298 



THE AMERICAN 



the insertion of tlie front wing . Antenna} {^ ^ usually as in 

 Figure 1, c § , / cj", 8-jointecl or g-jointcd (Sc+G+Cl. or Sc. 

 +7+(;i.) , with a club composed of two or three connate and 

 almost continent joints. Head and thorax very coarsely 

 punctate Abdomen as in Kgure 1, c ^, d g, 8-jointed, 

 polished, and compressed, especially §; the peduncle or 

 first joint sculptured, ^ about as long as the rest of the ab- 

 domen, $ short; f^ with the fourth joint, g with the fifth 

 joint very long and finely and closely punctate below. Stig- 

 ma (J' g simple. 



It is not very easy to see the sutures between tlie joints in 

 the antenna of ,^ Eunjtoma; but by examining a great num- 

 ber of (^(^, where the antennae were much convoluted, I 

 ascertained that the crook or elbow was always at the tip and 

 never at the base of any peduncle. Consequently, the real 

 suture is at the tip of every peduncle, as shown in the figure. 



Genus Decatoma. (Fig. 2, a g , & (^.) Body contractile 

 as in Eurytoma and with a similar groove for the middle 

 femora. Antenna3 (;^ g as in Figure 3, e § j ^ C?' C? "-joii^fed 

 (Sc.-}-5-fCl.) , filiform, the club slightly compressed, g 

 8-jointed CSc.+G-t-Ci.), gradually clavate, the club consider- ^ 

 ably compressed. Head and thorax very coarsely punctate. 

 Abdomen as in Figure 2, c J , <? |^, 8-jointed, polished, and 

 compressed, especially g ; peduncle sculx^tured, (^ not quite 

 as long as the rest of the abdomen, g ab6ut half as long; 

 (^ with the fourth joint, § with the flftli joint very long. 

 Stigma jj" $ thickened, widened and blackened. 



Gends Isosoma. (Fig, 3, 6 § ; fig. 4, a § , 6 jj" ) Body 

 not contractile and with no groove to receive the middle 

 femora. Antenn:c ^^ g as in Figure -t, e g,/,^, 9-jointed 

 (Sc.-l-7-l-Cl,), (5" liliforin and with joints 3-3 snbcqual in 

 lengtli, 5 gradually clavate, joints 2 and 4-8 all equally 

 short, 3 longer, 9 abont as long as 7 and 8 put together. 

 Head and thorax rather finely rugose. Abdomen as in 

 Figure 4, c g , li ^J, 8-jointed, polished, cylindrical, ^ with 

 the pednucle sirort and sculptui'ed, g almost scs.sile; (-^ witli 

 joints i and 5 long, g with joints 5 and 6 long. Stigma ^ g 

 simple . 



GENUS KURYTOMA. 

 Synoptical Table to find tlie species described below. 



A- Antcnnto f'emnle. 8-joiTiled (Sc. -|-0-|-Cl.) 



o. Head and tliomx pjirtly pale bicolor, n. sp. 



6. Head and thorax entirely black. 



1. IjeKH. incUidins coxa; and trochanters, en- ? 



tircly or almost entirely pale <, 



trace nnue with white hairs; abdomen ( prunieola, n. sp. 



tctnale buimcd with pale > • r 



*^''femak"ui"bbVf !'f™..';°!".:.'!';?.T.!';t aurieepB, n. sp. 



2. Le2s, except the bhick coxec, entirely pale, 



t Aiiteiiii:u tciiuile iinniial punetiventris, n. sp. 



** ^lonser'ilJncinh-.!'.'!!'. . ^".'!'.'. L^H"?]'. \ abnormleornis, „. sp. 



3. All coxa; blaclt , leniora and tibia; partly 1 



black, eacn successive pair more and > 



t Size large diastrophi, n. sp. 



ft Size aniall studiosa, Say. 



B. Antenna; female distinctly 0-Jointed (Sc-t-r-HCl.) gigantia, n. sp. 



Eurytoma bicolor, n, .sp.— (5"$ honej'-yellow. HcotZ sub- 

 opaque, conlluently and very coarsely punctate and witli 

 short whitish decumbent hairs; disk of occiput, and a .spot 

 enclosing the three ocelli and occasionally (1 f^) extending 

 in a salient angle nearly to the origin of the antenna^, but 

 usually expanded in tVoiit so as only to leave a more or less 

 wide pale orbit on each side, and usiially more or less widely 

 coiiHueiit behind with the occipital spot, all black. Antenntu 

 ii" 2 8-ji)iiitcd, fj" with no peduncle at the tip of joint 7 and 

 Joint S only ,>a longer than 7, g with joints 4-7 snbequal in 

 length; ^ g Avitli the scape lioney-yellow except at tip; 

 joint 2 glabrous, shining and black, the remaining joints 

 brown-black. Tltorax sculptured as the head, but still' more 

 coarsely antl with wliitish pubescence Collare sometimes 

 (1 1^) with only a dorsal black triangle, usually black on its 

 entire superior and partly on its lateral surface, the black 

 part occasionally (1 g) enclosing on each side a pale dot. 

