Experiment Station of Minnesota for the year 1895, he says: Judging from the large number of letters, the writers were well pleased with the results of spreading spores among chinch bugs. * * * Of course it would be folly to claim that the disease was always spread by the introduction of such spores, and it is also possible that it would appear simply because the climatie conditions were in its favor. Whatever may be the reasons for its appearance, so many farmers believe in the effectiveness of introducing spores causing the disease that the State can well afford to continue this work. However, the practice has been abandoned in Minnesota. Prof. F. L. Washburn, State entomologist, in Bulletin No. 77, Agricultural Experiment Station, 1902, says: We do not know of any profitable means of killing the chinch bugs in the grain at present. In this connection we will say that the sending out of dis- eased chinch bugs has been abandoned, it having been found that the results were not sufficiently practical. Dr. S. A. Forbes, who first definitely recognized the white fungus in 1887, began an extensive series of experiments with this and also the gray fungus, which lasted till 1896. The results of his investi- gations were not such as to lead him to recommend the use of the fungous diseases as a means of combating chinch bugs, although he was not ready to declare the method a failure. By isolating bugs sent in by farmers, he found that the disease developed among a large percentage of them without their being inoculated, and thus was led to conclude that the disease was very generally distributed naturally. In a series of field experiments he found that the disease was as prevalent in fields in which the fungus had not been introduced as in the fields in which it had been thoroughly distributed. Accounts of these experiments are recorded in the Sixteenth, Seventeenth, Kighteenth, Nineteenth, and Twentieth Reports of the State Ento- mologists of Illinois, 1888-1896. In the Twentieth Report he says: Whether the fungi of contagious diseases can be artificially made use of to hasten or intensify the serviceable effect of favorable weather with a frequency or to an extent to make this procedure economically worth while, I am not yet prepared to say. The methods of distributing these fungi in the fields have hitherto been too crude to make their substantial failure conclusive as to the whole subject. It now seems quite clear that they can be at the best only used aS a secondary to other measures, especially the midsummer measures described in the third article of this report. If applicable at all, however, they can be brought to bear at a point now entirely defenseless, and it seems the duty of American economic entomologists to spare no pains to investigate to a final and indisputable conclusion which promises so much as a remote possi- bility that the chinch bug may be attacked even to occasional advantage after it has settled itself in fields of small grain. i ie THE WHITE-FUNGUS DISEASE IN KANSAS. In Nebraska the fungus was used extensively in 1893, 1894, and 1901, but in the outbreaks of 1909 and 1910 the fungus was not recom- mended. To those asking for the fungus a cireular was sent, which says in part: It seems that the usefulness of this fungus disease as a method of destroy- ing chinch bugs has been greatly overestimated by the farmers, since the ex- periments with it show that it spreads only when the weather conditions are just right—that is, when the temperature is somewhere between 70° and 80° F., and the air is very humid, and when bugs are massed in sufticient numbers that they come in contact with each other. When such conditions exist, the disease spreads rapidly and destroys the bugs very effectively, but under other conditions, especially in dry weather, the disease is quite ineffective. It is be- cause of this extreme unreliability of the chinch-bug fungus disease, and its failure to spread when most sorely needed, that we have come to regard it as more of a detriment than a benefit in many cases, since it causes the farmer to place confidence in an unsafe measure to the neglect of more practical, though also more laborious, means of control. The fungus was also used in Missouri, but has been discarded. Prof. J. M. Stedman ® says: A great many people send in to this office in the spring of the year for the chinch-bug disease, with the idea of scattering this disease about the fields of wheat and killing the chinch bugs infesting them. It is a fact that under cer- tain climatic conditions this chinch-bug disease * * * will kill a great number of chinch bugs. But from seven years’ experience with this disease in the wheat fields throughout the State of Missouri I am firmly convinced that the artificial use of this disease by the farmers of Missouri does very little, if any, good. * * * In the first place the chinch-bug disease is a natural one, found in nature, and is not an artificial one. * * * * * & Tf the chinch bugs are in large numbers and the weather is hot and very moist, these spores will germinate on the bugs, and the fungus plant will kill them in great numbers. But if the weather is hot and dry, or too cool, although it may be moist enough, then the spores will not germinate, and no agriculturist has the power to bring about the proper conditions in his wheat or cornfield that will enable them to germinate. * * * * * + JT wish to say that it is very doubtful whether there is a wheat field or a cornfield in Missouri that does not naturally contain spores of this disease. I have been impressed with this fact every summer, because almost invariably, when the person applying for the chinch-bug disease sends to this office living ehinch bugs that have been placed, as they should be, in a tin box containing no dirt, but some green vegetable matter, as for instance, pieces of green corn, wheat, or grass, and the box closed up as it should be, perfectly tight, thereby generating moisture in the box from these green vegetables, that by the time these bugs reach me the box contains more diseased fungus-covered bugs than we return; thus showing that the spores were already there in his field. * %* * Knowing these facts, I can do no other than to conscientiously advise the farmers of Missouri not to trouble themselves with obtaining and scattering this disease about their fields, but to rely entirely, as they will ultimately have to do, upon nature to bring about the proper climatic conditions for the de- velopment of this disease in their fields. “Bulletin No. 51, Agr. Exp. Sta., University of Missouri, July, 1902. HISTORICAL SUMMARY OF DISEASES. 13 Prof. F. M. Webster was one of the first to interest himself in the investigation of the fungus. Asa special agent of the United States Department of Agriculture, located at La Fayette, Ind., he conducted some experiments which showed that moisture and a large number of bugs are essential factors in the successful propagation of the dis- ease.** Later, as State entomologist of Ohio (now connected with the U. S. Bureau of Entomology), he experimented with the fungus in Ohio in 1895 and 1896. As 1895 was a dry season the fungus proved ineffective; but in 1896 the weather conditions were favorable, and Prof. Webster states: °° °° I have always held to the opinion that the parasitic fungus Sporotrichum globuliferum could only be used in a manner to effect relief to the farmers dur- ing wet seasons and where there was a superabundance of host insects * * ¥*, This year (1896) I can say with all conditions favorable, Sporotrichum globuli- ferum has done all that Dr. Snow or any other entomologist claims for it, but under conditions as adverse as these have been favorable the results will prove quite the reverse. It would seem that Prof. Webster’s subsequent observations have not materially changed his views; for he states in November, 1909: ¢ As the fungus has many other host insects, it is probably present to a greater or less degree throughout the country every year. There is no doubt that during wet weather considerable benefit may be derived from the artificial cultivation and application of this fungus, but its efficiency is very dependent upon this meteorological condition, and, as has already been shown, chinch bugs develop in greater abundance in dry seasons. It will thus be seen that only during unusual seasons, that is to say, seasons that have been very dry while the chinch bugs were hatching from the egg, but wet afterwards, can satis- factory results be expected from this measure. Thus it appears that the use of the fungus has not come into gen- eral use as a means of combating the chinch bug. Its use has been abandoned in nearly every State that has given it a good trial. Only three States sent out fungus during that season—Oklahoma, Ohio, and Kansas. Dr. Gossard, of Ohio, questions very seriously the wisdom of sending out the fungus and our investigations in Kansas this season, as the report shows, have made it certain that in Kansas at least the artificial distribution of the fungus is unnecessary. Its failure to come into general use may be ascribed to the following reasons: 1. The disease proves effective only during unusually wet seasons and when the bugs are very plentiful. 2. The disease is quite generally present in the field naturally. 3. Dependence on the fungus leads farmers to neglect other more practical means of control. * Circular No. 113, Bur. Ent., U. S. Dept. Agr., 1909. 14 THE WHITE-FUNGUS DISEASE IN KANSAS. OuruInE oF WorK AGAINST THE CuHiIncH Bua CARRIED ON IN KANSAS DURING 1910. Owing to the presence of chinch bugs in destructive numbers over a considerable portion of the State in 1909, many requests were re- ceived for diseased bugs. The demands ‘became so insistent that the regents of the University of Kansas made provisions for supplying the fungus to all applicants during the season of 1910. Following the methods used by the late Dr. Snow, a package of diseased bugs, » accompanied by the necessary literature, was mailed to each appli- cant. The mailing list was primarily for residents of Kansas, but a number of farmers in Oklahoma were supplied with the fungus. The literature consisted principally of a four-page folder, which contained, besides information for the use of the fungus, other infor- mation which was designed to enable the farmers to make intelligent observations in their own fields and to avail themselves of other methods of fighting chinch bugs, It was understood that many authorities do not advocate the arti- ficial use of Sporotrichum; still, in the absence of conclusive evidence to prove its impracticability, the recommendations of Dr. Snow in his last report were followed, with the hope that in the face of a threatened chinch-bug epidemic some good might result. At the same time, however, provision was made for an investiga- tion in order to determine definitely whether or not artificial infec- tion accomplishes results sufficient to justify the labor and expense involved. Work began early in 1910, some months before any infection was sent out. It was necessary to determine early which portions of the State were suited for carrying on experiments, judging from the number of bugs, and the extent of the distribution of the fungus naturally in the soil. Data as to the distribution of the fungus were regarded as more nearly conclusive if obtained before artificial dis- tribution began. No Sporotrichum had been distributed in Kansas since Dr. Snow distributed it from 1891 to 1896. Dr. Snow’s reports show that the fungus was very generally present in the fields in 1895 and 1896, and on that account results derived from its artificial distribution were of doubtful benefit. This was thought to be a very favorable time for determining if the fungus had meanwhile maintained itself in the fields. Whether or not the fungus found in the soil at that time was the result of that sown by Dr. Snow years ago is, however, not pertinent to the problem, since the problem concerns itself with a plan of action for the present and future. OUTLINE OF WORK AGAINST CHINCH BUG. 15 In comparing the First Annual Report of Dr. Snow for 1891 with the last one for 1896, we find statements which would lead us to believe that the artificial distribution of the disease had at least the hinch bugs sent out in 1910 by the University of (Original. ) sted area. Kansas to the different counties in the infe Fic. 1.—Map of Kansas showing the number of packages of diseased ec effect of increasing the amount of Sporotrichum, even if we doubted its first introduction into Kansas in the nineties. In the report of 1891 we read: It must be remembered that these contagious diseases of the chinch bug are naturally present in certain ortions of the Mississippi basin during every 10944°—Bull. 107—11 2 16 THE WHITE-FUNGUS DISEASE IN KANSAS. year, and become epidemic over large portions of this area in occasional years. The object of my experiments has been to artifically introduce the disease at times when they are not naturally raging in the fields. It was found in 1891 that there was no evidence of a natural existence of the three diseases in any part of the State of Kansas. This statement is abundantly substantiated by the detailed report of my field agent. Mr. Hickey, and by the reports of many farmers. In his final report Dr. Snow makes this comment: While no such general epidemic of Sporotrichum was noted in this year (1896) as occurred in 1895, yet the disease seemed present in those parts of the State visited, wherever favorable conditions existed, and in the fields, whether artificially infected or not. It was therefore doubtless true that in the later years of Dr. Snow’s campaign many spontaneous outbreaks occurred, and that conditions were perhaps not widely different from what they are to-day. Owing to a lack of scientific data, however, there is room for doubt as to the absence of Sporotrichum from Kansas soil prior to the recorded observations in 1891. The investigations summarized in this paper had chiefly to do with the following problems: 1. Extent to which the white fungus disease of the chinch bug is naturally present in Kansas soil. 2. Practicability of artificial infection of fields in which the fungus disease is found to be naturally present. 3. Practicability of artificial infection of fields in which the fungus disease is shown to be scarce, or at least ineffective. 4, Experiments with barriers and insecticides. Among other matters considered were (1) laboratory methods of propagating Sporotrichum; (2) artificial inoculation of chinch bugs with spores. NATURAL DISTRIBUTION OF SPOROTRICHUM IN KANSAS. In any investigation to determine the efficacy of artificial infec- tion of a field with a parasitic fungus, the presence or absence of the fungus is one of the first points to be determined. If its ab- sence be proved, a widespread persistent application of the infec- tion might result in a considerable mortality of bugs, provided, of course, they are numerous enough to spread the contagion among themselves; but if the presence of the fungus is shown to be general, the problem resolves itself into that of attempting to improve natural conditions by artificial ones. Theoretically, at least, such a thing would be possible, but its practicability must be determined by actual experiment under a variety of conditions. It would have to be shown that enough bugs, beyond what naturally would have died, succumbed to the artificially sown fungus to make the effort worth while. Bul. 107, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE |. STERILE JARS FILLED WITH SOIL AND CHINCH BuGS, SHOWING DISEASED BUGS RESULTING FROM A SPONTANEOUS OUTBREAK IN THE JAR. (ORIGINAL.) The white spots in the jars are fungus-covered bugs. Bul. 107, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE II. Fic. 1.—CHINCH BUG ENVELOPED IN GROWTH OF THE WHITE FUNGUS SPOROTRICHUM GLOBULIFERUM. FROM PHOTOMICROGRAPH ENLARGED X 22. (ORIGINAL.) Fics. 2-7.—DEAD CHINCH BuGs, SHOWING VARIOUS DEGREES OF EN- VELOPMENT IN THE WHITE FUNGUS. FROM PHOTOGRAPHS ENLARGED X 7. (ORIGINAL.) NATURAL PRESENCE DURING HIBERNATION. 