360 



PROTECTION AGAINST INSECTS. 



B. Diptera. 

 FAMILY I. CECIDOMYIIDAE (GALL-GNATS). 



Flies with long thread-like or nioniliform antennae, with 



10 to 36 joints, usually with 

 whorls of hairs ; body delicate ; 

 wings moderately large with 

 rounded anterior border, con- 

 stricted at the base, often 

 iridescent, with 3 to 5 longi- 

 tudinal veins ; abdomen cylin- 

 drical, consisting of 8 segments, 

 in ? pointed and often furnished 

 with a projecting tubular ovi- 

 positor ; legs slender, the tibiae 

 unarmed at apex. 



Larvae long fusiform legless 

 maggots, slightly flattened, with- 

 out chitinous mouth-armature, 

 but with a chitinous fork or 

 " anchor-piece " embedded in 

 the skin of the ventral surface; 

 usually pale yellowish or reddish. 



The imagos lay their eggs in 

 needles, leaves or bark, in 

 which the young larvae feed by 

 sacking, and thereby cause gall- 

 like swellings. 



Several species are common 

 on willows. 



Fig. 187. Larch twig, with galls 

 made by C. kelneri, Huschl. 

 (Natural size.') 



1. Cccidomyia saliciperda, Duf. (Willotv Gall-gnat). 



a. Description. 



Fly 2 to 3 mm. long ; black-brown ; the wings milky-white 

 with whitish hairs ; antennae shorter than the body. 

 Larva yellowish red. 



b. Life-history, etf. 



The eggs are laid during May in rows on the bark of the 

 branches up to the thickness of one's arm of pollard-willows 



