193 



never swollen at bases ; thoracic respiratory organs slender, of mod- 

 erate length, sometimes slightly swollen at apices — except in Cteno- 

 phorinae, in which they are heavily chitinized, flattened, and highly 

 glossy; legs exceeding the wings in length. Abdomen with i or 2 

 transverse series of short protuberances on each segment except basal 

 and apical. Palpi recurved at apices. 

 Imago. — See synopsis of families. 



HABITS OF LARVAE 



Most of the larvae are scavengers, feeding on decaying vegeta- 

 tion, in mud containing vegetable debris, or in rotten wood. Occa- 

 sionally some species of Tipula cause injury to crops such as oats and 

 hay, or to pastures, by feeding upon the roots of the growing plants. 

 Many of the species are aquatic or semiaquatic, living among floating 

 vegetable matter along the margins of ponds or streams. The food 

 consists of algae and various kinds of vegetable matter. 



HABITS OF IMAGINES 



The imagines occur commonly in damp situations, especially 

 where there is a rank growth of vegetation. They feed upon nectar 

 of flowers and upon moisture on vegetation and on the ground. Many 

 of the species are readily attracted to lights. 



Keys to Subfamilies 



LARVAE 



1. Mandibles with 2 teeth ; antennae about twice as long as broad ..... 

 Ctenophorinae. 



— Mandibles with more than 3 teeth; antennae about 4 times as long 



as broad Tipulinae. 



PUPAE 



1. Thoracic respiratory organs broad, glossy, and heavily chitinized 

 (PI. XXXII, Fig. 20) Ctenophorinae. 



— Thoracic respiratory organs slender, opaque, not more heavily 



chitinized than dorsum of thorax Tipulinae. 



IMAGINES 



1. Legs very long and slender, the tarsi especially so ; anterior branch 

 of second vein absent, indistinguishable, or perpendicular 



DOLICHOPEZINAE. 