17 A spontaneous outbreak of the fungus in a field into which no fungus had been introduced would imply its natural presence there; and, conversely, its natural presence there would imply that a spontaneous outbreak would be possible, if given proper conditions. Hence it was determined te visit representative counties distributed through the infested area, and by examination of fields taken at random ascertain to what extent Sporotrichum is present in Kansas soil. NatTurRAL PRESENCE OF SPOROTRICHUM AMONG CHINCH BUGS DURING HIBERNATION. As conditions for the development of the chinch-bug disease were not favorable while the bugs were in hibernation, partly because of the cold or cool dry weather that prevailed and partly because of the resistant state of the insects, it was necessary to collect them and bring them into warm, moist surroundings, where, with increased activity, without food, their vitality would be diminished sufficiently for them to succumb to the attack of the disease. The type of collecting jar adopted was an 8-ounce square bottle with wide mouth and metal screw top lined with cork. This was light in weight and packed well in a carrying case. Before taking a lot of bottles from the laboratory they were thoroughly sterilized in an autoclave. The tops were left loose during sterilization and then screwed down tightly upon removal, while hot, from the sterilizer. After placing a number of bugs and a small quantity of earth in a bottle, by the use of sterilized tools, the lid was screwed down tightly and not removed until the bugs were dead, unless the soil in the bottle was too dry, in which case a little water was added, either from a near-by source in the field or else in the laboratory. If in the laboratory, precautions were taken against exposing the contents of the bottles to contamination. The tops were loosened and lifted on one side only, and then just enough to permit the entrance of a sterile pipette, filled with sterile water. By working expeditiously no more danger of contamination from the air resulted than in making trans- fers from one culture medium to another. The favorite places for hibernation on the part of the chinch bugs, apparently, were the stools of the prairie grass, Andropogon sco- parius. The grass was uprooted and some of the bugs placed in bottles by the use of sterile lifters. Several bottles of bugs, together with a portion of the surrounding earth, were collected in at least one locality in each county visited. It was desired to ascertain if a spontaneous outbreak of the fungus could be obtained among the incarcerated bugs. Since, under the natural conditions to which the bugs were subjected in the bottles, 18 THE WHITE-FUNGUS DISEASE IN KANSAS. there was a possibility that the proper conditions might not be secured in some of them for the fungus to develop, the uncer- tainty was eliminated by having a number of bottles from each locality. Sporotrichum appeared in most of the bottles (see Pl. I), though its occurrence in but one of a series was sufficient to establish the certainty of its presence in the locality from which the collection had come. In some of the bottles no Sporotrichum developed. This was generally due to an excess of moisture which caused bugs to die before the Sporotrichum had time to make its presence manifest. The chinch bugs in the bottles generally showed remarkable powers of endurance, as they were without food yet in warm sur- roundings. Some were found still crawling more than two months after collection and long after observations were taken. Some con- tinued to live for this length of time with the Sporotrichum present and projecting conspicuously from dead bugs (see Pl. II) over which they frequently crawled. . . Thirty-two counties in the infested area of Kansas were definitely shown to contain the white-fungus disease among the chinch bugs before egress from their winter quarters, during the latter part of March. The first package of diseased bugs was sent out April 7 by the Kan- sas State Agricultural College at Manhattan. Five days later the University began its distribution of diseased bugs. It is therefore evident that Sporotrichum was present naturally in the localities examined and only needed the proper climatic conditions to break out spontaneously in the fields. NATURAL PRESENCE OF SPOROTRICHUM IN Wueat Fretps AND Corn- FIELDS DURING THE SPRING AND SUMMER OF 1910. Spontaneous outbreaks.—The chinch bugs left their winter quar- ters the last week in March, but owing to the dryness and coolness of April, no diseased bugs were found in the fields until late in the month. In the meantime the collecting of bugs and testing for the presence of the fungus continued. Later, when fungus-covered bugs were present in the fields, they were considered as direct evidence of its natural distribution, provided artificial distribution had not been resorted to. Observations on the presence of Sporotrichum among chinch bugs in grain fields occupied the months of April, May, and June. During this time 27 additional counties were shown to contain the fungus. Summing up the work on the natural distribution of the fungus disease, it was found that 59 counties, which include most of the infested area of Kansas, showed evidence of its presence. Six coun- ties, four of which were on the western edge of chinch-bug distribu- NATURAL PRESENCE IN FIELDS. ‘ 19 tion, where excessive drought or else scarcity of bugs constituted the conditions met with, failed to show presence of Sporotrichum. Two counties, on the northeastern border, because of great scarcity of bugs, also failed to show signs of fungus. A few counties situated among (Original. ) Fic. 2.—Map of Kansas, showing all the localities where Sporotrichum was found as a natural infection. - tet bs ni others in which Sporotrichum was observed probably contained it, but, as they were not visited, no direct evidence was obtained. Granting its absence in such localities in 1910, however, it would be but a short time, owing to migration of the chinch bugs, before 20 THE WHITE-FUNGUS DISEASE IN KANSAS. spores from the adjacent counties would be carried over into every field where they might alight. As will later be shown, Sporotrichum is not dependent on chinch bugs for hosts, but may live on other insects. There is hardly any question as to the presence of the fungus in the soil generally. Maintenance of Sporotrichum in the soil—From the ease with which Sporotrichum is cultivated in the laboratory at room tem- perature with dead organic substances as culture media, it is possible that it propagates itself, at times, saprophytically in the soil. It is not dependent, however, either on dead organic matter or on living chinch bugs, but may live as a parasite on other insects, some of which are present in Kansas as permanent fauna. Various writers from widely separated localities have reported Sporotrichum on insects other than chinch bugs. While making no attempt to search for the fungus on other than chinch bugs, the writers noticed insects from time to time displaying the characteristic Sporotrichum growth. A list of them is given below. INSECTS UPON WHICH SPOROTRICHUM HAS BEEN Founp. Three common snout beetles, 7richobaris texana, Conotrachelus erinaceus, and Anthonomus fulvus (Pl. IT, figs. 1, 2, and 3) ; a com- mon flea-beetle, Disonycha triangularis (Pl. IIT, fig. 4;) a very com- mon lady-beetle, Wippodamia convergens (Pl. III, fig. 5); a minute beetle of the genus Olibrus (Pl. III, fig. 6); and three true bugs belonging to the same order (Hemiptera) as the chinch bug, one arather rare insect, belonging to the family Phymatide, the species un- determined, and the other two common forms, J/icrotoma carbonaria and Coriscus ferus (Pl. IV, figs. 1, 2, and 3), and two unidentified larvee (Pl. IV, figs. 5 and 6), and many common pentatomids. NATURAL DISTRIBUTION OF SPOROTRICHUM IN THE SOIL AND ITS RELA- TION TO ARTIFICIAL INFECTION. The general distribution of Sporotrichum naturally in the soil might affect the artificial use of the fungus in one of two ways—by rendering it unnecessary, or by making it more effective. In the former instance a spontaneous outbreak would occur, which, if con- ditions were right, would be of such magnitude that, whatever man might do in the way of artificially distributing fungus spores, noth- ing appreciable would be added to the results; or, given unfavorable conditions with a slight spontaneous outbreak, or none at all, artificial infection would not measurably spread the disease. In the second instance when there is already a spontaneous outbreak of considerable size, artificial infection might increase this to an epidemic that would end in a high percentage of mortality among the bugs. Other Bul. 107, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE III. VARIOUS INSECTS KILLED BY FUNGUS DISEASES. No. 2 IS ISARIA SP., THE OTHERS SPOROTRICHUM. (ORIGINAL. ) Fig. 1.—Trichobaris texana. Fig. 4.—Disonycha triangularis. Fig. 2.—Conotrachelus erinaceus. Fig. 5.—Hippodamia convergens. Fig. 3.—Anthonomus fulvus. Fig. 6.—Olibrus sp. Bul. 107, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IV, VARIOUS INSECTS KILLED BY THE CHINCH-BuUG FUNGUS, SPOROTRICHUM GLOBULIFERUM. (ORIGINAL.) Fig. 1.—Macrocephalus sp. Fig. 3.—Coriscus ferus. Fig. 2.—Microtoma atrata. Fig. 4.—¢ oriscus ferus, VY mph, Figs. 5 and 6.—Unidentified larve. INFECTION EXPERIMENTS IN LABORATORY. 21 fields not artifically treated would then show merely a spontaneous outbreak with a lower percentage of mortality. The settlement of these problems was merely a matter of experiment under conditions that would cover possibilities mentioned above. As soon as spring opened and weather permitted, field investigations began; the pur- pose being to ascertain whether artificial treatment of a field infested by chinch bugs would prove profitable. One phase of the matter as described earlier in this paper had already been settled; the Sporotrichum disease was widespread naturally over the infested sec- tion of the State. It remained to be shown, first, whether sowing fungus spores in an already infested field would increase the epidemic, and, second, in a field showing but little evidence of Sporotrichum whether such a treatment would start an epidemic, otherwise im- probable. ArtTIFIcIAL INFECTION EXPERIMENTS WITH SPOROTRICHUM IN THE LABORATORY. Preparatory to the field work it was found necessary to experiment with the fungus in the laboratory in order to determine the best method of propagation and the effect of the artificially grown cultures on chinch bugs. Quite definite results had already been obtained by Stevens, Barber, and Forbes, and advantage was taken of their conclusions, but at the same time it was thought best to experiment anew and adopt the methods best adapted to the experiments in hand. Sporotrichum was first isolated from transfers made into nutrient agar from a chinch bug dead of the disease. Once obtained pure, there was no difficulty in propagating it on artificial media. For field infection large quantities were needed, so that infection boxes which were designated for infecting bugs for distribution to farmers proved inadequate. The 10 c. m. petri dish used in bacteriological investigation was selected as the vessel in which to place the nutrient medium for growing the Sporotrichum. The fun- gus will grow on ordinary beef broth agar, but this was not found so useful as a combination of potato extract and corn meal. Virulence of artificial cultures—It was realized early in the in- vestigation that the value of any work along lines of field infection depended upon a knowledge of the virulence of artificial cultures, since these were to be employed to a large extent. It was found that so much more fungus could be produced artificially with such cer- tainty that diseased bugs, while used, were not depended on for the major part of the work. To test the virulence of the fungus, experi- ments were conducted at various times by artificially infecting chinch bugs with culture fungus (that grown on the potato-cornmeal medium) and then comparing results with others not so infected or infected by the use of diseased bugs. 22 THE WHITE-FUNGUS DISEASE IN KANSAS. Experiment 1—This experiment was started April 29, the bugs being collected at Colony, a locality which showed an extraordinarily small amount of Sporotrichum in the soil when compared with other localities (except Garnett, in the same county). By selecting bugs from Colony it was hoped to avoid, as far as possible, the presence of spores on the bugs or in the soil before the experiment began. The insects were collected in five sterile bottles, with an approximately equal quantity in each. One bottle was infected with spores from an artificially grown culture. The other four bottles were not opened after they were sealed in the field. By May 13 three diseased bugs were noted in the infected bottle. Four days later all the bugs in the bottle were dead and about half of them were covered with a visible and typical growth of Sporotrichum. The bugs were dead in the four check bottles, but no fungus developed. Experiment 2.—This experiment was designed to reach the same as the previous one, but by a different method. It began May 7. Six screw-capped bottles, each containing 100 grams of earth, were sterilized in an autoclave. Bugs direct from the field and not arti- ficially infected were placed in three of them. To the other three bottles were added bugs, in approximately equal numbers, which had been allowed to crawl for two hours over a moist Sporotrichum culture. Final observations were taken 10 days later. In the uninfected bottles no fungus developed... Two of the other three contained two and eight diseased bugs, respectively. No fungus appeared on the third. The short period of 10 days duration to an extent eliminated deaths by Sporotrichum resulting from extreme weakness due to pro- longed incarceration and starvation. Experiment 3.—This experiment was designed to compare the rela- tive effectiveness of fungus grown on a culture medium and that arising naturally on chinch bugs. Thirty screw-capped bottles were prepared with 100 grams of soil in each bottle, then the whole was sterilized in the autoclave. About 18 chinch bugs were placed in each bottle. A sterile pair of forceps was used to transfer the bugs, and unsterilized field earth was avoided as far as possible. Bottles 1 to 10 were checks, No. 10 having no infected material added. Bot- tle 11 contained bugs which had been shaken up in a small box with three fungus-covered bugs which were finally added to the bottle before it was sealed. Bottle 12 was prepared in the same manner. Bottles 13-17 contained bugs that had been shaken up with a lot of crushed diseased bugs. Bottles 18-20 contained bugs that had been shaken up with soil which had previously been made infectious by rubbing up diseased bugs in it. Bottles 21-30 contained bugs that had been allowed to crawl over a mass of Sporotrichum grown on culture medium, INFECTION EXPERIMENTS IN LABORATORY. 93 All bugs were collected at Cherryvale, a locality that showed an abundance of Sporotrichum in the soil; hence the positive results in the check bottles. The experiment began May 7, and by May 24 all the bugs in all the bottles were dead. The results are tabulated below: BOTTLES 1 TO 10. OURO NOS mec eee ae jaece ene see Mesa sce aememoaae ales 1 2| a s[sfo[z|s| or Date Number of diseased bugs. WEN? U0) 3eae Genpide das GS ae PiSe AOS pAe Any COs ORE U GSS Aorinc RESP Aace Aaee AEes cS) Mace ACE APE Mase mere Serie (sare MBAS? Sen ccccetcce snc aees onder ccna ocee catice naciclnemecns ae Seas | peters oven | ee ois heimtatal ere ccs| ome omietelecies IMB IGS oS icc doe sos sees ec tiecte Ae his ccisto ec cedalstnsaee crs Uh eee Uy eel nee eee eee rise Meee MAY 24l in Aeyo ame Senet ame a pees eaeseciicce nine moaaw stance SY 70) a tlie2 1 Total number of diseased bugs, 13. BOTTLES 11 TO 20. BOLHOMN OMe scien solemn bans ae teicisios sejsitccre sis cect ewanscres 11 | 12'} 18 | 14] 15 | 16 | 17 | 18 | 19 | 20 Date. Number of diseased bugs. PML OMsce re yee ute OM herria. eee L erably Sew Uae | Oe (esis |e el rd gee Des 2 1 IES AGE BU Se cee Se Me Oe aa eb ae en 2 eee ioe a 1 1 1 2| 2 1 PAN Peed | 2 Maya l Ghee MMe SNE LIEN EAS Sha hae SC MAL are UNE | OO ae a ll ait ea pees 4 IE gp 8 AR A Se ene i ae ee eee ed eee en ee ee es aU TAT aC] ee Sa A lal 4 Total number of diseased bugs, 53. BOTTLES 21 TO 30. ES GULIOIN OM ee eerie cates etme otc Cena oe neh seeeinee 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 Date. Number of diseased bugs. Mav aL beers Se eee er carta ee as een See LES. 2g Smeal se te ede MI a Uline aR sell socal is ae MinvitOr ee Seoge res Pee tree ey Pabeyhe e548 sr BN Vd ata (ees | ee ay |) al fg Pik see TSR IGS Nae a a CU SEE Pn ie DE CEG I TE AAS A Pa) | Sey Fo NA 7 tl (Pale 2 | 1 Misys 2a oe Fee Nee EPO e Day TR Ei sated ee LL 17 (ap J) 0 1 3} 10} 15 6 | 15 9 Total number of diseased bugs, 105. It is possible that bottles 21-80 had more spores attached to them than those in the other bottles, but that the spores possessed viru- lence is shown by the results in mortality. ELaperiment 4.—This experiment was begun May 17. Forty-eight screw-capped bottles, each containing an equal amount of earth, were sterilized in an autoclave. Twelve adult chinch bugs were then placed in each bottle. Twenty-four bottles were kept as checks (uninoculated), and 24 were inoculated as follows: Thirteen bottles by allowing bugs to crawl over spores from a culture and 11 bottles by scattering similar spores into the bottles with a camel’s-hair brush. The brush was rolled in a mass of the spores in a petri-dish culture and then struck sharply against the lip of the bottle. A cloud 24 THE WHITE-FUNGUS DISEASE IN KANSAS. of spores was thereby dislodged, which so filled the bottle that every chinch bug must have come into contact with them. On May 22 the results were as follows: Bottle No Number of diseased bugs. Mnoewlptedietes - Soo. cbasndeancRecstesecakedenia AM Sl LON U2 ato Le On SUE hike tesa tee temas Cees eS ay Se Oe ee ee cet aoe O91 CO ON ON On Oe aan eae 1 BOG NOC eeien ob dice ceases ce oo aera see epeineste 14 |15] 6 | 17 [as | 10 | 20 | 2 za | 20 | 24 Total. Number of diseased bugs. Tmoculated ss. assess na wociiee aksiewtnne eae (0 a elon LON VOOM ol) sai LON ST ORS 227 HOCK Sie raat oct ac a ste Ree ate eae eres = ON Lo) On ON OU xOn) helen nO eZ meen 12 Eaperiment 5.—The last of the series on virulence was begun on July 14, this late date being selected for the reason that the cultures then in the laboratory had been running saprophytically since the original isolation of the fungus in January, 1910, and there was a question whether such prolonged cultivation on artificial media had had the effect of lowering the virulence and hence weakening the power of the fungus in attacking chinch bugs. As the latter part of July was the time in which the field experi- ments were terminated, it was pertinent to know whether the fungus used in field inoculation during June and July had retained the parasitic nature evidenced by the earlier experiments of this series on virulence. Experiment 5 was arranged to compare inoculations with artificially grown fungus with natural infection. Natural infec- tion was presupposed, since there was no field found where Sporo- trichum did not exist naturally to some, even though to small, extent. The method of procedure differed but slightly from that in experi- ment 4. Forty screw-capped bottles were partially filled with 100 grams each of moistened and thoroughly mixed earth. They were then sterilized with 15 pounds pressure in an autoclave. Ten adult chinch bugs were placed in each bottle. Twenty bottles were infected by the camel’s-hair brush method described in experiment 4. The other 20 were checks. The bottles were watched, and it was soon noticed that Sporo- trichum was appearing among the treated bugs at a much faster rate than among the untreated. The disease in the checks was undoubt- edly introduced with the bugs and was present on them when they were collected from the field. But the same amount of natural fungus approximately would be present in the bugs in the inoculated bottles, so that final results would be but little affected. INFECTION EXPERIMENTS IN LABORATORY. 