DIPTERA 



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Family Tachinid^e 

 The Tachina-flies 



The tachina-flies are often found about flowers and rank vegetation. 

 They are usually short, stout, and bristly (Fig. 565). 



This is a very large family, more than fourteen hundred species are 

 listed from North America alone; and from 

 the standpoint of the agriculturist it is the 

 most beneficial family of the Diptera. 



This family includes four subfamilies; the 

 Dexiinas, Phasiinae, Megaprosopinae, and the 

 Tachininas, each of which is regarded as a sep- 

 arate family by some writers. 



The larvae are parasitic, chiefly within cater- 

 pillars, but they have been bred from members 

 of several other orders of insects. 



The manner in which the larva finds its 

 way into the body of its host differs greatly 

 in different species of tachinids. In many species the female fastens her 

 eggs to the skin of the caterpillar (Fig. 565); when the larvae hatch they 

 bore their way into their host and live there till they are full-grown. 

 In some of the viviparous species the female punctures the skin of the 

 caterpillar with the sheath of her ovipositor and deposits the larva 

 within the body of the host. Some species deposit their eggs on the 

 leaves of the food-plant of their host; these eggs are swallowed when 

 the leaves are eaten. 



Ftg. 565. — A tachina-fly. Larva, 

 adult, puparium, and eggs upon the 

 fore part of an army-worm. 



Family Muscid^e 

 The Typical Muscids 



With these flies the bristle of the antenna is pubescent or plumose to 

 the tip; but the abdomen is not bristly except near the tip. Here belong 

 many of the best-known members of the Diptera. Among the more 

 important ones are the following : — 



The housefly, Musca domestica. — This is the most familiar repre- 

 sentative of the order Diptera, as it abounds in our dwellings. It lays its 

 eggs in horse-manure and in other decaying organic matter, a single 

 female laying from one hundred and twenty to one hundred and sixty 



Fig. 566. — Wing of the housefly. 



