DIPTERA. 



TENTH ORDER. DIPTERA, (Gr. dig, dis, twice or two ; 

 pteron, wing.) 



These insects are distinguished by the possession of only two 

 wings and a pair of small knobbed appendages, (as in the com- 

 mon fly and the musquito,) called halterers or poisers. The 

 wings are membranous, and without any covering, except a few 

 hair-like scales, which, in some species, appear at the base. 

 They are never folded upon themselves, remaining expanded 

 when at rest, as in the insects of the preceding order. Their 

 nervation is quite different from that exhibited in the other orders. 

 The mouth is suctorial, and in many, has a fleshy proboscis, that 

 encloses lancets capable of penetrating flesh, or the softer parts 

 of vegetables. In a flfw genera, as the Oestrus or Gad-fly, the 

 mouth is closed. These insects are all small ; but what is 

 wanting in size is made up in numbers. They are every 

 where, and also are attendants upon man, sometimes to his 

 great annoyance ; but it should be remembered, they are highly 

 useful in cleansing the earth's surface of impurities, both animal 

 and vegetable. In this order the transformations are imperfect. 

 The pupae sometimes take the incomplete form, having the 

 limbs visible, and without a cocoon. The larvae are white and 

 fleshy, cylindrical in shape, and without feet. They are seen 

 in carrion and in galls; or in living caterpillars; and sometimes 

 among vegetables pickled with vinegar, and in the brine of salt 

 works. We can only refer to some of the more conspicuous 

 families. 



1. Culicida, represented by the genus Culex, (Lat. a gnat.) This 

 family includes the numerous Gnats and Musquitoes, C. pipiens, 

 (Lat. peeping.) distinguished by the tufted antennae of the males. 

 The pupae of these are active ; the larvae are inhabitants of water ; 

 hence, these insects are abundant, chiefly in damp situations. 

 Mankind are attacked by the female gnats alone ; the lancets of 

 the mouth being in the males fewer and weaker. These insects 

 lay two or three hundred eggs in stagnant water, joined together 

 so as to form a little raft floating upon the water, where they 

 hatch in about three days, producing small greenish worms, that 

 in fifteen days become the wrigglers of open rain-water casks and 

 stagnant pools, breathing through the tail, and darting first one 

 way, and then another. From this pupa state, they emerge as 

 full-grown Musquitoes, Gnats, Midges, &c., breathing through 

 openings in the sides, and ready to pierce the flesh, suck the 

 blood, and instil their inflammatory poison into the wounds made 

 by their pointed proboscis ; four or five generations may be 



