1864.] 633 



DROSOPHILID^ffi. 



J. Drosophila amcexa Lw. I bred eight specimens of this ele- 

 gant little insect Aug. 17 — 27, from the gall *S'. strohiloidex. Baron 

 0.steu Sacken, to whom I am under obligations for determining both 

 this and the preceding species, observes as follows in regard to its 

 habits: — '' The genus Drosophila occurs in the vicinity of acid or fer- 

 menting matters, as vinegar, decaying apples, &c., in which the larvae 

 live. D. amoma occurs commonly among decaying leaves, and the oc- 

 currence of its larva in the gall Sfrobi/oiWrs is probably not the gene- 

 ral rule. I have found the fly abundantly in places where hardly anv 

 Willows were to be met with." — As I have 6 specimens, all captiu'ed 

 at large at the same time near Ilock Island, it must be tolerably com- 

 mon there also. 



TACHINID.ffi:. 



A gray species .09 inch long was bred Sept. 1 from the Tenthredi- 

 nidous gall *S'. pomum. It might have been parasitic either upon the 

 author of the gall, or upon a beautiful harlequin-like, 12-banded. Lepi- 

 dopterous larva, which is commonly inquilinous there, but which I 

 have not yet succeeded in raising to the imago. 



A robu.st, blackish species, .1-i inch long, was bred Aug. 18 from the 

 Cecidomyidous gall *S'. brassicoides. It seems almost too large to have 

 infested any of ihe 5 species of Lepidoptera that I have found to be 

 inquilinous in that gall ; but as I bred therefrom a single specimen of 

 the common Loxotsenia rosaceana Harr., which must have accidentally 

 got in among the expanded leaves of the galls, it might possibly have 

 been parasitical upon some such larva. I have neither the facilities, 

 nor the time, nor the requisite experience, to determine the above 2 

 species either generically or specifically, and therefore dismiss them with 

 this brief notice. 



And now, after toiling through all these long and frequently tedious 

 details — after we have seen that the (xall-gnats of the Willow, though 

 they are essentially distinct species, yet resemble one another so closely, 

 that in almost all cases it is difficult, and in some cases impossible to 

 distinguish the imagos one from the other — after we have seen that 

 species inhabiting monothalamous bud-galls of the same fundamental 

 structure, such as the first six described above, are in the imago state 



