74 



NORTH AMERICAN DIPTERA 



Family Ceratopog^onidse — The Biting Midges 





Culicoides species. 



Very small, slender flies, rarely 5 mm. in length. 



Head small, spheroidal and rounded behind or hemispherical and 

 flattened behind; ocelli absent or practically so; antenna? slender, usually 

 with fourteen segments and a fifteenth microscopic one, the apical three 

 to five segments lengthened, the basal swollen; mouth parts complete, 

 adapted for biting. Thorax rather oval, shorter than in the Chirono- 

 midffi; pronotum never prominent; metanotum rather rounded, never 

 with a longitudinal groove; scutellum small, hemispherical, usually 

 bearing distinct bristles. Wings of moderate width, folded flat over 

 the back when at rest; second vein absent, fourtli vein generally fur- 

 cate; alula very narrow; squamae never completely fringed. Legs 

 moderately long, the posterior pair longest; femora and tibite sometimes 

 swollen, the former sometimes with spines beneath; pulvilli present or 

 absent. Abdomen elongate; genitalia exposed; ovipositor small. 



The Ceratopogonida? may be readily distinguished from the Chirono- 

 mida? by the characters enumerated above. They are minute or quite 

 small flies and are often serious pests, es])ecially along the seashore, in 

 the tropics and along our rivers and lakes, but are not limited in dis- 

 tribution to large bodies of water. The adults are either predaceous or 

 externally parasitic although no real differentiation can be made. The 

 larger species are known to prey upon small insects while the small 



