ORTHOPTERA 



265 



among these are borax, p}'rethnun, sulphur, and phosphorus paste. 



Cockroaches are chiefly inhabitants of warm countries ; although 



nearly one thousand species have been described, few are found in the 



Fig. 301. — Fore wirg of a nymph of a cockroach. 



temperate regions. Only forty-three species have been found in 

 North America north of the Mexican boimdary, and ten of these 

 are probably introduced species (Hebard '17). ^ The cockroaches that 

 are most often found in buildings are two introduced species, the 

 Croton-bug and the Oriental cockroach, and two native species, the 

 American cockroach and the common wood-cockroach. The adults 





Fig. 302. — The Croton-bug: a, first instar; h, second instar; c, third instar; d, 

 fourth instar; e, adult; /, adult female with egg-case; g, egg-case, enlarged; 

 h, adult with the wings spread. All natural size except g. (From Howard 

 and Marlatt.) 



of these four species can be separated by the following table. For 

 tables separating all North American species see Hebard ('17). 



A. With well-developed tegmina. 



B. Tegmina extending to or beyond the tip of the abdomen. 



C. Body about 12 mm. in length The Crototi-bug 



CC. Body 16 mm. or more in length. 



