186 



INJURIOUS INSECTS OF 1904. 



insects, have suffered from this pest. Our efforts to breed the fly 

 from the gall have at last been successful, and the adult insect is 

 shown in Fig. 169. The larva which comes from its egg lives 

 within and helps form the gall, and is shown in Fig. 170. This fly, 

 an expert in this group states, is probably Cecidoinvia ucgiuidinis 

 Gill. 



Fig. 170. 



Fig. 169. — Fly bred from Box Elder Leaf Gall. Much enlarged. Original. 

 Fig. 170. — Maggot of Fly shown in Fig. 169. Much enlarged. Original. 

 The small line near the fly, as in other drawings in this report, shows the natural size 

 of the insect. 



Another tiny fly belonging to the same genus, C. aceris, Fig. 172, 

 has this year affected soft maples, causing a rolling of the leaves, 

 in which very imperfect gall lives the larva. 



Two hymenopterous parasites, Tctrastichus sp. and Mcraporus 

 sp., upon this fly were bred from the larvje in our laboratory. An- 

 other parasite is shown in Fig. 173. 



The work of this fly was first observed by us in July, and flies is- 

 sued in our breeding jars the latter part of that month, between 



