802 



AN INTRODUCTION TO ENTOMOLOGY 



The moth-like flies are often very minute and rarely exceed 4 mm. 

 in length. Most of the species, so far as is known, feed on nectar 

 or other fluid matter other than blood ; but the species of the genus 

 Phlebotomus are blood-suckers, feeding upon the blood of various rep- 

 tiles, amphibians and mammals, including man ;and it has been found 

 that some exotic species transmit certain diseases of man, as the Euro- 

 pean pappatici fever, or three day fever, and the Peruvian veruga (Riley 

 and Johannsen '15). A single species of this genus, Phlebotomus 

 vexdtor, has been found in the United States; this is a minute species, 

 measuring 1.5 mm. in length. It was taken on Plummer's Island, 

 Maryland. 



The larvas of members of this family are found in various situ- 

 ations; in decaying vegetable matter, in 

 sewage, in cow dung, in exuding sap on tree- 

 trunks, and in streams. 



About thirty species have been de- 

 scribed from the United States. 



Family CHIRONOMID^ 



The Midges 



Fig. 1015. — Antennae of 

 Psychoda: m, antenna of 

 male and the second seg- 

 ment of the same more 

 enlarged; /, antenna of 

 female and the tip en- 

 larged. 



The members of this family are more or 

 less mosquito-like in foi-m, but are usually 

 more delicate than mosquitoes. The ab- 

 domen is usually long and slender; the 

 wings narrow; the legs long and delicate; and the antennas, especially 

 in the males, strongly plumose (Fig. 1016). In fact many of these 

 insects are commonly mistaken for mosquitoes; but only a few of 

 them can bite, the greater number being harmless. 



The midges are most easily distinguished from mosquitoes by 

 the structure of the wings (Fig. 1017). These are furnished with 

 fewer and usually less distinct veins; and the veins, although some- 

 times hairy, are not fringed with scale-like 

 hairs. There is a marked contrast between 

 the stouter and darker colored veins near th'^ 

 costal border of the v/ing and those on the 

 other parts of the wing, which seem to be 

 fading out. The costal vein is not prolonged 

 into an ambient vein, beyond the apex of the 

 wing. 



In several genera of this family the wings 

 are either absent or vestigial; of these a single 

 species has been found in our fauna. This is 

 Eretmoptera browni, a species described by Pro- 

 fessor Kellogg from tide-pools on the Pacific Coast. In this species 

 the wings are short, strap-like, thickened, and without distinct ve- 

 nation. 



The name midge has been used in an indefinite way, some writers 

 applying it to any minute fly. It is much better, however, to restrict 



Fig. 1016. — Antennfe 

 of Chironomus. f, fe- 

 male; m, male. 