25 The bottles were opened July 23 and the number of Sporotrichum- covered bugs ascertained. CHECK BOTTLES. IDO WG IN@soc he aceecdence ae Saree Goes DaDP OBE ee RSASoc ACE 1 Ze PSone AM eOn| Om Eres imo LOm Lh INumiberondisessed DUPGS. . .- = ~~ 226 acccaececisc see re nS on ae ay ee ra Fane fess a ee Late See Str anaees eee apene ese ine fe rok wh | eile is Tate ie % ie re ee Rs ee ee eee lee att lpn cohanitamliba ds 9 Bottle Nos peu as ses cted: bse eee eh ia; ERS. -8 Dee Sra eee op WeOrilen se8in|) Osi LON era ee re rics by icant aioe te fee IB OTULO RIN Om see et cise aie ee iar terete acini Wemesmei seis 12 | 13 4 fs " =| 18 | 19 | 20 A Niummiber olvdiseasedbbmgsessasceet ae. os: Seis so- ce cee eee Fafa] sfofa] 2] of afo 63 The five experiments pointed uniformly to one conclusion—that no mistake had been made in adopting artificially grown fungus in pref- erence to that found on dead bugs, especially when it was found that so much more could, with certainty, be procured. In a great major- ity of instances in which field inoculation was undertaken the natural presence of the diseased bugs in large amounts would have rendered ineffectual the scattering of the comparatively few bugs obtained from infection boxes. Dr. M. A. Barber, director of the clinical laboratories of the uni- versity and inventor of the technique by which single bacterial cells or spores may be manipulated at will, conducted some inoculation experiments that shed light on the problem of virulence and infec- tiousness of artificial cultures. He has outlined his work below: In the following experiments spores of Sporotrichum globuliferum were inoculated directly into the bodies of chinch bugs by means of very fine pointed pipettes made of hard Jena glass. Very small quantities of an emulsion of spores in salt solution were drawn into the tip of the pipette by means of a suction on a rubber tube attached to the blunt end of the pipette. The point of the pipette was then inserted into the leg or abdomen of the insect and the spores forced in by gently blowing into the rubber tube. Inoculation was done under a large simple lens. The same technique has been successfully used in the inoculation of flies, cockroaches, and other insects with bacteria and various microorganisms. The experiments with chinch bugs were undertaken largely for the purpose of testing the technique, and the number of series undertaken 26 THE WHITE-FUNGUS DISEASE IN KANSAS. was too small to warrant any definite conclusions. The results, how- ever, indicate that chinch bugs may survive the injury made by the pipette, that direct inoculation into the body is more surely followed by infection than exposure to spores placed only on the surface of the body, and that introduction of spores into the abdomen gives a larger proportion of infections than inoculation into the leg. One series is given below as an example of the method employed. It differs, of course, from the natural one, but the technique is of service in testing the conditions of infection, as the virulence of spores grown artificially on culture media or the resistance of insects kept under different conditions or in different stages of growth. All chinch bugs used in the experiments were taken from the same lot, and all were inoculated with an emulsion in physiological salt solution of spores of Sporotrichum globuliferum taken from a 21-day agar culture. Twelve or more insects are included in each group. This culture was one derived from a series of transfers beginning with an original transfer made from a diseased chinch bug in January, 1910. Group.| Inoculated May 26. May 31. June 2. June 6. No apparent fun- gus growth; some bugs still living. Beginning of growth, appar- ently Sporotri- chum; growth first appearing on leg; all bugs 1 | In legs; at least con- tact of spores with injured surface. Majority of bugs covered with Sporotrichum. dead. 2 | Spores placed on un- | No fungus growth | No fungus growth | Several bugswith injured leg. apparent; some apparent; some S porotrichum; bugs still living. bugs still living. some still liy- | | men, nn | Controls; no spores added. Beginning of fun- gus growth; all bugs dead. Apparently no in- fection; some bugs living. All or nearly all covered with Sporotrichum. Apparently no in- fection; some bugs living. ing. Apparently all covered with Sporotrichum. Apparently no in- fection; at least one bug living. ARTIFICIAL INFECTION—FIELD EXPERIMENTS. The fungus material used in the following experiments was grown in the laboratory by methods already described. In the field the dried petri-dish cultures were rubbed up with dry earth, making a mixture that was light-colored, due to the large admixture of spores. The mixture was dusted directly on the bugs on the infested wheat or corn, and on the ground at the base of wheat, where the insects congregated. Shading experiments.—To test the effect of shade, artificially pro- duced, on Sporotrichum in its parasitic relation to chinch bugs, small ARTIFICIAL INFECTION—FIELD EXPERIMENTS. 27 plots of shade-giving, low-statured plants were set out in certain badly infested wheat fields. Shading experiments of a different na- ture were tried in cornfields, but these will be discussed in another place. The plots were set out to beans or cowpeas, as the case might be (the former proving the better), and were 50 feet square. A row of beans a foot wide formed the four sides of the square, and four rows, each a foot wide, were planted across the square, 10 feet apart, so that they would intersect the wheat rows at right angles. The ap- pearance of each plot when finished was that of a gridiron. The original purpose was to provide such shade that chinch bugs traveling along the wheat rows would encounter the shade and the moisture conditions of the bean rows. The beans were planted thickly, so that when the plants grew to 8 or 10 inches in height the ground beneath them was moist when that elsewhere would be dry. It was hoped that the wheat would come into close connection with the bean rows, but this was not always the case. It was hoped, also, that the bugs would seek the shade, and thereby enter conditions which would favor the development of Sporotrichum. It was found, however, that the bugs did not collect under the beans to any extent, nor did they appear to pass across the rows except 1n a few instances. Hence the infection sown among the beans, or cowpeas, failed to gain a favorable opportunity to come into contact with the bugs. While as a shading experiment the bean plots were of no value, they served a most excellent use as areas of infection or centers of infection. As they were laid out directly in the wheat they contained chinch bugs in as great numbers as the wheat outside them. Fungus was sown in them in large amounts, so that one might expect one of two results: (1) The chinch bugs inclosed by the plots showing greater mortality by Sporotrichum; (2) the plots becoming centers of field infection, with the greatest effect seen nearest the plots themselves. In most instances the experimental areas exhibited spontaneous outbreaks of Sporotrichum, and, with the fungus sown artificially, the plots con- tained an extensive amount of infectious material. In each experi- mental field, where a 50 by 50 foot experimental area was inoculated with fungus spores, a check area, or plot, similar in every way, was laid out from 100 to 200 yards distant. By comparing the two plots the effect of the artificial infection could be judged better. The spread of the disease, if any occurred, was watched not only in the experimental areas but in other parts of the field and in fields at distances from a fourth of a mile to several miles. Artificial infection—Localities in which field experiments were conducted.—In the selection of fields for artificial infection the first prerequisite was the presence of large numbers of chinch bugs, since a contagion of any kind spreads faster, other things being equal, 98 THE WHITE-FUNGUS DISEASE IN KANSAS. where congestion is greatest. A second desideratum was the scatter- ing of the centers of field work in such a manner that results would be general for the entire infested area of Kansas rather than local in character. Varied conditions would then be encountered; for ex- ample, one section would have less rainfall; another lighter soil; one with Sporotrichum abundant in the soil, another with it scarce. As to extremes of latitude, one county in the northern portion of the State and three along the southern border were chosen. With these things in mind, the following sections of the State, with the towns near which activities were carried on, were selected : South-central section: Wellington, Sumner County. Middle-central section: Newton, Harvey County. North-central section: Lebanon, Smith County. Southeastern section: Cherryvale and Independence, Montgomery County ; Fredonia, Wilson County; Parsons, Labette County ; Thayer, Neosho County. Middle-eastern section: Colony and Garnett, Anderson County; Lebo, Coffey County. Field notes covering observations made at intervals were, of course, carefully taken. Records of precipitation were furnished by a local or near-by observer in the Weather Bureau service. In a few in- stances rain gauges were provided and records kept for the immediate vicinity of the experimental farms. The method of procedure in each locality was essentially the same. Until wheat harvest, artificial infection was confined principally to the wheat fields, though in a few instances oats and young corn, when badly infested, were also treated. Fields in which chinch bugs were particularly numerous were deemed best suited for artificial infection. Several such fields were generally selected, the owners’ consent ob- tained, and either 50-foot plots laid out or inoculation made of some definite corner, side, or marked spot. The experimental fields were examined before any infection was set out, to ascertain, if possible, the presence of the fungus naturally in the soil. Direct observation of fungus-covered bugs was one kind of evidence used. If these were lacking, as was the case earlier in the spring, when dry conditions prevailed over the entire State, sterile bottles filled with bugs and earth were used, with the expectation that the fungus would break out spontaneously on the bugs when in moist conditions under confinement. In almost every instance the experi- mental field was thus shown to contain Sporotrichum before any spores were sown artificially. The only reason for continuing with the artificial inoculation experiments was to determine whether the extra amount of infectious material added would induce an epidemic, when under normal conditions only a slight outbreak would occur. Check fields, uninoculated and at distances varying from a quarter of a mile to several miles, were carefully observed, as they consti- tuted the key to the situation. ARTIFICIAL INFECTION—FIELD EXPERIMENTS. 29 It will not be necessary to give the field notes for all the localities in full, since a few will suffice to show how the work was conducted. Sumner County.—Attention was first called to the vicinity of Wel- lington, in which chinch bugs promised to be extremely troublesome. Collections of the bugs early in the spring confirmed the report. Sporotrichum was known to be present in the soil because of its presence in the bottle culture used as tests. The use of three wheat fields was kindly permitted by Messrs. Lynch, Banks, and Russell. Other farmers offered the use of their fields, but the three mentioned were found to be the most favorable in point of wheat prospects and numbers of bugs. The experiments on two of them will be described in detail. Experiments in Mr. Lynch’s field—Two plots, 50 feet square and planted gridiron fashion, with a dwarf variety of beans, were set out about 150 yards apart in the wheat field northwest of the Lynch residence. The plots contained approximately the same number of bugs, but the wheat was ranker in one than in the other. It grew finally so tall and close that its shade greatly exceeded that given by the beans. The beans were sown in the latter part of April, but it was not until about May 18 that the plants were high enough to make sufficient shade. On May 18 the field was examined for chinch bugs dead of Sporotrichum that existed naturally in the soil. They were found in both plots; also in other parts of the field. The part selected for artificial infection was near the center of the field, by an old strawstack. The check plot was that containing the ranker growth of wheat. Owing to the shade in the check, the conditions for fungus development were deemed better, but, on the other hand, the plot with the thinner growth contained more spores, owing to the artjficial infection. About 20 dried petri-dish cultures were stirred into a bucket of dry soil, and the mixture, whitened with the spores, was sown along the wheat rows and under the beans. There was no doubt but that the swarms of bugs around the wheat came into close contact with the infection. In addition, they jostled almost continuously the whitened corpses of bugs, already dead of the Sporo- trichum disease. A shading experiment, in which straw was used, was conducted near the infected spot. Small piles of straw were laid both between the wheat rows and around the wheat. Fungus-infected earth was then liberally sown in the straw and under it. The straw was util- ized to keep the ground beneath moist, so that if bugs frequented the straw to any extent they would find conditions more favorable than out in the open. Many would contract the disease, perhaps, and then leaving the piles die in other locations, thus scattering the infection. On May 25 a second and thorough infection of the previously infected plot and straw piles was made. At the same time results 30 THE WHITE-FUNGUS DISEASE IN KANSAS. of the previous inoculations were looked for and the general situa- tion examined. Diseased bugs were found in both plots, more being found in the check. Recent rains that had moistened the soil now showed no effect on the surface, except where the wheat was rank. Bugs were dead in all parts of the field, and in many places the dead bugs were as numerous as in the infected plot. Under the straw that had been packed around the wheat there were more diseased bugs found than anywhere else; but there were no more, apparently, near the piles than at a distance from them, so that the infection had not spread, to any appreciable degree, at least. Chinch bugs, young and old, swarmed along the wheat rows, with no more dead ones in the infected plot than outside of it, or in many other parts of the field. Clearly the artificial infection had yielded no results. The wheat was showing the effects of dry weather as well as the attacks of the bugs. It was found that the beans gave entirely negative results. While the ground remained moist longer beneath them, the chinch bugs did not frequent them to any extent. On June 12 the Lynch field was again visited. The greatest num- ber of living, as well as of diseased bugs, was found in the check plot, with its rank wheat. Conditions elsewhere were about as they were on the previous visit. The wheat had turned yellow and was nearly ready for harvesting. In the 25 days since the first infection in which the artificially sown fungus had been allowed to act, the moist conditions resulting from two periods of precipitation had favored the growth of Sporotrichum. On the whole, however, the period had been dry. The drought had not prevented a general spontaneous outbreak, but it probably checked its severity. The artificially infected plot had not only the bugs dead of the Sporo- trichum naturally present, but it had relatively enormous quantities of culture fungus, so that as to intensity of infection it was much more thoroughly treated than would have ever been possible with diseased bugs, or than it would have been had the spores been spread over an entire field. The artificial inoculation was a failure in that it did not perceptibly decrease the number of bugs in the 50-foot plot, when compared with the area about it and with the check; nor did the fungus spread from the treated plot or the straw piles. The check had more diseased bugs than the treated plot, but this may have been due to the moister conditions produced by shade or to greater numbers in the first place. Apparently the presence or ab- sence of the culture fungus did not affect the problem. As check fields to the Lynch fields, three were examined, the near- est being about a fourth of a mile distant, the other two one-half and three-fourths of a mile distant, respectively. None had been artificially infected, yet each contained diseased bugs. ARTIFICIAL INFECTION—FIELD EXPERIMENTS. 