86 Observations on Cynipidae. 



[The oyster gall is found in August on Quercus sessillflora, Q. pedun- 

 culata, and Q. pubescens. 



Inquilines. Synergus tristts in April, and S. Tscheki in June of 

 second year. 



Parasites. Pteromalns bisignatus, Eurytotna rosae, Aulax syn- 

 creptdus.'] 



19^. Spathegaster Aprilinus. Gir. 



Gall. The galls spring from buds and are of different 

 sizes. They are round, of a pale or greenish yellow 

 colour, and are surrounded at the base by bud-scales. 

 They are very thin-walled and each contains one or 

 more larva chambers which may sometimes be recognized 

 through the outer wall. The gall appears in the end of 

 April or beginning of May, and matures very quickly. 

 (Fig. I9^) 



The fly emerges in the end of May. 



Ply. Length 2-5 mm.; black; thorax somewhat 

 shining, scutellum wrinkled ; abdomen shining ; an- 

 tennae black ; legs dark yellow, coxae and basal half 

 of the femora blackish ; males and females similar in 

 colouring. I have not succeeded in breeding this fly. 



This species is distinguished from the closely allied 

 Spathegaster Taschenbergt a.nd S. similis by the ovipositor 

 being longer in proportion, pointed, and straight. 



[The April bud-gall is found on Quercus pubescens a.nd Q. sessiltflora. 

 Inquilines. Ccroptres arator in June of the first year. Platymesopus 

 tibialis in May of the first year.] 



In the case of those gall-flies which have hitherto 

 been described we have observed this curious circum- 

 stance, that they each possess a regular generation- 

 cycle, consisting of two forms more or less distinct. 



