494 
[March 
GtUEST gall-fly, Gynips q. tuber? Mtch. Dr. Fitch notices the 
very great similarity between this fly and his G. q.JicAis which is in all 
probability a Gruest gall-fly. (iV. T. Rep. II, §314.) See above pp. 
464—5 and p. 484. 
15. Black-jack oak? (q. nigra.) G-all q. operator 0. S. 
G-all-fly, G. q. operator 0. S. Captured at large by myself, but 
whether in North or South Illinois I cannot be certain. If captured 
in North Illinois, it must inhabit a different species of oak from any 
on which it has hitherto been found. Baron Osten Sacken reared it 
from the black-jack oak (q. nigra) and Mr. Bassett from q. palustris 
and q. ilicifolia, the last of which is not found in Illinois, and the 
other two do not occur near Rock Island, Illinois. (See p. 445.) As 
already stated, my specimen is identical with specimens received by 
me from Mr. Bassett. 
InQUILINES or GtUEST GALL-FLIES. 
16. Synophrus L^viVENTRis 0. S. (^—G.q.ficus? Fitch = (7. <2- 
pisum ? Fitch.) % % bred in June from the gall of G. q. spongijica differ 
as follows from Baron Osten Sacken’s description of a single 9 (0 bred 
from the same gall, but which I believe to have been in reality a % :— 
The head varies from pale yellowish to dark reddish brown, the pale 
individuals having generally a round black spot enclosing the ocelli, 
but sometimes only a small black transverse line connecting them, and 
the darkest individuals having the space behind the eyes and the en¬ 
tire vertex brown-black as far as the insertion of the antennae, and an 
obscure dusky line descending downwards nearly to the mouth from the 
origin of each antenna. The antennae are I5-jointed, joints 13—15 
equal in length, and they vary from yellowish immaculate through yel¬ 
lowish tipped with reddish brown to rufous tipped with brown. The 
abdomen varies from black immaculate to brown-black above on its 
anterior f and pale transparent yellowish on its posterior ^ above and 
on the entire lower surface. The 2nd joint very generally, but not 
always, completely covers the terminal joints. The legs vary from pale 
yellowish to rufous, the tarsal tips always brown, all the 6 femora some¬ 
times vittate above with brown-black. The veins of the wings are 
generally hyaline, but sometimes, even in but moderately dark speci¬ 
mens, they are brownish. Length % .06—.10 inch. Twenty-three % . 