31 Experiments on Mr. Banks’s place—The field offered for experi- mental use was on a slope south of the house. Like the Lynch field, one had contained a rank growth and the other a thin stand of wheat; but the rank growth was denser and the thin growth was poorer than that found on Mr. Lynch’s place. In order to balance matters the bean plot set out in the dense growth of wheat was used for artificial infection, while that in the thin growth served as a check. It was noticed that diseased chinch bugs were present in all parts of the field before any fungus had been distributed. The first inoculation was made May 18. Cultures were mixed with the earth and sown as in the Lynch field. The beans were useless, as they were shaded by the wheat. The ground was moist in both plots, and especially in the treated one. Observations were taken May 25. Both plots, as well as the remainder of the field, contained diseased bugs, but the dense growth showed the greatest number, outside the plot as well as in- side. Had not the Lynch field served as a kind of control these results might have been regarded in part as favorable to artificial in- fection. On the same date (May 25) a second distribution of fungus was made in this plot. Final observations were taken June 12, but there was no change in the results. The favorable conditions of shade and moisture favored Sporotrichum. No matter whether fungus spores were added or not, about the same number of bugs died, and there were more than in a plot where the sun had a better access to the soil and where conditions were drier. The fungus showed no tendency to spread. The bugs had begun to migrate into the neigh- boring oats and the cornfields. A wheat field about a fourth of a mile distant, untreated, contained many diseased bugs. Other check fields were the Cann place and the Ruggles place, both about 3 miles dis- tant. Diseased bugs were plentiful in all of them. Weather conditions.—Statistics as to humidity and precipitation for the district around Wellington were kindly gathered by Mr. BK. O. G. Kelly and his associate, the former an assistant in the Bu- reau of Entomology of the United States Department of Agriculture. The recording instruments were kept at the station, which was approximately the center of the area that would include the three experimental fields. Observations covered most of May and June, during which field investigations were going on. Total precipitation recorded by Mr. Kelly, 6.13 inches. The total for April, May, and June at Rome, a few miles south, was 6.27 inches. The spring and early summer were unusually dry, as the average monthly rainfall for the district around Rome was lower than the normal by the following amounts: April, 1.59 inches; May, 1.23 inches; and June, 3.32 inches. In spite of the diminished precipita- tion, however, spontaneous outbreaks of Sporotrichum occurred all about Wellington, no field containing chinch bugs failing to exhibit the whitened, fungus-covered bugs. 10944°—Bull. 107—11—_—-3 32 THE WHITE-FUNGUS DISEASE IN KANSAS. North-central section, Smith County, Lebanon.—For this section Lebanon was selected as a favorable place for carrying on some field experiments. Accordingly, one of the writers went to Lebanon, April 18, and with the assistance of Dr. W. C. Bower and Mr. Charles Isom selected five fields in which to experiment. The details of the work in one field only, that of Charles Sargent, will be given, as the results in all these experiments were the same. At the time of our visit it was very dry. On the 20th a severe dust storm prevented us from going to the country. The bugs were plentiful in all the fields visited, but no diseased bugs were found. Laperiments in Mr. Sargent’s field—On April 21 Mr. Sargent’s field was examined for diseased bugs, but none was found, though living ones were abundant. On May 10 a supply of Sporotrichum was sent to Mr. Sargent with which to infect his field. On May 12 it was mixed with earth and distributed along a small draw where bugs were thick, wheat was rank, and moisture conditions were fa- vorable. Small bunches of straw were also infected. The field was examined May 31 for results. Occasional dead bugs could be found in all parts of the field, but, on the whole, diseased insects were scarce. There were more of them, however, in the draw where the infection was placed than elsewhere, but this might have been caused quite as much by the more favorable conditions there as by artificial infec- tion. ‘There seemed to be a few more diseased bugs also in the im- mediate vicinity of the bunches of straw than at a distance of a few yards away, but the difference was so slight that the experiment could scarcely be called successful. On the same date Mr. Moore’s field, 1 mile south, and Mr. Waddles’s field, 1 mile north, were inspected, and diseased bugs were found in both of them, though they had not been infected artificially. There was no appreciable difference in respect to the number of dead bugs in the fields. On this date (May 31) a second distribution of fungus was made in the draw. Spores were dusted directly from the cultures upon the bases of the wheat, where the bugs were most plentiful. This was done in two definite areas, which were carefully marked. During wheat harvest, June 28, the field was again visited. Dis- eased bugs were much more numerous all over the field than at the time of the previous visit. Especially was this true along the draw where in some spots the diseased bugs were thick enough to whiten the ground. In and around the two infected spots, however, there were no more diseased bugs than in equally favorable spots elsewhere. Young bugs were still swarming in the wheat in vast multitudes, so that the fungus did not materially help the field, though a good many died, especially among the old bugs. Two factors may have been at work in the outbreak of Sporotrichum; one, the artificial infection, the other, the favorable conditions acting in conjunction with the ARTIFICIAL INFECTION—-FIELD EXPERIMENTS. 33 fungus naturally present in the soil. In analyzing the factors, the distribution of the dead bugs was taken to be the important element. A search of the field showed that they were thicker in some parts than in others, but numbers were related to conditions of moisture rather than to centers of artificial infection. Hence it is not improbable that the situation would not have been appreciably altered had no fungus been sown in the field. Other fields near Lebanon in which no Sporo- trichum had been introduced, or at least not until a later date, were used as checks, and particularly the Moore field, 1 mile south, and the Waddles field, 1 mile north. They were examined carefully on the same dates as the Sargent field, and at no time was there any percep- - tible difference, so far as diseased bugs were concerned, in the three fields. All the check fields contained diseased bugs in considerable numbers, especially where the conditions were particularly favorable. Owing to artificial infection of the Sargent field before the time was ripe for a general spontaneous outbreak of Sporotrichum, the occur- rence of the outbreak in this field had all the appearance of being due to the sowing of the fungus. Toa casual observer the success of arti- ficial infection would have been regarded as indisputable, though of course partial, since not all the chinch bugs were killed. It is likely that some of the “successes” reported by farmers in former years were due to a misinterpretation of such appearances of Sporotrichum among the bugs. The results of the experiments at Lebanon showed the importance of moisture conditions as factors in the development of the Sporo- trichum disease, especially in a dry season, and at the same time how unimportant a factor is the sowing of the fungus spores. Total precipitation at Lebanon for the months of April, May, and June, 1910, 6.85 inches, which was 2.08 inches less than the average. For May, however, the rainfall was 0.04 inch greater than the aver- age. The greatest deficiency in precipitation was during April. Southeastern section, Montgomery County, Cherryvale—Three farmers near Cherryvale kindly offered the use of their wheat fields for experimentation. They were Mr. Metcalf, Mr. Benham, and Mr. Darling. The vicinity of Cherryvale was badly infested with bugs and hence offered a favorable opportunity for experiment. The east- ern portion of the State, moreover, exhibited better climatic condi- tions, owing to greater rainfall and humidity. On April 27 collection of bugs and earth in sterile jars was made from each of the three fields mentioned above. Sporotrichum de- veloped readily, thus showing the presence of the fungus naturally in the soil. On the Benham and Darling places, 50-foot plots of the usual type were set out to cowpeas and placed about 100 yards apart. The cowpeas did not prove of any advantage as to shade, and so the plots were used to mark the areas for infection and check, 34 THE WHITE-FUNGUS DISEASE IN KANSAS. Experiments in Mr. Metcalf’s field—This field was located about 4 miles north of town and was the worst infested place seen around Cherryvale. No plots were set out, but the infection of it was left in the hands of Mr. Metcalf himself, who scattered the fungus gen- erally over the field. On May 2 a large package of fungus culture was shipped, with instructions as to mixing with soil and distributing through his field. On May 13 a second lot was sent, and a third shipment was made May 22. On May 26 a visit was made to the field. Up to this time there had been two artificial distributions of the fungus culture, and also several of diseased chinch bugs taken from an infection box. Living bugs were exceedingly numerous, and the conditions for their destruc- tion by Sporotrichum were to all appearances ideal, as rainfall, a moisture-retaining soil, and high humidity for much of the time conspired to render the spread of the fungus easy. An outbreak of Sporotrichum occurred early in May, and by May 26 had succeeded in killing many thousands of chinch bugs, so that they were plainly in evidence on the ground all over the field, yet so numerous were the living ones that the dead ones were at any time only a small per- centage. Had not the check fields been watched, the outbreak might have been attributed directly to an artificial infection. In fact, it seemed to Mr. Metcalf, at least at first, that the fungus he had sown was quite successful, especially as he had put it out before any appear- ance of diseased bugs was manifest. But spontaneous outbreaks occurred in all the fields examined around Cherryvale at about the same time, and no difference was noticed as to whether a field had been artificially infected or not. One can readily see how a farmer, observing the state of affairs merely on his own place, would be con- vinced of the success of his artificial infection and would send in his report accordingly. So plausible was the evidence to Mr. Metcalf that it was only with difficulty that he was convinced after visiting a check field owned by Mr. Steinburger and located 1} miles distant. The Stein- burger field was nearly as badly infested as was Mr. Metcaif’s, and the diseased bugs appeared more numerous than on his own, though no artificial infection had been used. On this date (May 26) the Metcalf field was artificially infected by fungus culture for the third time. The amount of fungus added to the field was, of course, a small proportion of that found naturally on the thousands of dead bugs scattered through it. On June 23, about harvest time, the field was again visited. Conditions were found to be about the same as on the previous visit. Two check fields other than Mr. Steinburger’s, lying about 2 miles distant, were used for comparison. Both had numerous living bugs and as extensive spon- taneous outbreaks of Sporotrichum as any field around Cherryvale. ARTIFICIAL INFECTION—FIELD EXPERIMENTS. 35 Montgomery County, Independence.—The experiments conducted at Independence were under the supervision of Leslie A. Kenoyer, a graduate in science of the University of Kansas. Mr. Kenoyer lived at home, on the farm, while carrying on his work, and was therefore able by constant residence to watch the progress of events in a most satisfactory manner. His observations, however, were checked up from time to time, His final report is given below in full. Mr. L. A. KENOYER’S ReEporRT OF HIS EXPERIMENTS WITH SPOROTRICHUM AND THE CHINCH Bue. My observations on chinch bugs near Independence, Montgomery County, Kans., covered a period of nearly three months—from March 20 until June 14, 1910. The bugs were found to occur in most grain fields. They were, as a rule, most abundant near the borders of the field, and especially adjoining hedges of Osage orange. These hedges are numerous in this county and they appear to be excellent harboring places for the bugs, chiefly, it appears, by reason of the weeds and grass which collect there. Even spring burning does not seem to destroy the bugs. Dr. F. H. Billings and I planted bush beans around several selected plots of grain about April 15. The plots chosen were 50 feet square. A trench 1 foot wide was made around each and four simi- lar trenches were placed across the square at intervals of 10 feet— the whole having the form of a gridiron. The beans were thickly sown in the trenches. In the Evans and the Page wheat fields two plots in each were thus arranged, the one to be infected and the other to serve as a check. In the Kellenberger oat field one plot was planted and kept infected. In the Evans wheat field two plots of the same size and appearance as those planted to beans were laid out by means of strips of old straw 1 foot broad. One was infected and the other left as a check. In a neighboring field small piles of straw and of fresh weeds were placed at intervals and kept infected. The end sought in these experiments was a method of supplying shade and moisture enough to encourage the development of the fungus. Fungus grown at the University of Kansas on a preparation of corn meal and potato extract was pulverized, mixed with dry dust or sand, and scattered in the bean rows and strips of straw. In the Page field the plots were planted just south of a hedge, along which were a good many bugs in the spring. The plots were about 60 rods apart. The west one was infected May 7 and May 14. As the bugs seemed to diminish in numbers along the hedge, no more fungus was placed in this field. At the last examination, June 11, a few living and a few fungus-covered bugs were found in both 36 THE WHITE-FUNGUS DISEASE IN KANSAS. places. Both living and dead seemed to be rather more numerous in the noninfected plot, but the results were indecisive. | Fungus was sprinkled on the bean plot in the Kellenberger oats field May 7, May 14, May 26, and June 4. Bugs did not become plentiful in this field and very few young ones appeared. There were a few more, both living and diseased, in and about the infected plot than elsewhere. .But wherever there were living bugs, diseased ones could be found by a little searching. In the Evans field the bean plots were located just north of a hedge and about 40 rods apart. The east plot was infected on the above-mentioned dates. Bugs continued very numerous all spring in this field. Hordes of young ones appeared about the middle of May and their influence, added to that of an early spring drought, killed much of the wheat before it was ripe. Fungus developed all over the field so freely that by the middle of June from 50 to 100 dead and whitened bugs could frequently be found around the bases and on the roots of a single hill. While the fungus appeared in all parts of the field it was in general more abundant at the west end, so it chanced that the uninfected bean plot showed decidedly more fungus than the infected one. The “ east” straw plot was infected on the same dates as the bean plot and the “ west” plot was left as a check. On neither one were the bugs as numerous as along the side of the field on which the beans were planted, but both living and dead bugs were to be seen in about equal numbers in the infected plot and the check plot. The piles of straw and those of weeds were likewise infected, but without any appreciable increase in the death rate of the bugs. Although the beans had made a very good shade before harvest time, the bugs showed no marked tendency to seek the shade. They are more active on sunny days than in cool, cloudy weather, and when crawling from hill to hill they appear to seek sunshine rather than shade. After the wheat had ripened the bugs crawled up the bean bushes in considerable numbers, and many dead fungus-covered bugs could be seen adhering to the leaves of the plants and to the young beans. Famine had evidently aided the plague in this case. But here again there was no difference in favor of infected portions. To determine the efficiency of the distribution of dead bugs in fields I selected an oats field on the Evans farm, one-fourth of a mile from the experimental wheat field. A strip of about 3 by 10 yards was sprinkled on May 25, May 28, and June 4 with diseased bugs grown in culture boxes. Developments on this portion were in no way different from those on the remainder of the field. On April 20 a pint fruit jar was scalded and half filled with bugs and soil from the Evans wheat field. Sporotrichum developed in ARTIFICIAL INFECTION—FIELD EXPERIMENTS. ot from 8 to 10 days, showing quite conclusively that the spores were present in the soil. In a field of wheat and in one of rye, west of the infected fields and about three-fourths of a mile distant from any of them, diseased bugs were found in the early part of June in as great numbers as in the Evans field just mentioned. The chance of material from my infections having reached these fields was very improbable. Several other fields were examined and none was free from infected bugs where bugs were plentiful in the period preceding harvest. But the proportion of diseased bugs varied considerably from field to field. And apparently in no case had the fungus produced an epi- demic sufficient to materially reduce the number of bugs or to save the crop. My experience with infection boxes was not such as to greatly encourage the infection idea. Living bugs were confined with dis- eased ones in boxes of moist earth for weeks at a time, and only a very few became infected. Later in the season, when the disease became common in the fields, it spread more readily in my boxes. My observations lead to the following conclusions: 1. Sporotrichum occurred naturally in the soil of all of the fields. 