76 ARTHROPODS 



malarial fevers. What time of the year are they most abun- 

 dant? Why? What effect does cleanhness have on the 

 number of flies and mosquitoes? How do they spend the 

 vi^inter? How do they defend themselves? 



What are the habits of the mosquito, the horse fly and 

 the botfly ? 



Classification. — From A. E. Popenoe. — By this table flies can 

 be traced to their families; for further identification consult 

 a specialist. 



Table of the Principal Families of Diptera. 



Section i. Nemocera. Antennae of more than six 

 joints ; palpi four or five-jointed. 



Culicidae. Mosquitoes. 



Ocelli none; thorax without transverse suture; costal vein con- 

 tinued around the margm of the wing, fringed with scales; larvae 

 and pupae aquatic. 



Tipididae. Crane flies. 



Ocelli none — except in one genus; thorax with a V-shaped 

 transverse suture; legs very elongated; haustellum short, terminated 

 by two large, fleshy lips; palpi longer than proboscis; four-jointed. 



Section 2. Brachycera. Antennae short, not having 

 apparently more than three distinct joints ; palpi one or two- 

 jointed. 



Stratiomyidae. 



Third joint of antennae annulated, sometimes divided into several 

 portions; tibiae without spurs. Costal vein reaching only to middle 

 of wing; three basal cells much prolonged. 



Tabanidae. Breeze flies, horseflies. 



Third joint of antennae annulated, rarely divided into distinct 

 joints, always without style or bristle; haustellum of the male with 



