FLIES, MOSQUITOES, AND MIDGES 



237 



long, with four black stripes on the thorax. It is one of the most 

 serious pests of cattle in the South and West, laying its eggs in 

 wounds or sores in which the maggots develop, causing very serious 

 festering sores. Sometimes it oviposits in human nostrils, the 

 work of the larvae not infrequently resulting fatally. 



el 



FlG. 376. The screw-worm fly (Lncilia uiaccllaria] 

 a, l>, c, larva and details of same ; d, pupa ; c, adult ; /, head from side. (After J. B. Smith) 



The tachina-flies (Tachinidae) are found frequenting floxvers ; they 

 somewhat resemble the last group, but are commonly recognized 

 by the numerous stout bristles and hairs with which they are clothed. 

 The adults are mostly of a modest gray color, with thorax streaked 

 with blackish-brown or gray, though some have yellow-banded or 

 red abdomens. The eggs are 

 laid on the bodies of caterpillars 

 or on foliage on which they are 

 feeding, and the maggots are 

 parasitic within them. Any one 

 who has tried rearing moths 

 from their caterpillars will have 

 encountered these flies; for often 

 a score or more will inhabit a 

 large caterpillar. When full 



grown the puparia are formed within the caterpillar or pupa, which 

 never transforms. Some European species which are parasitic on 

 the gypsy moth have been imported into Massachusetts with the 

 hope that they may aid in controlling that pest in this country. 



FIG. 377. A parasitic tachina-fly 

 and its puparium 



(After Weed) 



