CHAPTER XIV 



FLIES, MOSQUITOES, AND MIDGES (DIPTERA) 



Characteristics. Insects with one pair of wings borne by the mesothorax ; 

 the hind-wings represented by a pair of knobbed threads, called halteres ; 

 mouth-parts, suctorial ; metamorphosis, complete. 



Ordinarily all sorts of small insects with membranous wings are 

 indiscriminately called flies, and the term "fly" has been used to 

 form part of a compound name for insects of several different 



orders, such as May- 

 fly, sawfly, gallfly, 

 butterfly, etc., but, 

 considered from the 

 entomological stand- 

 point, a fly is a two- 

 winged insect of the 

 order Diptera. With 

 this in mind, it is al- 

 ways easy to distin- 



guih m ^ ^ nQ 



^tV^r r^-rW Vac a 

 . d 



single pair of wings 

 (except the male scale insects), and the name of the order becomes 

 significant, being derived from dis (two) and pteron (wing). The 

 hind-wings are replaced by a pair of odd, club-shaped organs, 

 called balancers, or halteres, which seem to be concerned with main- 

 taining the equilibrium of the insect and are, of ccurse, peculiar 

 to this order. A few of the parasitic families are wingless. The 

 mouth-parts have already been referred to (see page 18) and 

 are fitted for sucking the juices of plants and animals, though in 

 some there are strong, lancelike mouth-parts fitted for piercing, 

 while in others a large, fleshy proboscis, fitted for rasping and 

 lapping, is developed. 



218 



FIG. 346. The house-fly. (Enlarged) 



a, larva, or maggot; Z>, puparium ; c, adult. (After Howard, 

 United States Department of Agriculture) 



