Strains of the German cockroach resistant to lindane, chlordane, and DDT were compared with a normal strain as to incubation period of eggs, developmental period of nymphs, and longevity of adults.

The resistant strains were more heterogeneous than the normal, with the exceptions of the chlordane-resistant males and females of the nymphal developmental study and all the resistant males in the longevity study. The incubation period of the DDT-resistant strain was shorter than that of the normal and the other two resistant strains. The DDT- and lindane-resistant strains had longer nymphal developmental periods than the other two strains. The resistant females lived significantly longer than the normal females. The sex ratio approached unity in all strains.

Correlation of resistance with differences found in this study gave variable results. The field-originated strain (chlordane-resistant) was similar to the normal strain in average length of incubation and nymphal developmental periods, but similar to the other resistant strains in longevity. On the other hand, rather consistent differences were found between the normal strain and those with laboratory-induced resistance (DDT and lindane strains).