MAY PLIES AND MIDGES OF NEW YORK 81 



some of the species. It is the practice of the writer to remove 

 one wing and all the legs from one side of at least one specimen 

 of each species and to mount them (preferably dry) upon a slide; 

 this method allows of ready measurement and comparison. 



Characteristics of egg, larva, pupa, and adult 

 The adults may be characterized as follows: More or less 

 mosquito like in form, seldom reaching ten millimeters in 

 length. The head is small, somewhat compressed, palpi usually 

 four-jointed; proboscis short; antennae of variable length, from 

 six to fifteen jointed; the first joint disk-like, the last one 

 elongated, the male antennae usually plumose. Eyes reniform 

 or oval; ocelli rudimentary or wanting. Thorax highly arched, 

 frequently projecting over the head, without transverse suture; 

 scutellum small and hemispherical; metathorax well-developed. 

 Abdomen long and slender, eight- jointed, the hypopygium pro- 

 jecting forceps-like; ovipositor but little developed. Legs usually 

 long and slender; coxae moderately long; tarsi frequently very 

 long. Wings either bare or hairy; the veins of the costal margin 

 being stout and in marked contrast with those in the other part 

 of the wing, which appear to be fading out. Venation variable. 

 The larvae usually have blood or tracheal gills, and are soft- 

 skinned and worm-like. The pupae are free, some are active and 

 resemble C u 1 e x , others float upon the surface of the water 

 and still others remain at the bottom of the pond until ready to 

 emerge. 



The flies with which they might be confused are the crane 

 flies and the mosquitoes. The former (T i p u 1 i d s) are usually 

 larger, have proportionately longer legs, have more numerous 

 and more distinct wing-veins, and have a V-shaped suture upon 

 the dorsum of the thorax. The latter ( C u 1 i c i d s) have scales 

 upon the wing, and all, excepting the' subfamily Core- 

 t h r i n a e , have an elongate biting proboscis. The adults of 

 the genus Chironomus have a peculiar habit of holding their 

 fore legs high above the surface upon which they stand, while the 

 mosquitoes usually hold up their hind legs. 



There is one other family of flies, the Stenoxenidae, which 

 must be distinguished from the Chiromomidae. This 



