286 



HABITS OF IMAGINES 



The imagines are found in great numbers in the vicinity of lakes, 

 ponds, rivers, or other bodies of water. They are particularlv numer- 

 ous at lights at night. Many of the species do not appear to feed in 

 this stage, but some are found on flowers, evidently partaking of the 

 nectar or feeding on the pollen, and I have seen one species feed upon 

 moist fly-specks on a store-window at night. 



For a further discussion of the habits of this family see my paper 

 on the Illinois species listed at the end of this summary. 



Keys to Subfamilies 



larvae 



1. Antennae retractile; labium with 4 to 7 teeth, reversible internally; 

 thoracic segments usually more or less dilated Tanypinae. 



— Antennae not retractile ; labium usually with more than 7 teeth, not 



reversible ; abdominal thoracic segments not dilated 



Chironominae. 



pupae 



1. Thorax much distended, the head much below upper level thereof; 

 thoracic respiratory organs simple, egg- or cornucopia-shaped; 

 abdominal segments without strong dorsal spinules ; apical 

 processes flat, sometimes rounded at apices and with a few strap- 

 like hairs on margins Tanypinae. 



— Thorax not much distended, the head not much below the upper 



level thereof; thoracic respiratory organs branched, often with 

 many thread-like filaments, or if simple the abdomen has usually 

 dorsal spinules and the apical segment has the pair of processes 

 pointed Chironominae. 



imagines 



1. Medio-cubital cross- vein present ; wings frequently hairy ; antennae 

 in both sexes with 15 joints ; male hypopygium with each side con- 

 sisting of a short basal piece and an apical slender process which 

 is usually curved and acute at tip Tanypinae. 



— Medio-cubital cross-vein absent, or if present the antenna of the 



female has only 8 joints and the hypopygium of the male has in ad- 

 dition to the 2 pieces present in Tanypinae another piece project- 

 ing along the inner side of the basal portion which bears a fringe 

 of long hairs; antenna of male 15-jointed, occasionally with fewer 

 joints, that of female 8-jointed Chironominae. 



