Dryophanta scittellaris. 6i 



observers the flies appear in October, and according to 

 others not until March. To ascertain the natural time 

 of emergence the galls must be kept in the open air ; if 

 they are kept in a room undoubtedly the flies appear in 

 November, but this is not the case if they are kept 

 in the open air. The fly certainly begins in October or 

 November to gnaw a passage from the central chamber 

 in which it lies, towards the periphery, but it does so 

 without quitting the gall. On the contrary the fly allows 

 a thin lamella of the outer rind to remain, but so thin is 

 this layer that the lumen of the passage can be seen 

 through it. Yet weeks may still pass before the fly 

 breaks through this slight barrier and emerges from the 

 gall ; this depends entirely upon the weather. If, for 

 example, in December there should be a hard frost, the 

 fly remains within the frozen gall, but as soon as a thaw 

 comes it releases itself, probably because in thawing the 

 gall quickly perishes. I have repeatedly noticed that 

 the warmer days and thaws of January entice the flies 

 out ; but when the frost lasts through January the flight 

 of the flies is delayed until February, or even later 

 should the frost continue. In this case many flies do 

 not appear until March. 



Fly. Size 4 mm. long ; black ; vertex of head 

 reddish brown, as also are the sides of the thorax and 

 sometimes the scutellum ; abdomen jet black and very 

 shining ; legs black except the lower half of the femora 

 and the upper parts of the tibiae which are reddish brown ; 

 the wings are long and the whole insect very hairy, the 

 long hairs standing out from the legs and antennae are 

 characteristic ; the antennae have thirteen joints. 



