84 Observations on Cynipidae. 



[The pink wax gall is found in May on dormant buds of Quercus 

 sessiliflora and Q. pubescens. 

 ,<• ^V Inquilines. Synergus thaumacera in June and July of same year; 

 ' Synergus facialis, S. erythrocerus, and S. pallicornis. 



Parasites. Torytnus anwenus, T. flavipes, Syntontaspis fastuosa, 

 CaUimome ruhriceps, and Lintneria exareolata. Birds frequently pick 

 the larvae out of these galls.] 



19. Neuroterus ostreus. Htg.^ 

 Although I have not succeeded in fixing the genera- 

 tion-cycle of this fly, it appears to me desirable to 

 include a notice of this species. Until now it has been 

 classed with Neuroterus, but it differs so materially from 

 the species oiNeuroterus before described that I propose 

 to separate it from them. 



Gall. This dainty little gall is spherical ; 1-2 mm. in 

 diameter ; grows generally from the midrib on the 

 under side of the oak leaves, and is at first enclosed 

 between two brownish scales. Later it grows beyond 

 the scales which then fall off; it is of a pale yellowish 

 colour, very often marked with red spots. The gall 

 appears in August and September, and when mature 

 falls to the ground. (Fig. 19.) 



When the gall becomes detached from the leaf, the 

 larva is still small ; it is therefore necessary to keep the 

 galls for some time on damp sand. I have had some 

 difficulty in rearing any considerable number of these 

 flies, because as a rule the great bulk of the galls are 

 beset with parasites. Meantime, however, I have ascer- 

 tained that the flies appear at various times. In galls 

 maturing early, larvae are full grown at the beginning of 

 September, and the flies emerge towards the end of 



[^ Andricus ostreiis, Mayr.] 