2. The distribution of the spores or of spore-covered bugs in a field had no noticeable effect upon the dying of bugs. 3. Bugs died spontaneously when the weather was sufficiently moist and when the ripening of the grain diminished their food supply. 4. Spontaneous infection did not spread to such an extent as to materially benefit the crop. . The results attained in the precedinggreport were confirmed by ob- servations made during the experiments. The results fully accord with those obtained elsewhere, and are of particular value because of the favorable moisture conditions and the larger number of chinch bugs. In the Evans field the young bugs suffered more severely by attacks of the fungus than in any other field investigated. Weather conditions for Cherryvale and Independence.——The weather statistics for these two centers of experimental work were gathered by Mr. F. L. Kenoyer, of Independence, and we hereby express our thanks to him for his kindness in taking humidity read- ings and furnishing a copy of the precipitation record. During the month of May and the fore part of June, southeastern Kansas had a rainfall in excess of the average and a relatively high humidity. The soil in this section, being mostly heavy, retained the moisture well. The conditions for fungus propagation seemed to be ideal dur- ing a part, at least, of the period of growth of the new brood of chinch bugs. While adults seemed to succumb first, many young were affected, especially at Independence. 38 THE WHITE-FUNGUS DISEASE IN KANSAS. The total precipitation at Independence for the months of April, May, and June, 1910, was 10.97 inches, which was 4.70 inches in excess of that of Rome (near Wellington, in Sumner County). The rainfall for May alone at Independence was 6.25 inches, or about the same as for the three months near Wellington. The May precipitation was 6.25 inches, or 1.44 inches in excess of the average. In addition to the unusual total precipitation for this month, the rainfall was well distributed. There were 19 cloudy days in May, and 5 partly cloudy, so that the month was damp for most of the time. Conditions were very favorable for Sporotrichum from the first week in May until the harvest time, and it was certain that the fungus responded by attacking vigorously both young and old bugs. Notwithstanding the favorable conditions, there were plenty of bugs left at harvest time— enough to do great injury to the corn. Anderson County, Colony and Garnett—The experiments of Col- ony only will be outlined below. Two fields were used for experi- ment, but the field notes taken on Mr. Quiett’s place will suffice for the purpose. Experiments on Mr. W. A. Quiett’s place-—Work began on Mr. Quiett’s place on April 20, when a field of wheat was searched for diseased bugs. While none was found, living bugs were numerous, and two bottles of bugs and earth were collected to see if Sporo- trichum would develop spontaneously. The results were negative. Diseased bugs were left with Mr. Quiett, so that he might start an infection box. On May 3 a supply of fungus culture was sent for field infection. It was distributed along the north side of the field. On May 19 the field was examined for results. Two diseased insects were found on the north side near the infected locality, but none was seen on the south side. It was evident, as in the Boone field, that no spontaneous outbreak had occurred. Some of the fungus had been placed under piles of straw, but there were no results in dead bugs. There had been more or less rain for about three weeks and the soil was wet. Another visit was made May 26, with no change in the condition of the field. Weather was cool and damp. Some fungus was placed at the base of the wheat in a small patch that was carefully marked. A similar patch some distance away was infected with diseased bugs and also marked. Some living bugs from the field were caught, shaken in a box with Sporotrichum spores, and then turned loose under a bunch of straw. The experi- ments on this date (May 26) were concluded by leaving a quantity of the fungus culture with Mr. Quiett for further field infection. The next inspection took place June 21. All parts of the field were searched for diseased bugs. Extremely few were found, and no more around the infected spots than elsewhere. The ground was damp and shaded in some places, but there were no more in evidence in ARTIFICIAL INFECTION—FIELD EXPERIMENTS. 39 one place than in another, so far as could be seen. Harvest had begun before another visit was made, on July 12. The bugs had gone into some adjacent corn. Pupz were very thick on the ground about the base of the stalks, under bunches of crab grass and other vegeta- tion that afforded protection. Adults were emerging in large num- , bers. A few diseased bugs were found in the corn where the bugs were collected for molting. A pile of cut corn was made in the field and fungus scattered in it. A second pile was made and left unin- fected. On July 30 an inspection showed that diseased bugs were still scarce, only one being found. The infected and check piles of cut corn and the locality immediately adjacent showed no effects of the infection or shading. Both piles of corn contained thousands of molted skins of the bugs, which might have been taken by an un- skilled observer for dead bugs. Results of experiments in Anderson County—Conditions at Gar- nett and Colony were unique when compared with all the other places where experiments were made. Spontaneous outbreaks of Sporotrichum had been the rule, but at Garnett and Colony they were absent, or nearly so. To explain the situation, one would natu- rally examine the climatic conditions, since they probably have more to do with the propagation of Sporotrichum than any other factor. The following table gives some comparative data: May and June. Place. eae Me: Precipi- tation. | ‘emper- Inches. SEE: Gamethccccc-ceeeas 2 Siepeaicta tae Oe terete Aye 11.31 65.5 pumers G@Zarsons) 22s ee ee ee 9. 61 68.0 We Mis SCeee ema em clo wiah mimesis paces 12. 46 65.6 Bae GWellinte tom) assee te res Tee Res 4.67 68.8 GD ANON oe te aoe oA esa eee aatls 6.19 65.1 erate (Thayer) Be DAY eas 13.69 65.5 MMO epenGencekaace seen. eee peo 9,21 68.1 Eten InSOneee es: See ey eee es ches 67.1 Garnett had an abundance of moisture, but the spontaneous out- break was only slight. Conspicuous outbreaks occurred at Lebo and Thayer, where the precipitation was greater, at Parsons and Inde- pendence, where it was but a little less, and at Wellington and Lebanon, where the precipitation was much less. The mean tempera- ture for the two months was below normal, but not below the mean temperature of other places where spontaneous outbreaks occurred, for example, Lebanon and Thayer. It would seem, therefore, that the explanation of the fact that spontaneous outbreaks in Anderson County were so meager can not be found in the climatic condition, and must be attributed to some other factor. Was it due to a scarcity of fungus naturally present in the soil? This would seem to furnish 40 THE WHITE-FUNGUS DISEASE IN KANSAS. a plausible explanation at least, since our tests in nearly every case yielded negative results. But when large quantities of the fungus were introduced the results remained unchanged; no epidemic could be started. It seems evident, therefore, that the failure of an out- break to occur was not always due to the lack of the fungus, but to some other factor as yet unknown. If these two places in Anderson County are representative of those in which spontaneous outbreaks do not seem to occur, then it is evi- dent that artificial infection does not produce such outbreaks or any beneficial effects that are commensurate with the amount of fungus introduced and the time and expense necessary in introducing it. Corn-infection experiments at Cherryvale—The field work at Cherryvale was more extended than at Independence and the climatic conditions were more favorable, especially during the first part of the work. The fields selected were owned by Mr. Metcalf and Mr. Botkins. They were separated by a wheat field, from which chinch bugs migrated. By the 21st of June about the first 20 rows of corn were badly infested. Two plots of corn were selected in the Metcalf field, at opposite ends of the corn rows nearest the wheat. The plots were surrounded by ridge barriers on which crude oil was placed. Each area had about as many bugs in it as the other. Both were very badly infested, and the corn gave promise of being quickly killed unless the bugs were exterminated. One of the plots was artificially infected with fungus culture. The spores were mixed with earth and dusted on the bugs. Some of the dried cultures were used with- out an admixture of earth. The insects swarmed on the corn in such compact bunches that large numbers could be easily dosed with fungus spores. Practically all of the bugs in the plot had an appli- cation of Sporotrichum. The other plot was used as a check. Each plot was about 40 feet long and included three rows of corn. The experiment continued for a week, or until the corn was completely killed out. The bugs were unhurt and finally escaped over the barrier and scattered into the new corn. A new type of experiment was then tried, the chief merit being the maintenance of extremely humid conditions. The other factors, large numbers of bugs and intensity of infection, were still at hand. The experiment consisted of cutting corn badly infested with bugs and piling it in heaps, bugs and all. In the Metcalf field about a dozen stalks composed each. The top soil under each pile was removed to expose the damper subsoil, which thus assisted in preserving the dampness. The bugs repaired to the lower portions of the piles as soon as they were made, and there, with the moisture from the leaves, from the ground, or from the rain, or artificial watering, the humidity was high enough to insure propagating of the fungus. ARTIFICIAL INFECTION—-FIELD EXPERIMENTS. 41 In the Metcalf field six piles of corn were laid. Two were well watered and two of the remaining four were covered over with rank weeds to increase the shade. The last two were not watered nor cov- ered with weeds. All were thoroughly infected throughout with Sporotrichum. Chinch bugs swarmed inside the piles and as long as the corn remained reasonably fresh they apparently made no effort to leave. A similar series of piles was constructed in the Botkins field, only they were larger, having 40 stalks to the pile. A dozen such heaps were made, and they were about 60 feet apart. None of the piles in the Botkins field was artificially infected. Four questions were to be decided by the corn-pile experiment: (1) Would the chinch bugs become diseased in an uninfected pile? (2) Would they become so in an artificially infected one? (8) Would the infected bugs leave the piles and carry the contagion to other parts of the field and ultimately bring on an epidemic? (4) Would the bugs die by sucking the juice of the corn, soured after cutting, as had been stated by certain farmers? The piles were prepared June 22. Heavy rains occurred June 25 and 27, making the ground very muddy. Diseased bugs were noticed around the base of the corn in various parts of the field. The piles of cut corn were examined and a few dead bugs were found. The corn was very wet, and the lowest stalks and leaves in some of the piles were in mud. As the greater part of the leaves were still fresh, the bugs had not left the piles, but seemed quite as numerous as ever. If the juice had soured it had thus far caused no perceptible mor- tality among them. Molting had occurred to a considerable extent, and the old skins resembled dead bugs sufficiently to have probably caused some of the farmers to mistake them for bugs killed by sour juice or by Sporotrichum. The piles in the Botkins field, although ‘untreated, contained more diseased bugs than the artificially infected ones in the Metcalf field. Conditions were probably more favorable in the former than in the latter case, since the corn was piled on higher ground and did not get so soggy. Thus far no effect worth mentioning from Sporotrichum was ob- served in any of the piles. The diseased bugs in the piles on the Bot- kins place served as infection for the other bugs. It seemed as though conditions in this field could not have been made better for the spread of infection, yet the number of diseased bugs was only a very small fraction of the living. On this date (June 27) a pile of freshly cut corn infested with bugs was made in each field, the one on the Metcalf place being in- fected artificially with Sporotrichum. All of the piles were ex- amined on July 6. The original ones (made June 23) were found 492 THE WHITE-FUNGUS DISEASE IN KANSAS. to be deserted by the bugs, and the corn dry and in some instances moldy. Skins of molted bugs were very numerous, and Sporo-— trichum-covered carcasses were in considerable abundance, but aside from the latter there was no evidence of dead bugs, 1. e., that might have been killed by sour juice, for instance. Evidently the great majority had migrated, leaving comparatively few dead behind as the result of infection by fungus. The corn piles made on June 27 were in good condition, the corn being green and fresh. Chinch bugs still swarmed through them in multitudes, and there were old skins and quite a number of diseased bugs. There were a few more diseased bugs in the Metcalf corn pile than in that in the Botkins field, and the difference may have been chargeable to the artificial infection. The percentage of diseased insects when compared with living, however, still remained very small, so that as an effective means of propagation of Sporo- trichum disease, the corn piles were a comparative failure. Quite the reverse might have been expected, since the chinch bugs remained exposed for over a week to infection under shade and moist con- ditions. With negative results under such circumstances artificial infection could hardly be expected to work in the open field. Almost every chinch bug in the corn piles must have come into contact with the fungus spores sooner or later, especially where artificial infec- tion was used. After leaving the piles the bugs transported the spores to various parts of the field, but there was no evidence that the spores took effect. By July 6 nearly all of the corn in the full 50 rows was destroyed. Infection of chinch bugs on corn by the use of fungus culture was made on this date and again on July 17. Cultures mixed with earth or used directly were employed in dusting spores on the insects. Final observations were made on July 28, five weeks after the first lot of the fungus was sown in the corn. From a practical stand- point everything was negative. At no time did the Sporotrichum disease appear to be working except in the smallest way. Perhaps the weather conditions were not just right, but at Cherryvale they were apparently right for at least part of the time and that long enough to have started an epidemic. If the relation between climatic conditions and successful fungus propagation, however, is so exact that not once did anything like a really destructive epidemic occur during all the series of experi- ments and observations from April till nearly the first of August, then farmers should not for a moment think of depending on arti- ficial infection or on the fungus disease at all for the saving of their crops. Whatever good had come from Sporotrichum as a destroyer of chinch bugs came of itself without the aid of artificial sowing of spores. THE WHITE-FUNGUS DISEASE IN KANSAS. 43 RemMeEpIsL MEASURES AND CONCLUSIONS. The University of Kansas, during 1910, sent qut 1,363 packages of diseased chinch bugs at the request of farmers, with which to start infection boxes and artificially infect their fields. The plan followed was in accordance with recommendations of Dr. Snow, who in the nineties attempted to check the ravages of chinch bugs by the distribution of Sporotrichum globuliferum, the cause of the well- known white-fungus disease. ¥ a “~ 9 f apes aie 26 Y_-U. S. DEPARTMENT OF AGRICULTURE, aj - BUREAU OF ENTOMOLOGY—BULLETIN No. 108. L. O. HOWARD, Edinavloaist and Chief of Bureau. LEAFHOPPERS AFFECTING CEREALS, GRASSES, | AND FORAGE CROPS. BY HERBERT OSBORN, Professor of Zoology and Entomology, Ohio State University. IssuED SEPTEMBER 12, 1912. Wie= Ay AT AM AY —> pe Pos Ly Ae Vi ’ f/ oy : : UP \ » fy ~ tional Museu” WASHINGTON: GOVERNMENT PRINTING OFFICE. 1912. “235 £4.26. Yate 2. | al aed - * ; Eso EPART MENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—BULLETIN No. 108. L. O. HOWARD, Entomologist and Chief of Bureau. LEAFHOPPERS AFFECTING CEREALS, GRASSES, AND FORAGE CROPS. BY HERBERT OSBORN, Professor of Zoology and Entomology, Ohio State University. IssureD SEPTEMBER 12, 1912. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1912. BUREAU OF ENTOMOLOG Y. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Maruarr, Entomologist and Acting Chief in Absence of Chief. R.S. Cirrron, Executive Assistant. W. F. Taster, Chief Clerk. I’. H. CarrrenvEn, in charge of truck crop and stored product insect investigations. A. D. HWorxtns, in charge of forest insect investigations. W. D. Hunrer, in charge of southern field crop insect investigations. F. M. Wesster, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, tn charge of deciduous fruit insect investigations. E. F. Pures, in charge of bee culture. D. M. Rogers, in charge of preventing spread of moths, field work. Rouua P. Currie, in charge of editorial work. Mase Coxucorn, librarian. CEREAL AND ForRAGE INSECT INVESTIGATIONS. IF. M. WeBsTER, in charge. Geo. J. Reeves, W. J. Puruures, C. N. Arnsiiz, E. O. G. Ketty, T. D. URBAnNs, Harry S. Smiru, Gro. G. AInsuiz, J. A. Hystop, W. R. Watton, J. T. MoneELL, J. J. Davis, T. H. Parks, R. A. Vickery, V. L. WinpERmMuTH, E. G. Smyra, HERBERT T. Ossorn, Puitie LUGINBILL, C. W. CREEL, E. J. Voster, R. N. Witson, VERNON Kina, entomological assistants. Nertiz 8. Kioprer, ELLEN DASHIELL, preparators. Miriam WELLES REEVES, collaborator. 