774 REPORT OF NEW JERSEY STATE MUSEUM. 



CESTRUS Linn. 



O. ovis Linn. The sheep-bot. 

 This species lives in the 

 nasal and other head pass- 

 ages of sheep and causes a 

 disease known as staggers, 

 often resulting in death. 



CUTEREBRA Clark. 



C. buccata Fab. Ocean Co. VI 

 (Sm); Dunnfield VII, 12. A 

 species living under the 

 skin of rabbits. 



C. horripilum Clark. Riverton 

 VII, 6. 



Fig. 321. — The sheep-bot, CEstrus oi'is: i 

 flies, wings closed and open; s, pupa; 

 4, 5, full grown larvae; 6, 

 young larva. 



Family TACHINID/E. 



The Tachina flies are almost all parasitic and of the very highest use- 

 fulness, since they form the chief control of many caterpillars. Ttey 

 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 direction. 

 The bristle on the third antennal joint is 

 always bare, and this is the best char- 

 acter for the recognition of the family. 



These flies often lay their eggs on the 

 outside of the caterpillar, usually just back 

 of the head, where the larvae 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 

 flies; sometimes of hundreds of such larva 

 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. 



GYMNOCLYTIA B. & B. (CISTOGASTER.) 

 G. immaculata Macq. Westville VI, 26 (Jn) ; Glassboro VII, 8 (CG) ; 



Clementon V, 30, IX, 5 (Hk). 

 G. occidua Walk. Dover VI, 17, Chester VII, 25, Westville, Atco VII, 12 

 (Jn); Middlesex Co. VII, 7, Jamesburg VII, 4 (Sm). 



Fig. 422. — Tachinid parasite on 

 cut-worms showing larva, 

 pi;pa and adult, as well as 

 the eggs on the anterior 

 segments of a caterpillar. 



GYMNOSOMA Meig. 

 G. fuliginosa Desv. Caldwell (Cr) ; Woodbuiy VI, 7, Clementon VIII, 8, 

 Buena Vista VI, 11, Anglesea VII, 19 (Jn). 



