REPRODUCTION IN COCKROACH
The cockroach exhibits incomplete metamorphosis. This starts from fertilised eggs to nymph and finally to adult or imago stage i.e.
Egg -> Nymph -> Adult.
Mating begins when the male cockroach introduces sperms into the posterior part of the female’s abdomen through the genital opening. These sperms are then stored in sperm pouch in the body of the female. From here, they meet the eggs as they latter pass towards the exterior. Fertilization is internal.
- Egg stage: The eggs of the cockroach are laid in a horny egg case called ootheca (plural oothecae) formed in the body. This is a chitinous structure which looks like a purse. There are usually 10 – 15 eggs in one egg case and they are arranged in two rows of 5 to 8 eggs per row. The female cockroach carries this egg-case for some time in its abdominal pouch. It then deposits it in a dark, warm and humid place.
- Nymph stage: After some time (about 30 – 100 days) these eggs hatch out into very small, wingless, colourless nymphs. These nymphs feed and grow large and soon begin to moult. During these series of moulting, the wings appear. The nymptial life last for 10 to 16 months.
- Adult stage: the appearance of the wings shows adulthood in the nymph. the adult cockroach now has wings, legs, abdomen, antenna etc fully developed. the cockroach requires about 11 to 20 months to develop from egg to adult.