9 “ LETTER OF TRANSMITTAL. U.S. DEPARTMENT OF AGRICULTURE, BurEAvU OF ENTOMOLOGY, Washington, D. C., December 12, 1911. Sm: [ have the honor to transmit herewith, for publication as Bulletin No. 108 of the Bureau of Entomology, a manuscript entitled ‘‘Leafhoppers Affecting Cereals, Grasses, and Forage Crops.” This matter was prepared by Prof. Herbert Osborn, professor of zoology and entomology in the Ohio State University, the best known American authority on these insects. Prof. Osborn was a temporary agent of the Bureau of Entomology, and spent about fourteen months in the work, visiting, during the warm months, various parts of the United States, and studying these insects in the field, on the farms and ranches, under natural conditions. He was able to devote his whole time to this work during this period owing to the fact that the board of trustees of the Ohio State University kindly granted him leave of absence for one year. We have, in this document, the first effort made in this country to determine the exact economic impor- tance of these insects, together with the best methods of controlling them. Respectfully, L. O. Howarp, Entomologist and Chief of Bureau. Hon. JAMES WILSON, Secretary of Agriculture. ay L ie eae (haa . | we othe, A a 7 ‘ (our { eties ORG a tay, * Width Malo ons i P ke ; ; is 5 ; fil ry { ; WyriF) (ene i) Tb cia ‘ ‘ tay Saw au . + ' i A are p ' "int hi Ae ; i ; sey ae Fs ; . ott. a PRE PAGE: The present paper is designed to include the general discussion of the group of leafhoppers, with such matter as pertains to the group as a whole-and with the consideration of the species which have been recognized as of the greatest economic importance. It deals on this account particularly with those species affecting the cultivated crops, although there are many species which live upon wild grasses and forage plants of the western ranges that undoubtedly have an impor- tant relation to the extent of the pasturage they may supply. A second paper which is in preparation will deal more especially with the more technical aspects of the group, with a discussion of those species which are less noticeable as injurious species or which so far as at present known are confined to wild plants or to those of little cultural value. A knowledge of these is, however, important to economic entomologists, both for the sake of ascertaining their economic relations and as a basis for study in case they transfer their attacks to cultivated crops. In the collection of material for these papers I have had the hearty interest and assistance of so many different individuals that I hesitate to attempt an enumeration of them, knowing that some must almost certainly be omitted. As stated elsewhere, the work was made pos- sible by the interest of the officials of the Bureau of Entomology at a time when I[ had an opportunity to leave university duties, and for this interest and constant encouragement I am deeply grateful. At many localities and institutions where I worked I was given not only free access to collections and records, but the direct help of information as to available fields for observation and collection and often the advantage of personal direction and use of conveyances. In this way I am especially indebted to Mr. J.S. McGavren, of Missouri Valley, Iowa; the University of South Dakota; Prof. James Wilson, Brookings, S. Dak.; Prof. J. H. Sheppard, of the North Dakota Experiment Station; Prof. R. A. Cooley, of Bozeman, Mont.; Mr. George I. Reeves, of the Bureau of Entomology laboratory at Pull- man, Wash.; Mr. W. J. Phillips, of the laboratory at Lafayette, Ind.; Prof. S. A. Forbes and Mr. C. A. Hart, of the University of Illinois; the Carnegie Museum, Pittsburgh, Pa.; Prof. H. A. Surface and Mr. V.A.E. Decke, Harrisburg, Pa.; Prof. Mel. T. Cook, Newark, Del. ; Prof. Franklin Sherman and Mr. Z. P. Metcalf, Raleigh, N.C.; Prof. A. F. Conradi, Clemson College, 5S. C.; Mr. E. C. Cotton, Knoxville, Tenn.; 5 6 LEAFHOPPERS AFFECTING CEREALS, ETC. Prof. H. Garman, Lexington, Ky.; Mr. Harper Dean, San Antonio, Tex.; Prof. S. M. Tracy, Biloxi, Miss.; Mr. D. L. Van Dine, New Orleans, La.; Prof. A. E. Vinson and Dr. D. T. McDougall, of Tuc- son, Ariz.; Profs. C. W. Woodworth and W. B. Herms and Mr. Chas. Fuchs, at Berkeley, Cal.; Profs. E. D. Ball and E. G. Titus, at Logan, Utah; Prof. C. P. Gillette, Fort Collins, Colo.; Profs. T. J. Headlee and G. A. Dean, at Manhattan, Kans.; and Prof. S. J. Hunter, Lawrence, Kans. The collections at Cornell University, the Carnegie Museum, the Illinois State Laboratory of Natural History, Iowa State College (Ames, Iowa), the American Museum of Natural History (New York), the Boston Society of Natural History at Boston, the New Hampshire Agricultural College, the Bureau of Entomology, and the National Museum, as well as the private collections of many individuals, especially those of Mr. E. P. Van Duzee and Dr. E. D. Ball, have been freely at my disposal and have yielded many records of value. A large number of the drawings have been made by the skillful hand of Miss Charlotte King, of Ames, Iowa; and some others, also of her drawing at an earlier period, have been used from the Iowa Experiment Station bulletins with the kind consent of the station oflicers. EO: CONTENTS: Pure MeMROtear see ccc a2. 2 SARE IL EN Rayer el) TL aott APG Peoperor the present. investigation... 2:2<.=.2..2-2225/20ccc2220) 8.20292... Mamie rna extent Ob injumy. 5. ..4- ot eve dzsgiseaa was ce. box SS Bee EieteGere 32828 aol Pie. Pecks dee dee nsw a eka hs de LPR OOS LL, Derivation of our leaihopper faunas. v. ly. 2a) 292.2 kk So eS Species principally concerned in destructive attacks...............2..22..-.. Reeterie MD itshok Steele See cle 68 owl Shee yda es es Does secs EO. Sie ea ONe RT EMC hs yettiest «Foes tee te ee ade Od es CAP er eee La OviSe merc ni oe kisses Sede te hee shea eld 2a oe SL. fe Nunr eMAMINe ae AY ea hoe ne se case tae nel el DU Se ial See eee 2 Evidence as to the relation of birds to leafhoppers..........-......- Repilesandbattachians. i. t2.222, 2.20 eines Se Le eee ImBeGieneMmLCses eri awn) ae aren bis at's ab se wa tnns D>. i ie Sens UO ea eeienak Lie0h omer See Ca. «chee ny A ERR, Capturing in hopperdozers or tar’ pans: ==). .24 2. b2s.2s<0 582) S ese: Spraying. perme pec rAOEWeCOLdy, OF INJUPY ooece. swe eae cea, = Satake 302 1, 022, 288 6 200 75 | 10] 8 7|40|0 6 BECOUUGLECOLG 2 3. foecas once cee sommes 285 727,640 | 13 | 125 80 | 25 | 4 10 | 15] 3 10 Average of two counts.....-..--..-- 318 874,964 | 10} 163 78) 18} 6] 8] 28) 13 8 Oct. 13:2 IDES et) (0 ee ee Se eee ee 370 | 1,174,480 | 10} 200 50 | 30 }15 | 20} 30] 5 10 HECOMMMTOCOL Monet snes ce sesccc ence = 571 | 1,658,184 | 10] 385 30 | 35 |20 | 18] 40] 8 25 Average of two counts...........--. 471 1,416,332 | 10 | 292 40 | 33 |17 | 19 | 35 | 6 18 Oct. 18:3 tank fT Pare Da to TOTES TES (0) 0 Dee BEES Dee eee co ae ete 748 | 2,172,192 | 15 | 596 2/174] 0 2 | 19 |36 4 BECOHUMeCOLOGcser sendin ore soe. 538 1, 562,352 | 10 425 515010 3 | 25 |20 0 ABPOCONG = fa Sec euice tebe jaece age 653 1,896, 312 | 20 | 500 1 }100 | 0 5 | 15 110 2 Average of three counts.........--- 646 | 1,876,952 | 15 | 507 3175] 0 3 | 19 |22 2 Oct. 25 (cool day): 4 DIrSinOCOMMee sa ace cence costes te 354 | 1,028,016 | 25 | 300 0} 20) 0 Ol 'S170 1 Second record --| 418] 1,218,872] 10} 356 2{| 45/1 0; 01,0 4 pninGereCOlLW ence canes eas core scee ce 303 879,912 | 30} 250 0/10) 0 oP Gee 2 Average of three counts.........--- 358 | 1,040,600 | 22 | 302 20 | Pe (PeeeS: | eee 2 | 1 Lowland timothy, fairly short. 3 Upland timothy, grass eaten short. 2 Timothy and bluegrass, Ohio State University Farm. 4 Upland timothy, grass fairly short. CROPS AFFECTED. While our survey is intended to cover the various cereals and forage crops, it must for a number of reasons be more complete for those that are of most general culture. In general, it may be stated that all of the crops belonging to the grass family and most of those in general cultivation belonging to the legumes are infested by one or another, often by many, species of the leafhoppers. The abundance and corresponding injury vary greatly with these crops for different parts of the country and under different cultural conditions, as also with different seasons, so much so that general statements for annual crops are hardly applicable here. One of the most obvious conditions, however, is that the greatest drain occurs where, owing to continuity of crops or by close association of common food plants, there is offered an exceptional opportunity for the survival and increase of the insects from generation to generation through a season or during a series of years. For the wheat, oats, rye, and barley crops the most important species are, in the North and Northwest, Cicadula 6-notata and Athysanus exitiosus, and in the South, A. exitiosus and Dreculacephala 29460°—Bull. 108—12——2 16 LEAFHOPPERS AFFECTING CEREALS, ETC. reticulata. For the grass crop, including timothy, brome grass, and bluegrass, the most important species are Deltocephalus inimicus, D. affinis, D. configuratus, Dreculacephala mollipes, and Phlepsius irroratus. For clover, alsike, alfalfa, soy beans, and leguminous crops the most important are Agallia sanguinolenta and Empoasca mali. The fact that in many parts of the country their injury is negligible for such crops as wheat, oats, rye, etc., is due to the rotation or alter- nation of crops in such manner as to make their rapid increase impos- sible. On the other hand, the conditions existing in permanent pastures and meadows or that prevail where wheat, oats, etc., are grown closely adjacent to considerable areas of permanent grassland furnish favorable opportunity for their multiplication and migration, and serious injury must inevitably follow. One of the strongest contrasts in this line is furnished by the methods of wheat culture in the North and South. Throughout most of the spring-wheat section of the Northwest and the winter-wheat section of the northeastern United States the complete system of rotation or the absence of adjacent grass areas at the time when wheat fields could be infested renders injury from these insects almost unknown. In a number ef the Southern States, however, the abundance of the grasses adjacent or the overlapping of the seasons permits a serious autumn infestation of the fields of winter wheat, rye, and oats and a consequent annual loss from this source. This is especially true of the Piedmont Plateau in South Carolina and Georgia, where the prevailing practice of ter- racing (see Pl. II, fig. 3) to prevent washing of the hillsides results in permanent strips of uncultivated and permanent grassland, including a mixture of many kinds of useless weeds. Furthermore, the size of the fields must be an important factor in the extent of infestation from adjacent fields and consequent injury. Where the fields cover hundreds or thousands of acres, opportunity for infestation is far less than where they cover but a few acres and are interspersed with permanent grasslands. In the extensive stock-grazing regions of the central-western and northwestern United States where there are extensive permanent pastures, and notably the great area of wild grazing land (see Pl. III, fig. 1), both prairie and woodland, these insects have the best opportunity for production of successive generations each season and their number is limited only by the ability of the plants to sustain them or by the control affected by natural enemies, such as the para- sitic or predaceous insects, spiders, birds, etc., that feed upon them. DERIVATION OF OUR LEAFHOPPER FAUNA. Inasmuch as several economic problems are dependent on a knowl- edge of the source of our present leafhopper fauna, it is desirable that this matter should be touched upon, although it must be admitted DERIVATION OF OUR LEAFHOPPER FAUNA. £7 that we are far from having sufficient data to warrant very positive conclusions. Nevertheless, the known facts concerning a number of the genera or subfamilies seem to point in certain directions and a cursory review of these would seem in place. If we compare, in a very general survey, the American with European or Asiatic leaf- hopper groups, we are perhaps first struck with numerous funda- mental similarities, and, second, with the comparatively few cases in which there seems to be specific identity; a condition which would indicate common origin for the groups in general, and, further, a common development through a long period with a separation only long enough to result in the minor separations of species. While migrations may account for some of the agreements, there are many in which such explanation seems unwarranted—and we have a few cases in which a comparatively recent introduction seems quite certain. In the genus Deltocephalus, which is practically of world-wide dis- tribution, a comparison two decades ago might have led one to believe the genus essentially European, as more than a half hundred species are listed there. But within the last 20 years species for North America have been discovered and described in large numbers until now there are nearly a hundred known from the United States alone, a number which far outweighs the European showing and, if judged by number of species, we will be obliged to consider America as the home of the group and postulate a distribution from here to other geographic regions. Certainly the immense variety of forms with their wide range in latitude and altitude must be accepted as evi- dence of great antiquity. A great many of the species are boreal or alpine in distribution and while perhaps some allowance should be made for more extended collection and study in the North, it appears evident that the center of abundance and of variety of adaptation is to be found in the plain and plateau region of the Mississippi Valley and among the Rocky Mountains. From such a center the species diminish in number to the southward, few being known from Central America and South America. Dispersal then may have proceeded by northward routes to Europe and Asia, and southward through Central America and into South America. As for the spe- cies which have a common distribution in America and Europe it is as easy to assume migration from America to Europe as the reverse. Deltocephalus abdominalis Fab. and D. minki ¥ ieb., which occur in northern Europe and America, may thus have uprated in one direction or the other, but our D. debilis Uhl., which may be a deriva tive from abdominalis, has apparently had its origin in this country. In rather striking contrast to the Deltocephalus group we may take the genus Agallia, which, with some 25 or 30 species for America, shows a strong ppapunder thc both in number of species and adapta- tion for environment in the southern United States and especially 18 LEAFHOPPERS AFFECTING CEREALS, BTC. in Mexico, Central America, and the West Indies. If we note the bare half-dozen species known in Europe, and the further fact that nearly all the species drop off as we pass northward in either region, we can best incline to the belief that this genus is essentially tropical or at least subtropical in its origin and that its dispersal has been northward into the northern United States and Canada and probably by an African route into southern Europe. If such be the case, it is interesting to note that a separation into certain types within the genus must have occurred before the migration, as the Kuropean species Agallia venosa Fall. and A. puncticeps Germ. parallel very nicely our groups of which Agallia sanguinolenta and A. 4-punctata Prov. are typical examples. Such a derivation possesses peculiar sig- nificance in connection with certain habits and life-history features, especially in modes of hibernation, and some of these may prove of fundamental importance in connection with efforts toward practical control. Again, we have in Athysanus exitiosus Uhl. a species which has in all probability spread over the United States in very recent times, possibly even within the last half century, and which almost cer- tainly had its dispersal from a tropical or subtropical center. Another similar case, discussed more fully in another place, is found in Dreculacephala reticulata Sign., which is even now probably working gradually northward, though it seems from its present dis- tribution to have a pretty definite climatic restriction. SPECIES PRINCIPALLY CONCERNED IN DESTRUCTIVE ATTACKS. Serious outbreaks upon different cereal crops are to be charged to a few species, notably Deltocephalus inimicus, D. nigrifrons, Cica- dula 6-notata, Dreculacephala reticulata, D. mollipes, Athysanus exi- tiosus, and Phlepsius irroratus, all of which are among the most important from an economic point of view. There are numerous other species which attack these crops, especially various grasses and forage crops, the habits of which are important, but whose injuries individually are of less consequence than for the species just cited. In the case of the wheat crop serious attacks in America are to be charged against the few species above mentioned, all of which, except one, are native to this country; hence, not original wheat-feeding species. They seem, however, to find this plant an attractive food and where conditions permit will gather upon it in very destructive numbers and cause serious injury. Comparatively speaking, very few of the old-world species in this group have fol- lowed the wheat plant to this country, and there is only one species common to both Europe and America that can be considered a pest. Whether this species has been introduced since the introduction of wheat in this country is a question that probably can not be deter- mined, since it is now so widely distributed that there is little evi- GENERAL HABITS. 