THE AMEEICAN ENTOMOLOGI^ 



109 



the spring-, gapes open and allows the insects to 

 escape into the open air. When White Elmsare 

 planted as shade trees in large nnnibers in the I 

 neighborhood of houses, and become badly in- ; 

 tested by these galls, tlic winged flics tliat are j 

 generated in sucli myriads in the middk^ of sum- 

 mer often become a very serious miisance. Hence j 

 it is worth while for us to learn, that Avliensucli | 

 trees become large they will cease to be attack- i 

 cd in such manner.* 



Tliere may probably be some of our readers who 

 may be desirous of breeding the gall-making in- , 

 sects from (he galls figured above, or from such | 

 other galls as fliey may have Ijiemsclvcs discover- ■ 

 ed upon other plants. We would caution all such ! 

 persons not to be deceived by a very common i 

 phenomenon. Besides tlie true gall-maker, they j 

 will obtain from almost every gall, one or two, j 

 and sometimes one or U\o dozen perfectly dis- 

 tinct insects. Tliese will belong to two ditter- 

 cnt groups, and it will sometimes require some 

 considerable knowledge of entomology to dis- 

 tinguish them from the veritable authors of the 

 gall that is being experimented upon. The 

 groups above referred to may be catalogued as 

 follows : 



1st. Guest-insects, tomelimcs ver\- closely al- 

 lied to the gall-maker, sometimes as diftercnt as 

 it is possible to conceive. We Uaxc already, 

 under the head of the Pine-cone Willow-gall, 

 referred to a snnill Guest (Jall-gnat which dwells 

 under the leaves of (he Gall, without interfering 

 in any way witli (lie liealtli or prosperity of the 

 much larger Gall-gnat, that makes the gall and 

 lives in tlie very centre of it. ,So again in tlie 

 case of the Oak-apple of the Uhick Oak (Fig. 78). 

 There is a minute Gall-tly (Si/ix^rt/ns ht-rirenlris. 

 Osten Sackeii ) which is occasionally found in 

 considerable numbers in little cells located im- 

 mediately under the external rind of this Oak- 

 apple, where it lives in the larva slate upon (he 

 substance of tlie gall, without troublinsr, in anv 



•The Heel Elm, 



Ml lO 



• .Slipiieiv Kim. 

 ntiliui'il "i.hsc.r\ 

 IJut tlKic 



ll:ll 



IS tli,->" 



cockscojuli-llkc 



the upiMT lii.-f <>( H- l.-MVi", ii, small numlii-r-. a 'soliliivv iall 

 with quiti' !i Ihiii rinil. :ili..iir iiii inch loii^', -hiiiir.! nmoh 

 lilve iini- i.r tlins,.. (leiiirtiil in lij^niv Mi, uinl liilh.Tti. mi- 

 ilescril>c'il. It is imnk- bv ;i sprcics nlplanl Ic.nsi- Inl.mu im; 

 All ;h<- Siinu- Kcmis (Pi'mpliii/ui) n~ li:'. ss In Klinijic :l 



well kn<i\vn cim-KiiH (r/mrt is minlr h\ , lin-r -vnn, nl' 



' Vh\nt-\U-i- {lliirxoiniptd. HiiHiliiv = 7V/,«H.'if/-,(, llarlia). Su 

 thill on fill' same nc-'mis ol' tiv.-s, 'th.- Kim. \vi- have tliirc ilis- 

 linct t'ulls niacic hv tllr.-,- ,lisli;ii-t Kincra ..I' |ilant-lii-i'; tin- 

 moi-c •.'■•ncval nih- JH-iu- thai flic same -cnns ,>1' i;all-inakcr.s 

 Bltacks thi' same -cDvis „f j.laiits i he alc.vc ilcs.-ribcd 

 Kllll on the I{c,l Kim, \\ liicll \vc mav i-all the S|iinillc-shapeil 

 H;1iu-k:i1I (t'lmi fii.ini.), was lirst fir..lli.'lit to .aiv li.itice liv 

 i)l-. W M. Smith of N Y ; hut we have sinic h.nncl scMiiil 

 »|MTinicns in s.jufh niiuois. The w in-ial ins.ct {I'emiilnijiis 

 ulmi-J'usus, n s|i ). which milv mcasnivs (i iiT im-li to the tips 

 (■f till' wings, anil is of a iniilorm du-kv color, occiiiiv.l .lulv 

 nth. Out of is specimens, two have hotli wiiiu's. ami one "ii 

 sint'lc wint; vi-ineil preci.-elv like those of F.iwsuintr (h'ii; 70. 

