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 flics, 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 Dipt era. With 

 this in mind, it is al- 

 ways easy to distin- 



guigh ^ ^ nQ 



other order has a 



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



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

 United States Department of Agriculture) 



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 