19 dence pointing to the trend of its distribution. (See discussion under Cicadula 6-notata, pp. 97-99.) It is extremely probable that some of the native species that occur in moderate numbers on various native plants have been stim- ulated by the introduction of cultivated crops which have furnished them a fresh food supply, so that they have increased greatly in num- bers and have become of more importance from an economic stand- point than would have been true in their connection with native plants. Most of our species, especially those that attack cultivated crops, have a wide range of food plants. Some, however, are re- stricted very closely to certain genera or species of plants as hosts. GENERAL HABITS. There are several features in the general habits of these insects which may be discussed together, although there are certain ones in which each particular species must be considered by itself. In their food habits, as has been mentioned, there is a wide diversity, some species affecting a great variety of plants, others a very few. The various species, however, agree pretty generally in attacking the leaves or the freshly grown portions of the stem of the plant, making their punctures where they can secure the sap with the greatest ease, thus affecting the growth of the more succulent portions. In many in- stances the insect shows a distinct adaptation to certain parts of the plant, so that the shape and color of the body blends in with the part upon which it is feeding. This is the most noticeable in the case of certain species which are marked so that the colors blend with certain portions of the plant, notably in cases where this coincides with the markings at the joints of the stems, instances being known where such blending causes the most perfect resemblance of the insect to the jomt. Some of the insects affect the seeds or blossoms, others cluster near the ground, and some have even been reported as affecting the roots, but this must be exceptional as very few have been noted to attack the plant in this manner. There is no distinct adherence to a particular plant except durmg the nymphal stages or for certain species which have aborted wings and are therefore unable to fly; practically all the species, however, jump with great facility and if disturbed will leave the plant and come to rest either on the ground or some adjacent plant. General migration of the insects is not common, but there must be local migrations from field to field, especially at times when the food supply becomes scarce or unsuitable on account of the ripening of the plant. Atsuch times we may have a general dispersal of the insects; for instance, from wheat fields to adjacent grasslands, or in autumn from grasslands to adjacent fields of fall wheat, oats, rye, ete., which furnish a much more attractive food for that season. Migrations in 20 LEAFHOPPERS AFFECTING CEREALS, ETC. any wide sense are unknown for any of the species. There has been observed in many cases a distinct tendency to gather at night around conspicuous lights, and while it is not known whether all of the species are thus attracted, so many different ones have been noted as being attracted by artificial lights that we may fairly presume that the habit is quite general. An instance was reported to the writer by Prof. Stedman, formerly of Missouri, with accompanying specimens of Dreculacephala mollipes, to the effect that this species gathered about lights at Columbia, Mo., in such numbers that they could be gathered up by the bushel. We have noted many instances of the appearance of the various species, including practically all of the more common, in rooms which are brilliantly lighted. This habit is sufficiently pro- nounced that it may be utilized for the purpose of collecting and destroying the adults before they have deposited eggs, although it has not been experimented upon to such an extent as to warrant any conclusion. An interesting case of the assembling of these insects at Urbana, Ill., has been reported to me by my son, H.T. Osborn. He states that on the evenings of October 9 and 10, 1909, he noticed a cloud of insects about a cottonwood tree and upon examination found that these consisted largely of the Phlepswus vrroratus. These were so numerous that he caught a net full, but no evidence of egg-depositing or of a particular object in this assembling was noticed. The winter condition of these species varies, some of them passing the colder months as adults and in these egg-laying occurs in early spring; others hibernate as partially grown nymphs; and in other species, particularly the grass-infesting forms, hibernation is appar- ently common in the egg stage. This matter of hibernation is of the greatest importance, especially in connection with methods of control based on the treatment that is possible in late autumn and in early spring. It also is related to the effects of climate, as in the case of those forms which become active in mild weather during winter and are thus exposed to conditions which may affect their survival and the consequent injuries the following season. Another general habit which is of importance is a tendency to dispersal from one kind of plant to another during the last nymphal stage. It has been noticed that many species which seem to be very closely restricted "to partic- ular plants in the earlier nymphal stages, during the last nymphal stage scatter freely to different kinds of plants, showing a distinct disposition to vary their diet. LIFE HISTORY IN GENERAL. All of the species of leafhoppers pass through a series of molts, usually four or five in number, and in these various stages they show a gradual progression toward the adult form. In some cases these : LIFE HISTORY IN GENERAL. a4 early forms are sufficiently like the later and adult stages to be recog- nized, but more commonly there is sufficient difference in their appear- ance so that it is only by rearing them from stage to stage or by care- ful comparison of the different stages that it is possible to make out the correct life history. All, of course, pass through the egg and larval stages, and the last nymphal stage may be considered as correspond- ing to the pupal stage of insects in general. So far as has been deter- mined the eggs in the species affecting grains and grasses are deposited in the leaves or stems of the food plants of the larve. The method of deposition has not been accurately noted in very many instances, but, for such as have been observed, it consists in the pushing of the eggs by means of the strong ovipositor into the margin of the leaf or into the spaces between the leaf and the stem so that the eggs are protected either by a covering of epidermis or by the thin leaf-sheath surround- ing the stem. A good example of the method of egg deposition is found in the case of the shovel-nosed leafhopper, which is figured on page 66. The number of eggs deposited by an individual is known in a few cases and probably varies with different species. In some cases it must be considerable, as the rate of multiplication is rapid. The hatching of the eggs takes place either in a few days after the deposi- tion or, in the case of hibernating eggs, early in the following spring, and consists simply in the emergence of the larve, the eggs being broken open at the end nearest the opening into which the egg has been forced. The molting occurs at uniform periods and consists in the shedding of the entire epidermal covering, this usually remaining attached to the surface of the plant as a thin, transparent film. The insects increase in size and soon change from the light color of recent emergence to the dark intense color common to the species. The number of generations in each season is also a variable matter, but there are commonly two generations each season, in some probably three, and in a few it is known that a single generation occurs. This is, of course, an important factor in the economic importance of the species since each additional generation provides for an immense increase of the numbers of individuals and also makes the special conditions of culture for the crop on which it feeds much less effective. ECOLOGIC RELATIONS. The leafhoppers constitute one element in a very complex relation of plants and animals, including birds, mammals, reptiles, toads, insects, spiders, etc., and it is only by the recognition of this relation that we can offer any very adequate explanation of their proper place in nature, and of their importance in the economy of cultivation. Primarily they are associated with certain kinds of plants upon which they depend for their sustenance, and the abundance of leafhoppers will be affected, necessarily, by the abundance of the food plant and 22 LEAFHOPPERS AFFECTING CEREALS, ETC. - its availability as food material. An undue increase of the leaf- hoppers, which should result in the diminution of the food supply, must necessarily affect the possibilities of multiplication and cause a certain reduction in the number of the insects. This is, however, by no means the only statement of conditions as, aside from these two forms which may be associated in the same area, a large number of other organisms, both plant and animal, will affect. the problem. The occurrence of different birds and predaceous insects which prey upon the leafhoppers will naturally reduce their numbers and to that extent favor the plants which serve as their food, whereas the pres- ence of herbivorous animals, grasshoppers, cutworms, etc., serves to reduce the available food supply. Aside from these dominant forms there are also various fungus parasites which attack both insects and plants and which play their part in the complex of which the leaf- hoppers are such a conspicuous element. Furthermore the minute insect parasites which attack the leafhoppers add their part, tending to keep the latter reduced in numbers. The relation of these and other direct parasites which concern them may be considered under the general head of natural enemies. NATURAL ENEMIES. That leafhoppers maintain a fairly average abundance from year to year, for the most part causing no perceptible devastation, is due to the fact that there are so many different natural agencies tending to reduce their numbers or to keep them in check. Of these natural enemies birds, spiders, and predaceous and parasitic insects are probably the most important and require careful consideration. It seems improbable that leafhoppers are affected to any great extent by mammals, except as eggs may be swallowed by foraging species— cattle, sheep, ete. The only forms which would seem likely to feed upon them are the moles and these confine their work so largely beneath the surface of the ground that it is doubtful if they would secure many of the leafhoppers. There are ne records to show any service in this direction. Birps. Birds would undoubtedly be thought of as an important factor in the natural control of leafhoppers. It would seem that they might feed very commonly upon these insects; and yet very little has been published in the way of correct determination or definite records of the kinds of birds which feed upon them, or the extent to which these leafhoppers enter into their normal food. The most complete records in this line are those accumulated by the Bureau of Biological Survey of the Department of Agriculture, which has for many years past been making a record of the contents of birds’ stomachs. Besides the NATURAL ENEMIES: BIRDS. ao published data concerning certain species of birds, that bureau has an immense collection of unpublished records and these have been very kindly put at my disposal for the purpose of this study. Practi- cally all of the data here presented on this point were derived from this material. While these records do not, in most cases, give the particular kind of leafhopper which is fed upon by certain species of birds, it should represent, of course, the kinds of leafhoppers which were abundant at the time and place indicated. The birds, of course, make no discrimination between species, except as they might appear in numbers or prove an easier prey. EVIDENCE AS TO THE RELATION OF BIRDS TO LEAFHOPPERS. While at first thought we might consider birds as a most important element in control of these insects, a closer study reveals many reasons why they must depend upon them but little as a food supply. Even with this more conservative view in mind, however, the actual con- dition as represented by the records of the Biological Survey are rather disappointing since they show that for practically all of our common birds the leafhoppers constitute so small a portion of their food supply that birds very properly may be considered as almost negligible in any consideration of the natural agencies of control. It is, however, important, both as a matter of record and for the benefit of future workers, that the actual condition as indicated by these records should be made available, and I have endeavored to sum up, as briefly as possible, the results of an analysis of the figures obtained, and the table of records is appended. According to the records consulted by me and later revised by the Biological Survey, there are 119 different species of birds among those examined by that bureau whose stomachs contained jassid remains in various proportions, from a trace to 80 per cent. But, putting all the stomachs together, we have only 770 which contained jassid material out of a total of some 47,000 stomachs examined, or less than one out of fifty. Even for the species of birds showing jassids in their food, we have only 770 out of about 28,000 (about 1 in 40) stomachs which ineluded jassid remains and for a large majority of these stomachs examined the jassid contents were but from 1 to 10 per cent, so that on a most liberal estimate we can claim about the thousandth part of the food of birds as being made up of leafhoppers. However, this general average may not represent the actual con- dition of effectiveness, for some of our most common birds abound in pastures and meadows where leafhoppers occur, and a critical examination for such species is desirable. In the first place we may eliminate practically all the waterfowl— loons, divers, gulls, terns, pelicans, ducks, geese, cranes, bitterns, 24 LEAFHOPPERS AFFECTING CEREALS, ETC. herons, ete.—since they usually frequent places where these insects are not abundant, A few records occur for snipe and sandpiper and one for the spotted sandpiper indicating that this latter bird may feed quite extensively on leafhoppers—probably species occurring on grasses in marshy ground. Of the grouse family, the habits of which would seem to make them fitted to secure some portion of jassid food, only a very few records show such diet. Out of 75 prairie chickens, now no longer a factor except for the plains region, only one had eaten jassids; but the one taken on a Nebraska prairie in October had jassid material for 40 per cent of its stomach contents. This would show distinct ability to feed on these insects when available. For the common quail or bobwhite, whose wide distribution and frequent abundance make it perhaps of greater interest for this family, out of 971 stomachs only 35 con- tained jassid fragments, and for these they constituted only a very small percentage of the food, usually from 1 to 7 per cent. What the quail might do, however, in the case of an abundance of material of the larger species is shown in a series of stomachs from Virginia, taken in autumn, which included numbers of Oncometopia lateralis. For the partridge (Bonasa umbellus), one bird out of 423 had eaten one leafhopper (a tettigonid) or 1 per cent—a food ratio for the species of 1 to 42,300, but so far as open fields are concerned this bird is naturally not to be considered of importance. We would not expect the larger birds of prey, hawks, owls, etc., to feed at all on such small insects, so it may be considered merely accidental that the Cooper’s hawk, one bird out of 109, had eaten a froghopper (a cercopid), which constituted one-twentieth of its stomach contents. Possibly, too, this was contained in the stomach of some other animal eaten by the hawk and, being less easily disintegrated in the process of digestion, remained as a fragment in the stomach. The woodpeckers certainly would not be expected to prey on these insects, and for only one species, the downy woodpecker (Dryobates pubescens), is there any record, and that for only two birds out of 750. Stomachs of Allen’s humming bird, of the Pacific coast, show a record of 1 in 3 with 22 per cent jassid food; but this is offset by 88 per cent of spiders, which would suggest that the jassids were secured when in the grasp of spiders; another western hummer, Calypte anna, shows 10 in 111. The nighthawk is distinctly msectivorous and as jassids are more or less on the wing at night these would seem open to attack, but the record shows only 22 birds out of 250 to have fed on them and the ratio of these to other insects to be very small. One or two excep- tional cases would indicate captures during some extensive flight of jassids. - NATURAL ENEMIES: BIRDS. 