1864] 
463 
APPENDIX. 
The very curious subject of the Gruest gall-flies or Inquilines has al¬ 
ready been referred to. For our knowledge on this subject, and for an 
explanation of the distinction between the True Giall-flies {Psenidei) 
that make the galls and the Gruest gall-flies (^Inquilinse) that inhabit the 
galls made by the others, without however necessarily starving or de¬ 
stroying them, we backwoods entomologists are indebted to Baron Osten 
Sacken. {Proc. Ent. Soc. Phila. I, pp. 48-9.) That writer has clearly 
shown that Dr. Fitch was not aware of the existence of Gruest gall-flies, 
because, having bred a Guest gall-fly {oneratu?, Harris) from a gall 
made by a true Gall-fly (^. glohuhis Fitch) he supposed that the two 
insects must have come from two different kinds of gall. (Ibid. pp. 
67-8.) Having myself bred this Guest gall-fly from the gall of q. glo¬ 
bulus^ I can confirm the fact of its not being produced from a distinct 
kind of gall. 
I have also reared a very great number of gall-flies from the Oak-fig 
gall (q. ficus Fitch) which correspond accurately with Dr. Fitch’s de¬ 
scription of his Cynips q. ficus^ and which are not true gall-flies but 
inquilines, and identical with the species that I know, as before stated, 
to be an inquiline in the oak-apple of spongfi.ca—Synoplirus Iseviveii- 
tris 0. S. It is therefore not improbable that Dr. Fitch’s Cynips q. 
ficus is an inquiline and a mere synonym of the above-named species, 
with which, as will be shown below, it agrees in the number of its an¬ 
tennal joints, 15 S , 13 9 • Mr. Bassett also bred nothing but “ para¬ 
sites” from this gall, by which term he, as well as Baron Osten Sacken, 
denotes not only the true parasites (^Ichneumomdse, Ghalcididse, &c.) but 
also the Guest gall-flies. Further than this, I have bred another in¬ 
quiline {Synophrus albipes n. sp.) from a gall (^q. fiocci^ apparently 
identical with q. lana Fitch; and as Dr Fitch’s description of his 
Cynips q. lana ( 9 with 15-jointed antennas and 9 only known to him) 
agrees very well with that of % Synophrus Isevivenfris 0. S., which has 
15-jointed antennae and which may readily be mistaken for 9 on account 
of the large size of the % abdomen in this genus, 1 incline to believe that 
in this ca^e also he has described by mistake the Guest gall-fly for the 
True Gall-fly, and that the latter in both of these two cases still re¬ 
mains to be described. In the case of the gall q. fiocci (=q. lana ) 
