70 Observations on Cynipidae. 



in some cases it may come to lie in other situations. 

 A slight pushing of the egg higher up or deeper down 

 makes all the difference as to the position of the gall. 

 If the ^%^ lies on the point of a leaf, the gall developes 

 on that spot, and the full grown leaf bears a gall on its 

 point ; but if the ^%% lies deeper in the base of the 

 leaf, the whole leaf-surface is absorbed, and the gall 

 rests directly on the shortened petiole. It may appear 

 sometimes as if the gall had sprung from the shoot 

 itself, but in the angle which it forms with the shoot 

 there is always a little axillary bud, a proof that the 

 gall is merely substituted for the leaf. Lastly, when 

 the ^^% is sunk still deeper into the axis of the bud, 

 the whole bud is absorbed in the gall formation, or in 

 other words a bud-gall is formed. These different 

 varieties are illustrated. (Fig. i6^.) 



The gall matures in the end of May and the flies 

 emerge in the last days of May or in the beginning of 

 June. 



Fly. Size 3 mm. long ; black ; thorax smooth and 

 shining, the sides only faintly punctate, the scutellum 

 rough, on the metathorax a scanty white pubescence ; 

 abdomen brilliantly jet black ; legs orange, trochanters 

 black ; males have similar colouring, but darker legs. 



No experiments have been made with this fly, but 

 as the formation of the gall by the agamous generation, 

 Dryophanta divisa, has been established, there is no 

 doubt that S-pathegaster verrucosus is the sexual genera- 

 tion belonging to it. 



[The red wart gall is found in May on Quercus sesstltflora.'] 