95 The chimney swift, a distinctly insectitvorous bird, shows 13 out of 139 to have eaten leafhoppers, but one of these showed 50 per cent jassid material. The flycatchers, which are preeminently insect feeders and active in the meadows and pastures, show, nevertheless, a very small leaf- hopper diet. The best record is for a California species (Hmpidonax difficilis) for which 11 birds in a total of 148 had eaten leafhoppers and in proportions as high as 73 per cent. Among our eastern species, only 3 birds in 91 of the yellow-bellied flycatcher (Hmpidonax flaviventris) had eaten leafhoppers, and in the proportion of 3 to 15 per cent. Traill’s flyeatcher (Empidonaz trailli) shows 5 in 134 with proportion for these up to 10 per cent, the Acadian flycatcher (/. virescens), 3 in 93 with 10 per cent for two, and least flycatcher (/. minimus), 4 in 162 with 10 per cent of jassid material in two and 20 per cent in one. The record for these four eastern flycatchers which might be expected to be especially serviceable shows, therefore, all together only 15 out of 480 stomachs to include jassid material, and the average for these can not be estimated as more than 10 per cent, so that the ratio of jassid diet would be only 1 to 500, or one-fifth of 1 per cent. The best that can be claimed for them, therefore, is that in case of excessive numbers of leafhoppers they might help a little in their destruction. Even less useful in this connection are the phoebe and pewee, showing only about 2 to 100 with jassid contents, though two stom- achs contained, one, 88 per cent, and another 100 per cent. The common kingbird, so universally present in fields, shows still less, 6 in 634, one bird, however, showing 52 per cent. One of the best showings is made by a California species, Myiarchus cinerascens, for which 7 out of 90 birds had eaten jassids and in proportions as high as 94 per cent, while the eastern crested flycatcher (Myiarchus crinitus) shows again only 3 in 244 and a proportion of 5, 15, and 50 per cent. Among the family of orioles and blackbirds, the cowbird shows the best record as a jassid feeder, there being 25 stomachs out of 590 with jassid contents, and for these 25 the proportion varies from a trace to 61 per cent, the average percentage for the 25 stomachs being 18.5 per cent—a food ratio of approximately 1 to 128; that is to say, 1 bird out of every 23 had eaten jassids to the extent of nearly one- fifth of his bill of fare. It is fair to assume that many of the birds showing no jassid diet were taken at times or places where this food was not available, and on this basis we can fairly credit the cowbird with good service—the best apparently of any of the birds for which data have been examined except the sharp-tailed sparrow. The California redwing (Agelaius gubernator) shows a quite excel- lent record of 12 to 200, but our eastern species (Agelaius pheniceus) 26 LEAFHOPPERS AFFECTING CEREALS, ETC. only 7 in 1,150; the purple grackle or crow blackbird (Quiscalus quiscula) only 10 in 2,384, and these either but a trace or very small percentage, and the common meadowlark, a most familiar field resi- dent, shows no record at all of eating Jasside, but two birds out of 1,157 had eaten cercopids to the extent of 5 per cent and 2 per cent, The Baltimore oriole (/cterus galbula) gives 1 in 207, but this one con- tained 88 per cent jassids. The orchard oriole (Jeterus spurius) 3 in 153, and the Bullock’s oriole (Icterus bullock) 6 in 293. In the sparrow family there are many species which from constant occurrence in fields have a distinct interest in this connection. While primarily seed feeding, it is known that many of them frequently include insects in their diet. None of the stomachs, however, except possibly the sharp-tailed sparrow, shows a suflicient amount of jassids to indicate that the members of this family are of any consequence as a check for these pests. The lark sparrow shows only 5 in 257 and very small percentages in these five; the sharp-tailed sparrow 4 in 44, and Passerherbulus maritimus 2 in 31; the swamp sparrow, 2 in 72; the Lincoln spar- row, 4 in 42, and the common song sparrow, 12 in 714; the savanna sparrow, 3 in 300; the spotted bunting (Pipilo m. montanus) 2 in 150; the vesper sparrow, 2 in 140; the field sparrow 4 in 240, and the tree sparrow 2 in 555. The field sparrow shows 4 in 250, but these four are high, two being credited with 100 per cent jassids. The sharp-tailed sparrow, with 4 birds out of 44, shows percentages of 80, 80, 75, and 30, or an average for the four of 662 per cent, or a ratio for the 44 birds of 1 to 17, or 6 per cent jassid food, which is the highest percentage we have noted for any species and shows no records of spiders eaten. The next best of these records, 4 in 42 or 1 in every 104 for the Lincoln sparrow, with percentages of 4, 15, and 24, applies to one of the less common birds, and when the proportion of jassid mate- rial is noted gives us only 1 to 100 as the real ratio of leafhopper food _to be credited to this bird. : Two of the swallows, the violet-green swallow and the bank swallow, show considerable numbers, but these are doubtless from eases of unusual flight. The good record of the marsh wren is offset by the fact that it must be of little service except in swampy places, but the Bewick wren, if a more common bird, would make a very good showing. One of the nuthatches, Sitta pygmexa, as will be seen by the table, has a very striking record of 18 stomachs out of 32 birds with several containing 100 per cent of cercopids, but this is a Pacific Coast species and the tree-feeding habits of the bird exclude it from any probable service in grass or grain fields. It is clear, if any conclusions at all are warranted from the mass of evidence here available, that it is useless to depend on birds for NATURAL ENEMIES: BIRDS. OF control of these insects. No amount of “encouragement for the birds” or efforts to utilize their service in this direction can be expected to have any appreciable effect in reducing the number of leafhoppers, and we may dismiss this idea and turn our attention to other more hopeful agencies. It should be kept in mind distinctly that these conclusions refer only to the relation of birds to this particular class of insects and must not be used as an argument for or against the status of birds in relation to the control of insects in general or of any other group of pests. The writer is fully aware of the important service that is rendered by many of our common birds in the control of a number of serious insect pests and would by no means wish to contribute to any undervaluation of their service. The following list, with the leafhopper species arranged in alpha- betic order, shows the species of birds which have fed upon leaf- hoppers, the number of stomachs containing such material, with the total number of stomachs examined for each species and the per- centage for each record, as very kindly revised and corrected up to January 1, 1912, by the Biological Survey. Birds that have been found by stomach examination to have fed on leafhoppers,; the latter grouped by families. FULGORIDA. Ne ber pe, of stom- aes achs con- Name of bird. Name of insect. of stom- taining Percentages. achs ex- erm amined. family named. Chreturapelagiea 2.2.8... .......- Pulgoride): 20s et ere 137 2), aa Chordeiles virginianus.......-.--|.---- Ome ot ke setae wa caeee 266 4 | 2, trace, 1, 1. Otocorisialpesiris_= ..o_......2...|-4.- LO ye cy ee Sn ea “1,159 1/9. VITOR SnVORANAE 2. 2.2. eine LOS reales ee ante ee 74 Doleas Chordeiles virginianus........... Oliants anidus. 2.9252 es (*) 1 | 12 (12 spm.). Colinus virginianus............-- Scolops maculosus..........- 971 allie Lophortyx californicus.........-.- NCOLOPS SDenme beer ase ae 619 1 0: CERCOPIDA. Weeipiter COOPEr!.\-)..2--5-.---.-6 6. Cercopidieras eres ase 100 1 | Trace @hamisea fasciata-.=...-.-.......- Hateae DO Sire seed ee a 170 AD Make Geothlypis trichas............... joao COM Z E20 Set tLe 130 1°30: Tridoproene bicolor. .......-...... eaee? OOS Sae se ebay tan wee 164 1 | 10. Melospiza melodia................ Cereopidie (1 with 5 spm.).-- 718 3 | 15, 5, 100 Otocorisjalpestriss ) i 2... ..-- 2. @ercopidee ke oe sass eee Bes () 2 ales Quiscalus quiscula..............- (Soe = dons: feces : 2,384 tA ee Sturnella magna... .... Z 1,157 Pa ae Penthestes atricapillus. . ae 644 3 | 50, 79, 90 Polioptila ceerulea......-. tse dOu. 39 2 | 30, 20. Setophaga ruticilla............... EdOr wae 17 2 | 81, 50. SHIMON arth Soe oe a es 2 | COs seen 32 18 | 100, 88, 100, 20, 79, 83, 90, 100, 77, 25, 50,72, 45, 100,100, 100, 85, 65. Thryomanes bewicki.............|..-.- DO. Mtomee ner if 153 1 Gs Chordeiles virginianus........... | Aphrophora sp ( 1 | Trace Chordeiles virginianus........... | Clastoptera xanthocephala (‘) 2 | Trace, 1 (12 specimens. ) PUNCH AIKGHIUN 272.40. occ eck Ptyelusspeesoote-e ee 1 1 | 40. | 1 Number of stomachs recorded elsewhere in this list. 28 LEAFHOPPERS AFFECTING CEREALS, ETC. Birds that have been found by stomach examination to have fed on leafhoppers; the latter grouped by families—Continued. TETTIGONIDA. Number Total of stom- number eee Name of bird. Name of insect. of stom- | Sans Percentages. achs ex- | tsects amined. os the amily named. Hylocichlaeuttatal.. 2.2.2.0 Tettigonidweee..sscees ose 460 2 | 70, 5. Bonssatumbellus: $22. fost 2e Sees GORS ai ct AE Sees 423 1 | Trace Cardinalis cardinalis-..5 25-2... 5|22--- GOL SSIS ea See Oa 496 2 | 50, 12 Mylarchusicrinitus? ..as23ch sce. Pesce = Ok ssa8 Sas cS ESA 244 1 | 15. SAYOMNISipPROe We eye) 255 peewee |e (0 (0) eee Sete os ees 353 6 | 7, 25, 15, 6, 30, 25. Muscivora forficata.......-......- Aulacizes irrorata.......-2-: 128 1303 Chordeiles virginianus........... Dreculacephala reticulata. . () 1 | 9. Colinus! virginianus!.--.>522.) 2... Diedrocephala sp......:...- () Aa ted, ia Telmatodytes palustris...........|...-- GO ss Laat cs Sed a 59 alee Cheetura pelagica ....--.2.-----.- Diedrocephala versuta.....- (1) se pale Chordeiles virginianus..........-. Dreculacephala mollipes. .. (1) 5 | 6,10, 8, 1, 8. Chordeiles virginianus..........- Dreeculacephala reticulata. . () 1} 9. Cheetura pelagica........----..-- Dreculacephala sp......--- (1) Pa Wale aka): Chordeiles virginianus...........!....-. Clo EE PE eres Mea ee ae (1) 2 | 40, trace. Chordeiles virginianus........... Gypona octolineata......... () 1 | Trace. Chordeiles virginianus..........- Gypona sp. (1 with 12 spm.). (@) 2.| 2, trace. Pedicecetes phasianellus........- Helochara communis... ..... 52 15s Colinus virginianus.............- Homalodisea coagulata...... (1) 118) ee Colinus virginianus .............. Oncometopia lateralis. ....-. (4) il Trace, 6; 1, 5, 3, 2, 2, 4,5, 1, 3. Pedicecetes phasianellus........- ree lateralis (20 (1) Woe spm. Sayornis phoesbe:s: 2-225 s+ o-5-2!- Oncometopia lateralis... ..- (1) 2/ 61,8. Colinus Virginianus.............. Oncometopia'spy.-2 =... 4.2 - (@) 14 | 5,3, Es > ne irae 3, 5, , ? , ? ? 4. Sayornis phoebe..........- Mo See Oncometopia undata........ (!) 1 | 80. Empidonax trailli................ Tettigonia atropunctata. ___. 134 1] 4. Pedicecetes phasianellus.......-. Mettigonia:Spess. so -ceaseesee (@) 1 | 3. Chordeiles virginianus..........- Xerophloea viridis.........- (@) 6 erases 1, trace, race, 1. Planesticus migratorius..........|.-..- do Scktcte yo eee aes 1,126 1 BY THOSCOPIDA. Cheetura pelagica...........-...- Agallia 4-punctata.........- | (1) 4) 1,4,4,1 Otocorisialpestns she: 22 ne ED Dt “eT Aes aye! eA 30 carolinensis, enemy of. Jasside: 25... Seee os bse s 30 gambercenemy ok Jarside....22. eemotiwal ee 30 MUPERLENS, NEM Y Ol PAGO. - 20 cele No es pee Sn ai la ee 30 Perkinsiella saccharicida, insects, reared from leafhoppers, introduced to repress it - 33 the sugar-cane: leathopper. +25 .2sess.. 2 5 onc cee 51 Petrochelidon lunifrons, enemy of Jassidw..................- BM SAS Re 30 Pewee (see also Myiochanes virens). GHOtny: HULCAIMOM PONS 2 8 ier Wied Le ee Scie Se) detaate Sos eae ae 25 Lavippusaudan enemy OL leathoppers. << 2-2. 224.226 o4-+s ces ocusecsee eee 34 Sie THON Olean HOD DEES ac eras Syae y eee e o Ge eee 34 PUSH OME M Ve OU PCATNOPPOCES: 2 ooo). cican ese Kae van sees oan ea 34 Blilenus vilimeatus in: North Dakota in 1909. -..-.--....2-----+-+./2. if. eh eee eee aT 5 JST ie sede Re EE RITE a 30 Quail (see Bobwhite and Colinus virginianus). Guiscalus.quisenla, enemy of Cercopidee.. tapes. 2-5.) 2 eee. = ee 27 dgssidee. 2. . 2.24 bag b ke yscqatk ages tees eee 30 leathoppers: 25.2. seeks: ao ee see 25-26 iked-top. grass, food plant of ‘Cicadula 6-notata 1. eo. soe 2s ene ae eee 43 Deltocephalus. ajinis.— - - S222 228 ses 22s ose 43 UNUMUCUS = 28 6 eee ee 43,74 Thomnotennge Qenvinds - ie. ae ie eee 43 inedumolus ferus, enemy of leathoppers....-2. 0/4. =~ + 222 esac 2 ete 32 Redwing, California. (See Agelaius gubernator.) eastern. (See Agelaius pheniceus.) Regulus colendula, enemy Of Jasside. 2209-502 ass nen s+ See ee 30 satrapa, enemy of Jassides. 5 Sivoo d:k Lo kee gees eee eee eee 30 inepimles enemies of Léafhoppers re ac) Sas esis ees see Gt ee eee 31-32 Riparia riparia (see also Swallow, bank). enemy of Jaggidee.. oo. Sateen 94 oe Nee nek ee 30 ive, food plant. of Athysanius emitiosus.. 0... o.e 22 blew en ee eee eee 15, 90 Cicaditla’ 6-pUas 1... ao ss 2s eee dee ee ee 15, 99 Meliocemhalusvinumicus asa 2. soe eee 75 Drecuilacephata‘moliipes’ 2. 2.5 2. tanta eee = eee ae 57 TELLCULOIDS DEI ne oe Sane eee ee eee 15 Sandpiper, spotted (see also Actitis macularia). enemy of leafhoppers. . - - - - sgynghs Cig eh O20. SS oes eee 24 Savornis vigricans, enemy of Jassidee: |. yar tics Care ee nee 2 eee 30 pheebe (see also Phoebe). enemy of Tassie? 2 eae as gush at See een eee 30 Oncometopia lateralis.’ ..05.. = 3522 es as es eee 28 UNA = 15 3 be 2 Re 28 Tettigonidai.oci el Soko. 2 ee ee 28 gays; enemy of Jassidee: 22.53. o ose ntl. ge ee ee 30 Scolops maculosus, prey of Colinus virginianus......-...------------++------ Be sp., prey of Lophoriy® cahfornicus...-. 2. oe. once eer Pade eee See 27 Selasphorus alleni (see also Hummingbird, Allen’s). enemy olbWassidie >: 25s eA ce oe ee ee cee ee a eee 30 rufus, enemy Of Jassideer ..weweesesecceccusessencncs sigue sone 30 INDEX. 134 Page Setophaga ruticilla, enemy of Cercopide...... ............22. 20200 e eee eee 2 SS SR la ab ely MARDI a Pal ae ade fy 30 mau currucoides, enemy of. Jasside. = 2 22.2222. 029 PI 30 am. ocomentiis, enemy of Jasside. 2.2 SS 2S OE) oe 30 RAG) ORG OL ARSE Sl per 5% =! yt RE RE Oe ae 30 “Silver top” following attacks by leafhoppers and Thrips striatus. ..........-.- 13 Eee pygmied,.cnemy of Cercopide:. «2... 0S ee en DP see e TGs atk ete Sd A) 26 Soy beans, food plant of Agallia sanguinolenta...................22.2---2--- 16 EEE OMS T LE. meat are gece ores oe ee on eee 16, 44, 100, 101 Sparrow, field (see also Spizella pusilla). PMEMMY GigleMINGPPEIE Sel Se coc ge ote Se nn 5 sn eee ee eee 26 lark (see also Chondesies grammacus). Slibiny Gilexmmop persia. 6.- 6. fe. cs sealed Het Se 26 Lincoln (see also Melospiza lincolni). enemysenteathoppers... 2: =. .42-.:-- 2-2 ss sas soba goo 26 savanna (see also Passerculus sandwichensis). enpitty enleat hoppers...) 00 eect an’ ag yes = tee ae ee 26 sharp-tailed (see also Passerherbulus caudacutus). edemiy on lenthoppers so 2h o- es 2s 5 as win eee 26 song (see also Melospiza melodia). enemy Or liestheppers. 26 plan ore = cee ook es eee Laka 26 swamp (see also Melospiza georgiana). enemy Giledinnppeipe. sss sas a eo Ae oe 26 tree (see also Spizella monticola). enemy Omen NO pipers srereset Sac. se cee se gcse ee 26 vesper (see also Powcetes gramineus). Suey Or lentmoppers. \.32,.2- Sacco sae ee. bee nao. se oo ee 26 Spartina cynosuroides, food plant of Hecalus lineatus.......................-- 65 piers, cnemaca ot leafhoppettin.2/1..02-: 2.2. oset ss see. . ee ee ee 34-35 Spittle insects. (See Cercopide.) Spizella monticola (see also Sparrow, tree). CTO A BIMEE St. Make ercaer. cole a Reet oy ere ay oe ee 30 passerina, enemy of Jasside........___. Sys im sexi eee Mangan Sepa Vee ONT 2 30 pusilla (see also Sparrow, field). Gilemiy OF Fassia ne + ee meee 3 2S i Rn eichs Wn Re ee Agee 30 Sprayinpagainst Agailia sangwinolenta.-..- 2. ....2... 2.22.22 2.2--2-2--2ee 106 PATH SH AUS COOL LEE® <1 wR Tein awn Beta ok ote eee 94 Delioce puns: CHS =. ames as ts ok Koen ee cen hock 84 CON SPUF ANU ETE Oe os 2.08." wk eh ee 82 destructive leafhopper (Athysanus evitiosus)...... .....-.-- 90 DT XCUIACEDNGIE IRON ES = i sere eee ae one 628 os wank Coane 59 PT OAR CN TURE ort Stee oe et aos eee 103 ACI G CRON COMMUTE eee re eas oa oS oe ee 61 inimical leafhopper (Deltocephalus inimicus).... 2.2... ...-- 77 featinipperdin wemeriles see se. ee se a ee, ee 38 Say’s leafhopper (Deltocephalus sayi) ...............--.---- 86 Stelgidopteryx serripennis, enemy of leafhoppers...................---------.- 30 Sulcascepnala insArizona in 19102227224. 22 mbpch ocr 48 Stipa spartea, food plant of Parabolocratus viridis...................-.-.----. 68 Strepsiptera, species parasitic on leafhoppers....................-...-------. 33 Sturnella magna (see also Meadowlark). BREMY: OF CARCOMIMEey, ny ois-cn ace Pee co sons SSSR R We keeueme 27 122 LEAFHOPPERS AFFECTING CEREALS, ETC. Page Stunus vulgans, enemy of Jassutes 2022 2. . set tess ag seen tee 30 Swallow, bank (see also Riparia riparia). enemy of leafhoppers..: .-- 2.2.5). neues see eee - ae eee 26 violet-green (see also Tachycineta thalassina). enemy of leathoppers. <2... 2 seman oe ene eee 26 Swiit, chimney (see also Chetwra pelagica). enemy of leafhoppers. .............--.-. ae ee 25 Tachycineta thalassina (see also Swallow, violet-green). enemy of Jassidz....... BRE get ates ace es 5, 30 Tar pan. (See Hopperdozer.) Telmatodytes palustris (see also Wren, marsh). enemy of Diedrocephala:ep. 2 oe 2, eee ee eee 28 BEY 1101: ceiver Sa Ria enema MNS PI Sn I. 30 Tetragnatha laboriosa, enemy of leafhoppers..........---.---------+-+--++-+--- 34 Tettigonia atropunctata, prey of Empidonav trailli...........-.----2+--+-------- 28 bijide; seneral ACCOWnE ss os ake se ee eee ee 63 reticulata—Draculacephala reticulata, 2 22. as yes pee ne ae eee 53 Sp:, prey of Lars franklin... coo. sige seas cre ae eee 31 Ped upcetes PIVAStaNiCll tes «oe Sek kk ah AOU eg ML 28 eturonides bird enemies’. 455.1505 22 Sais eae ae ee on ee ee 28, 31 Thannotetlixc geminatus, ceneral-wecoumt. ¢ 2052505255 ae ee Ae ee 96-97 in Washington State im 1909) © < ag.) 7 er OW, : . yr wt . . OS er pois +e i) Ai hi tae ? ang . 0 Ae: hb) papi Mad ae "a Ad nie eee mo Oil Ip ak ae , Me 5 Ue att 4 fy fie Senay i. Seo f t iad at Seu, caeas rete aOR i a, Ate ivy ee poet 2 a y . . i an — 2th Sy fe Pies een at. 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