300 



NEW YORK STATE MUSEUM 



Introduction. This insect was doubtless introduced with imported 

 nursery stock. Some infested willows were probably used to bind imported 

 trees into bundles, and this is borne out by the fact that the locality where 

 the flies were found is in close proximity to a place where an importer 

 had been in the habit of unpacking stock. 



Life history. Adults were bred from infested galls collected early in 

 the season, from May 22 and onward. Other specimens received directly 

 from the field, June 3 were disclosing flies, showing that in nature the adult 

 issues at this time. The pupa, like those of 

 many Cecidomyiids, wriggles partl\- out of the 

 gall before disclosing the adult, and so many 

 may emerge from a gall that it presents a some- 

 what peculiar appearance after the flies have 

 escaped because of the numerous white, project- 

 ing pupal cases. 



The reddish orange eggs were deposited by 



captive flies on the leaves in irreijular clusters 



Fig. s8 Two antennai segments of European or groups of three to si.x oruiorc. The dura- 



willow gall midge; rt=male; ^=female; . r i 1 r 1 1 1 * 



both much enlarged tiou of the egg Stage and of the larval existence 



was not determined. It seems probable that there is but one annual 

 generation. 



Description. The small black or dark brown flies are about ^s inch in 

 length. The eyes are black, finely granulated, emarginate anteriorly, 

 confluent in the male and nearly so in the female. The male antennae are 

 17 jointed and are about the length of the insect and the female antennae 

 are about half her length. The interesting structures occurring on the 

 segments of the male and female antennae are shown in figure 58. The 

 thorax is ornamented with two converging rows of silvery hairs, and a short 

 row of smaller ones occurs on each humeral angle. The metathorax is 

 tipped with a transverse row of the same vestiture. The venation of the 

 wings, which are sparsely covered and well fringed with dark hairs, is repre- 

 sented in figure 59. The balancers or halteres are slender and tipped with 



