106 



THE AMEEICAN ENTOMOLOGIST. 



cous-Avhite pubescence. The larva resides in 

 the very heart of the gall, as with the other spe- 

 cies, but instead of the cocoon being thrice as 

 long as the body of the larva, it is scarcely at all 

 longer, and fits so closely that it is not a very easy 

 matter to remove it. In these two species, the 

 larva and pupa of one are absolutely undistin- 

 guishable from those of the other, and the perfect 

 flies resemble one another so closely that the 

 same figure answers equally well for both. 

 Their transformations also take place in the same 

 manner and very nearly at the same time; and 

 the galls attain tlieir full growth in the same 

 mouth of July. 



The Grape-Vise Apple-gall, ( Vitis po- 

 mum, new si^ecies,) Fig. 85 a. — In No. 2, page 

 28, and No. 3, page 64-, of the American Ento- 

 mologist, we referred to a "vegetable phenom- 

 enon" said to be found in Yirginia, in the form 

 of an applee-like growth from a grape-vine. The 

 prevailing opinion in that State seemed to be, 

 that it was a kind of hybrid fruit formed by the 

 union of a grape blossom with an apple 

 blossom. But wc intimated our opinion at 

 the time, that it was no fruit at ail, but 

 simply a gall produced by some unknown 

 species of gall gnat. We have since received 

 specimens of what is uudonbtedly the same 

 tiling, from two different sources, first from Mr. 

 B. L. Kingsbury of Alton, Illinois, and second 

 through the kindness of Mr. Stanfler, of Penn- 

 sylvania, from Thos. Moehan, the well known 

 editor of the Gardeners' Monthli/. Mr. Stauftcr 

 lias also favored us with a good colored figure of 

 one that he cut from the wild Frost Grape ( Vitis 

 rordifolia), August Dth, 1850, which agrees per- 

 fectly well with the two specimens in our pos- 

 session. Hence, after carefully examining these 

 specimens, wc can now announce with certainty 

 that this ''vegetable phenomenon"' is really what 

 wo originally inferred it to be — namely, a gall- 

 niadc by a gall gnat. Fig. 85 a, will give the reader 



Crplovs— (n) grecu, (b) yellow. 



a very good idea of this gall, and Fig. 85, b, of 

 its internal structure, showing the larvas that in- 

 h.abit its numerous cells, a single larva in a sin- 

 gle cell. All the galls that we have hitherto 



been treating of, have been what are technically 

 termed "raonathalamous" or "one-celled" galls, 

 inhabited by a single gall-making larva. But 

 this, as will be seen at once, is a "polythala- 

 mous" or many-celled gall, inhabited by a great 

 number of gall-making larvfe. 



As the fly that generates this gall will, in all 

 probability, not make its appearance until next 

 spring or summer, and as we have consequently 

 had, as yet, no opportunity to breed it ; it may 

 be very reasonably asked, how we know for cer- 

 tain that it will turn out to be some kind of Gall- 

 gnat ( Cecidomyia) ? AVe answer that the larvae of 

 all Gall-gnats are distinguishable at once from 

 other larva? by a peculiar process known as 

 the "breast-bone," and located on thelower sur- 

 face of the first joint of the breast. (See Fig. 86, 

 c.) Usually this "breast-bone" is of so dark a 

 color that it can be readily seen, even in a very 

 small larva, and its use apparently is to abrade 

 the surface upon which the larva lives and there- 

 by cause an abnormal flow of sap, which forms 

 the food of the little insect that is thus working 

 for its living. In Figure 8G, c, the head of the lar- 

 va is shown protruded ; biit all this group of larvie 

 have the power of retracting the head within the 

 body, so as to bring the "breast-bone" well into 

 play. In shape, this organ differs greatly, being 

 sometimes what we have called "clove-shaped," 

 as in Fig. 86, c, sometimes Y-shaped, as with 

 the larva3 of the two Willow-galls figured above, 

 and sometimes of other allied shapes. But in 

 every case there are several sharp prongs in front . 

 of it, adapted for wounding and piercing. As 

 a general rule, allied gall-gnats inhabiting the 

 same genus of plants have larv.-e with "breast- 

 bones" of the same, or a very similar shape. 

 For example, that of the larva to be next des- 

 cribed is absolutely undistinguisliable from that 

 of our larva; and so is that of Ihe larva of the 

 Pine-cone gall from that of the laiTa of the Cab- 

 bage-sprout gall.* 



Tn?: Grape-vine Filbekt-gali, ( Vitis cortj- 

 loidcs, new species). — We liavcmet with one or 



•For the satisfaction of the Bcieiititic reader, we annex des- 

 cviiitioiisoftlic aliovegsll iiufl of its Inrva, rlrswn tip from 

 the Alton .-iiecinit-n . 



Gall Vitis poMiM.— A snionth, fclobiilur, fleshy, fci'ass- 

 crrt-cn frail , 0,:iiJ iiioh in diani.tfr. attached by .1 rougli base.of 

 about (i. in inch in ilianiilir. like tlic base of a lia/.elnnt, to 

 the i-ane of tb.>Kra'.,--viii.-, It,, .xtrvnal surraco with aboni 

 eii,'bi in- nine longitmlincl sivi:c, dividins it into ciKht online 

 seK'meut,-., like tle.s. .Oa wauiimloii . Internally fleshy .ind 

 ofthe conBistrnce oi'll.f bull ..f a Halnlil l',,r one-ei.^'hth of its 

 diameter: then a ^eii- ..r • l^.n-M.-l .-..il.. di\ ideu each i nto 

 twocell»bvarepMlar,~eri-«"rtva.,s-,.T>ci.fnlili,.ns, tile lower 

 tier about 0.2 inch, tli.- ii|,]i. r li. r ali..iu n.:; ui.-li loiifc. t rom 

 center of one cell to that m' th.' aclj.iinin.t; cell is nearly 0.1 

 inch, and there are seven i.r .iulit cell, Mde by side. 



L.iRVA. -Bright yellow, nfihe normal ,haiie. Breast-bone 

 chestnut-brown, ofove-siiaped, the stem of the clove about 

 2* times as long as one of the anterior iirongs; tip ol tlie anal 

 joint ventralh- with two transversely arranged slender brown 

 spines, directed upwards and backwards, above which on 

 the dorsal lip is a tubercle. Probablyjunips by taking its tail 

 in its mouth, and if so belongs to the subgenus Dijilosis. 



i 



