THE HOUSE FLY. 45 



Additional Facts About Plies. 



The house fly belongs to the order Diptera. The 

 name means two wings. The balancers represent 

 another pair of wings in a rudimentary condition, so 

 that flies really have the same number of wings that 

 other insects do. 



All diptera have sucking mouth parts and a com- 

 plete metamorphosis, although in some members 

 of the order, as the mosquito, the pupa is active. 

 The larva of a fly is called a maggot. It is usually 

 found in decaying animal matter. The mosquito 

 lays its eggs in a bunch, which floats on the sur- 

 face of the water. The egg hatches into a wiggler, 

 which swims in the water, coming to the surface to 

 breathe. It breathes through air tubes opening 

 in the tail. The pupa is quite different from the 

 larva, being a club-headed wiggler, living also in 

 the water. 



Some flies lay their eggs in the tissues of plants. 

 The tissues then swell up around the egg, making a 

 gall in which the larva and pupa live and undergo 

 their transformations. These flies are called gall 

 gnats. 



Among the Diptera we find some of the most 

 annoying insects. House flies, cow flies, bot flies, 

 mosquitoes, and gnats, may be mentioned. The 

 Hessian fly is exceedingly injurious to wheat, its 

 injuries entailing a loss of many thousands of 

 dollars every year to the farmers of the United 

 States. 



It is among the Diptera that we find the 

 greatest number of examples of protective mim- 

 icry. There are flies that closely resemble bees, 

 bumblebees, wasps, hornets. In many cases the re- 

 semblance is so close that experienced collectors are 

 deceived. 