 Mesothorax and metathorax above, except sometimes (I ^ 

 2 g) lor a small space above the wings, black. Abdomen 

 polished ane glabrous, but a little hairv towards its tip; 

 black (j", g black with the venter, and liiore or less of the 

 lower part of the dorsum, honey-yellow. Legs, iucluuing 

 coxiB and trochanters, honey-yellow, sometimes (1 (5" 1 $) 



immaculate, gener.ally with the femora and tibias, especially 

 g , more or less lightly tinged or vittate with dusky superi- 

 orly, each succeeding pair of legs more obviously so. Wincfs 

 hyaline; veins brownish-white, usually towards their tip 

 end ranging into brown-black Length ^ 0.11, g 0.08 — 

 0.11 inch. 



Described from 1 [^ 2 g bred June 3d, from a rough, 

 woody, snbglobular, black fnngoid swelling upon the twigs 

 of Black Oak, which is iufestetl by an undescribed Gall-fiy, 

 and which also occurs upon Red Oak, but in both cases 

 always very sijariugly and sparsely, and never In profnsion 

 and locally like tlie true Cynipidous gall , Q. podagra ["Walsh . 

 This fungoid growth is the supposed gall referred to by 

 OstenSacken in Proc. Ent. Soc. Phil. IV, p. 30.5, note. A 

 very similar but more elongate fungoid growth, which pro- 

 duces no G.all-fly whatever, but from which, as well as from 

 the Oak-fimgns, I have bred Trochilium hospes, Walsh, occurs 

 locally, but in the greatest profusion upon the Pig-nut Hick- 

 ory (Carya glabra). From this Ilickory-fungas, I have bred 

 the following Beetles : 1st, the r.are Chramerus icorice, Lee. 

 (Scolytidee) ; 2nd, a Magdalimis7 resembling at first sight M. 

 barbitus, Say, but structurally distinct, and 3d, a Cis which 

 according to LeConte is most probably C. pumicatus, Mellie. 

 I have no doubt that the Gall-fly obtained from the Oak- 

 fungus is inquilinous, as well as the uudistinguishable form 

 bred by Mr. Bassett from galls on the stem of some jfiant 

 supposed to be mustard. (Sec Osten Sacken, 1. c ) Not 

 improbably, the real g.all-maker of these mustard-galls was 

 some Gall- gnat {Cecidomyia). I shall have occasion ou a 

 subsequent iiage to quote sever.al cases, where gall-flies be- 

 longing to notoriously inquilinous genera are inquilinous in 

 Oecidomyidous galls. Authors have been sometimes a little 

 too apt to jump to the conclusion th.at, l:»ecause a particular 

 insect is bred from aiiarticular gall, therefore it is the author 

 of that g.all. No mode of reasoning can be more unsafe and 

 unsound. 



[Fig. 1.] 



Eurytoma prunieola, n. sp. (^ ^ (Fig. 1) Black. 

 Head subopaque, conlluently and very coarsely punctate, 

 and with short white declimbeiit hairs dense upon the 

 face. Ant.eiinte (f often distinctly 9-jointeil with joint 9 

 rufous, and always with a peduncle at tip of joint? but none 

 at tip of joint 8; in the same jj" one antenna is 8-jointed and 

 the other dislinctly 9-jointed: antennae g always 8-jointed, 

 ■\vitlt joints 4-7 subeqnal in length, and the club as long as 

 (i and 7 put together; ^^ g with the scape e.xcept sometimes 

 the extreme lip rufous, the other joints brown-black except 

 sometimes the 9th joint fj'. Thorax sculptured as the head 

 but still more coarsely, and with white pubescence. Abdo- 

 men polished and glabrous, but alittle hairy towards its tip; 

 (^ immaculate, g with tlie long medial or .'ilh joint always 

 rufous and the 4tn generally piceous. Legs, including eoxie 

 and troch.anters, honey-vellow or rufous ; the tarsi and 

 sometimes the tilda; vcv.^ii'ig on white. Wiiitis hyaline; veins 

 brownish-while, s;vncrallv shailing into brown or even 

 brown-black towaids Iheir tips. " Length (j" 0.11— 13, 

 g 0.10— 0.15 inch. 



Described from 12 ^J bred Tune 9th— 19th, a single ^ bred 

 August 23d, and 31 g bred .Tune 9th— July 1st, all from the 

 Cynipidous oak-gall Q. prunus, Walsh, of the preceding 

 year's growth. I observe in this species ot Eurytoma, as 



