CATALOGUE OF INSECTS. 



G67 



HYPODERMA Clark. 



E. lineata Villers. The " Ox Warble " : Hamilton (U S Ag). 

 H. bovis De Geer. Atlantic City, Belvidere (U S Ag). 



These species live under the skin and form tumors and ulcers. 



CESTRUS Linn. 



O. ovis Linn. The sheep-bot ; re- 

 corded from New Jersey. This 

 species lives in the nasal and 

 other head passages of sheep, 

 and causes a disease known as 

 blind staggers, often resulting 

 in death. 



CTJTEREBRA Clark. 



C. buccata Fabr. Ocean Co., June 

 (Sm), Dunnfield, Del. Water 

 Gap, VII, 12. Also a species 

 living under the skin. 



Fig. 313.— The sheep-bot, CEstrus 07is: 1, 2, flies, 

 wings closed and open; 3, pupa; 4, 5, full- 

 grown larvje ; 0, young larva. 



Family TACHINIDiE. 



The Tachina flies are almost all parasitic and of the very highest usefulness, 

 since they form the chief control of many injurious caterpillars. They resemble 

 house-flies, flesh-flies, and blue-bottles in appearance, but are much more 



bristly, sometimes formidable looking from the 

 array of sharp points projecting in every direc- 

 tion. The bristle on the third antennal joint is 

 always bare, and this is the best character for 

 the recognition of the family. 



These flies lay their eggs on the outside of the 

 caterpillar, usually just back of the head, where 

 the larva cannot easily get at them. They are 

 white in color and quite large enough to be 

 easily seen. 



Cut- worms are a common prey of these Hies : 

 — sometimes of hundreds of such larvae gathered 

 not two per cent, will be free of these white 

 eggs. In an army worm year sometimes scarcely 

 one per cent, of the last brood is free. Anywhere from one to 100 grubs may 

 infest a single caterpillar, depending upon the size of the host. 



Fig. 314. — Tachinid parasite on cut 



worms showing larva, pupa and 



adult, as well as the eggs 



on the anterior segments 



of a caterpillar. 



