THE DIPTERA OR TRUE FLIES OF CONNECTICUT 



Introduction 



The Diptera, or true flies, constitute an important order of insects 

 which are rather easily distinguished as a group from the other 

 orders but which nevertheless exhibit a considerable diversity of 

 structure, habits, and habitat. Their numbers may be verj^ great 

 under certain conditions, and their economic importance is significant. 

 An adult fly possesses typically but one pair of well-developed wings, 

 the posterior wings being degenerate, club-shaped organs called hal- 

 teres. The mouth parts are adapted for sucking liquid food and in 

 many species form a piercing apparatus. The larvae are legless mag- 

 gots which may or may not have a well-defined head. The species 

 found in Connecticut vary in size, as adults, from minute midges 

 scarcely a millimeter long to relatively large species of crane-flies, 

 horse-flies, and robber flies, which ma}' measure 25 or 30 millimeters 

 in length. 



There are many different species of flies in the state, and some 

 of these mav be extraordinarily abundant at certain times of the year. 

 The "Check-List of the Insects of Connecticut" (1) published in 1920, 

 contains 1,111 species and varieties, which are definitely recorded up 

 to that date, and the first supplement, published in 1938, contains an 

 additional 454, but this does not include all the forms which doubtless 

 occur here. The "Diptera of New England" (2) lists 3,304 species, 

 and the "List of the Insects of New York" (3) contains 3,615 species. 

 It ma}^ be safely assumed that close to 3,000 species of flies occur in 

 Connecticut. 



The abundance of flies, when suitable breeding places are avail- 

 able, may be very great. The surfaces of stagnant pools on salt 

 marshes sometimes appear blackened with thousands of mosquito 

 larvae. Matheson (4) estimated that over 100,000 adult females of 

 Culex fiinens^ the house mosquito, hibernated in a cellar 4' x 6' x 7' 

 in dimensions. Dr. Deev}^ of Yale University, found 42,000 Corethra 

 larvae per square meter on the bottom of a pond in Branford. In 

 1935 a swarm of Athenx variegata^ a rhagionid fly, emerged from 

 the Housatonic River at Cornwall (5). The females laid their eggs 

 on the under side of two bridges over the river. One spot about 50 

 square feet in area was completely covered with eggs, and the sup- 

 porting timbers of one of the bridges were encrusted with a deposit 

 of eggs and dead flies one-half inch thick. Houseflies breed ext/cn- 

 sively in manure piles. Herms (6) has published an estimate, based 

 on samples of a 1000-pound horse-manure pile exposed only four days 



11 IM -I Q IQCO 