 I-, p. ,s.')— tlius atVonlinL' a ■iniU'ticiil fxcmpliliciition of lio« 

 i.ni'Keinis,,fl>lant-lic.ennn -railiiallv in the eiiirse of iiiile- 

 lliiile iiL'is rjre into another 



wise, the much larger tenant of the central cell 

 (hat is the real gall-maker. From tliese little 

 cells it escapes early in the snmmer Ihrongh 

 small pin-holes, each of which opens into one of 

 the external cells; whereas the large hole (l''ig. 

 78, b), throngh which (he gall-maker escapes, 

 may be always (raced (o (he cend-al cell. In 

 bodi the above two cases the Guest-fly does not 

 molest the Gall-maker; and this is the more gen- 

 eral rule. But in cerlain odier cases the larva 

 of the Guest-fly, instead of living in a liouse of 

 his own. makes his way (o (he' house of the gall- 

 making larva, and alter having destroyed him, 

 takes possession of his tenement. Forextimple. 

 there is a large undescribed Guest (Jail-gnat"' 

 which, as we have clearly ascertained, treats (he 

 au(hor of the Oak-plum gall (Fig. 80. «.). in this 

 scurvy manner; and an allied species (Si/ner- 

 ijiisimeratits) operates in the same way u])on (lie 

 (iiill-making larva of (he Oak-bullet gall (Q. 

 (jIoIjkJus, Fitch). .'~i(ill, even in such cxiremc 

 cases as these, the (iuest-lly does not cease to be 

 a vegetable-feeder and a (rue Gues( ; for it is 

 only incidentally, and for the s.ike of monopoli- 

 zing the supply of vegetable food, that he des- 

 troys the gall-maker. Whereas, parasitic larvte 

 feed exclusively upon the bodies of their victims, 

 and make no use whatever of veget.ablc food. 



2nd. Paia.sidc inseiits. These are usually 

 quite dis(inc( from the insects (hey infest, and 

 are much more numerous, liodi in the nnnibcr 

 of distinct species and in (he number of individ- 

 uals belonging to each species, than the Guest- 

 iiisec(s. There are ccr(ain species that peculiarly 

 attack (lie Guest insects, and certain others that 

 confine themselves to the fTall-makers, and it is 

 often difticull (o decide (o which of the two groups 

 (hey should be properly referred. I'arasites be- 

 long to a great variety of diflerciit Families ; but 

 ihose that infest galls made by (i all-dies (Ci/ni^js) 

 and Gall-gnats (Cccidowi/i'i) most of them ap- 

 pertain to the great Chcikis family. For in- 

 s(ance, there are three very disduct C7(«/c(Vflies, 

 the larva' of which prey indillerently upon the 

 gall-iiiiiking larvic of the tw<J kinds of Oak-ap- 

 ples figured above (Figs. 78 and 7il). and may 

 often be found in the central cell ot the gall. 

 The first of these lives inside the body of its vic- 

 tim, as is the more usual practice with parasites, 

 and produces a black and yellow fly (iJec'domu) 

 with a large black patsli on its glassy wings. 

 The second attaches itself externally to the body 

 of i(s victim, and produces a beautiful bright 

 metallic green fly (Callii/iomc) with uniformly 



♦Liir)?er mill ilaiker Ukiii .Vi/ikvi/ii-v oneiti/us Kitcli, 

 tiilKiiiMtiiihle at onee from thiit .speeies liy the aiitei 

 well US (3" liciiifT l,'i-.iointeil insteail nf IJ-jointeil. 



Ill ilis- 



2 as 



