90 Observations on Cynipidae. 



21. Aphilotrix marginalis. Schltdl.^ 



Gall. These conical or oval galls are formed on 

 leaves, often several on one leaf. The}^ are of a green 

 colour, or striped with red ; the surface without hairs, 

 but with irregular longitudinal furrows ; always sessile 

 and resting on the leaf by a broad base, which indents 

 the leaf surface. They appear in May and mature in 

 June. (Fig. 21.) 



Rearing the Fly is carried out in the same way 

 as in the last species ; it appears, like it, in April. 



Fly. 2-5-3 "^^- long ; very like the last in colouring. 

 Some specimens are even darker, they can only be 

 distinguished with certainty by the galls. Colour dark 

 brown, the scutellum always pale. The colour of the 

 legs varies from orange to dark brown. 



Experimental breeding. I have repeatedly made 

 experiments in breeding this fly. The flies emerging 

 in April soon began to prick the buds, and both in 

 1876 and 1877 I obtained galls from my experiments. 

 The first sign of gall formation is a little green, or 

 occasionally reddish, thickening of the leaf surface, 

 which quickly grows larger. To enable me more 

 conveniently to compare the formation of this gall 

 with the former, I made a combined experiment, in 

 April 1879, and allowed the last two species to prick 

 the buds of a little oak together. Several buds were 

 pricked under my observation by both flies and 



\} Cynips niargmalis, Schltdl. Andncus marginalis, Mayr. 

 Cameron considers it Aphilotrix quadrilineata occurring on leaves 

 and not a distinct species.] 



