The male reproductive system of cockroach consists of a pair of testes lying on each lateral side in the 4^th -6^th abdominal segments. The female reproductive system of cockroach consists of two large ovaries, lying laterally in the 2^nd - 6^th abdominal segments. Thus ovaries are longer than testes. Males bear a pair of short, threadlike anal styles which are absent in females. In both sexes, the 10^th segment bears a pair of jointed filamentous structures called anal cerci. A pair of spermatheca is present in the 6th segment of female cockroach which opens into the genital chamber. Their fertilized eggs are encased in capsules called oothecae. Periplaneta americana has a $\mathrm{X}\mathrm{X}-\mathrm{X}\mathrm{O}$ type of sex determination. Females have 34 chromosomes $(32+\mathrm{X}\mathrm{X})$ and males have 33 chromosomes $(32+\mathrm{X}).$