HOW TO KNOW THE IMMATURE INSECTS 



6a. Thorax conspicuously swollen, almost globose, its anterior profile 

 declivous; stemopleura concealed. 

 Fig. 561 Family MYCETOPHILIDAE 



Pupation takes place mostly in delicate cocoons and 

 a few ore suspended by some loose silk from the sur- 

 face of fungi or other objects. 



Fig. 561. Leia 



oblectobiNt 



Loew. 



6b. Thorax not conspicuously swollen, the anterior profile not sloping 

 downward 7 



7a. Scape of antennae much swollen, globose; abdominal spiracles 

 small or absent; stemopleura enlarged, not concealed by fore 

 coxae and femora. Fig. 562 Family CHIRONOMIDAE 



Some pupae are active and 

 float at water surface, but some 

 remain in the larval tube. The 

 respiratory organs either consist 

 of a pair of branched filaments or 

 -. ^^^ , ,. „ of a simple tube. 



Fig. 562. Tanypus illinoensis Mall. ^ 



7b. Scape of antennae not much swollen; abdominal spiracles distinct; 

 stemopleura not visible, concealed by large coxae and femora of 

 the fore legs Family CECIDOMYIDAE 



8a. Thoracic respiratory organs slender, long and tube-like; legs 

 straight, extending well beyond apices of wings; body without 

 armature except a pair of hairs on anterior margin of head; stemo- 

 pleura concealed Family CECIDOMYIDAE 



8b. Species not in such combination of characters; abdomen usually 

 with hairs or spines, or stemopleura exposed 9 



202 



