82 Observations on Cynipidae. 



this fly ovipositing in the open air before I succeeded 

 in being quite certain what gall it produced. From the 

 structure of the ovipositor resembling that of Spathe- 

 gaster Taschenbergi, I suspected that it too pricked 

 leaves. At length I observed in June, 1876, several flies 

 pricking the veins on the under sides of oak leaves : 

 I was deceived by an unfortunate accident, and led to 

 assert that Trigonaspis crustalis produced Dryophanta 

 scutellaris galls, which also occur on leaves ^ In the 

 year 1878, I made a successful experiment in breeding 

 on isolated oaks with Trigonaspis crustalis. It is not 

 difficult to make the flies oviposit provided we have an 

 oak with quite tender leaves at our disposal. The flies 

 do not touch full-grown leaves, they only select those 

 with veins still soft and tender. They usually prick the 

 leaves in the evening, or in deep shade in daytime. 

 The fecundation of the females must first take place. 



If the fly is going to oviposit, it can be recognized at 

 once by the characteristic position it assumes ; first it 

 wanders over the under surface of the leaves, incessantly 

 using its antennae, at last it stops, directs its abdomen 

 almost perpendicularly towards the angle formed by 

 the vein of the leaf with the leaf-surface, and then cuts 

 into the side of the vein. Trigonaspis crustalis makes 

 a whole row of punctures into a single leaf, and the 

 wounds in the veins can be plainly distinguished after- 



^ On June 24, 1876, several leaves were pricked under my eye by 

 Trigonaspts crustalis. In July, Dryophanta scutellaris galls were 

 formed upon them. These same leaves had also been pricked by 

 Spathegaster Taschenbergi, and as I had omitted to examine them again 

 later, I did not know that other galls were forming there. 



