Aphilotrix seminationis. 89 



certalnt3^, a result obtained by experiments in breeding 

 carried on for three consecutive years. The flies 

 emerging in the first half of April soon begin to prick 

 the buds, and this they do in exactly the same way as 

 the genus Neuroteriis : the ovipositor is pushed under 

 the bud-scales, glides down to the base, and is then 

 bored into the interior of the bud ; by this means the 

 egg comes unfailingly to lie on the rudimentary leaf. 

 In 1876 I made my first experiment; from April 3 

 to 5 several buds were pricked, and on May 28 two 

 Aphilotrix seminationis galls were formed. In 1877 

 seven buds were pricked, between April 13 and 15, 

 from which I obtained in June four Aphilotrix semina- 

 tionis galls. And lastly, in 1878, I made experiments 

 with flies which had been reared from catkin galls, to 

 convince myself of their indentity with those derived 

 from leaf-galls ; these flies soon began to prick the 

 buds of an oak sapling, and the result was that in the 

 beginning of June, five Aphilotrix seminationis galls 

 were formed on the leaves. There is this peculiarity 

 in the growth of these galls, that after the gall has 

 appeared like a little hairy knob on the unfolding leaf, 

 there is a long pause in its development, and it is quite 

 fourteen days before growth begins again. Those 

 growing on the flower stems have a still longer period 

 of rest, and in these the first sign of gall formation may 

 be simply an enormous thickening of the flower stem. 



[The barley-corn gall is found in May on Qitcrcus sessiliJJora and 

 Q. pubescens. 



Inquilines. Synergus albipes and 5^. facialis, in July of the same 

 year. 



Parasite. Etttytoma rosae.] 



