68 Observations on Cynipidae. 



gall appears at the end of June and ripens in October. 

 (Fig. i6.) 



Fly. The flies are from 4 to 5 mm. long ; brownish 

 red, with antennae, sutures of the thorax, two stripes 

 on the mesothorax, and the back of the abdomen black ; 

 the legs are brown, the trochanters and tarsal segments 

 partly black ; pubescence the same as in Dryophanta 

 scutellaris. The fly usually emerges at the end of 

 October or beginning of November and sets to work at 

 once to prick the buds. This is another confirmation 

 of a rule that holds good without exception, that gall- 

 flies begin to lay their eggs immediately after leaving 

 the galls, and that no fly passes the winter outside the 

 gall to lay its eggs in the buds early next Spring. With 

 this fly I have made many experiments. 



Experiments in breeding. In October, 1877, I placed 

 several flies on a little oak and covered it over. In the 

 beginning of November I noticed that the flies were 

 pricking the buds. Unlike the two former species of 

 Dryophanta they did not choose the little adventitious 

 buds, but selected the large terminal ones. The ovi- 

 positor was applied as before to the point of the bud, 

 and bored perpendicularly into it. On examining 

 a pricked bud I found two eggs laid on the rudimentary 

 leaves. I knew therefore that more than one egg was 

 laid in a bud, and I was enabled to predict that the galls 

 would be formed on the leaves. But this prediction 

 was not yet to be confirmed, for I obtained no galls. 



In the year 1878, I repeated the experiment; after 

 anumber of flies had been enclosed, they began to prick 

 the buds on October 28. The flies remained alive 



