Cockroaches are a group of insects that most commonly lay eggs. However, there are members of the group that are ovoviviparous or completely viviparous. In these species, the young develop inside the mother’s body as mammals do. The difference is that ovoviviparous species develop inside an egg inside their mother’s body and viviparous species develop inside layers of fluid and tissue as mammals do.
Newly hatched cockroaches are called nymphs. Like many insects, cockroaches go through different growth stages called instars that are characterized by a molt at the end of each instar. This occurs because the hard exoskeleton of the insect is unable to expand with the softer internal tissues.
The development from nymph to adult takes a matter of weeks to a matter of years depending on the species. Adult females attract mates by releasing pheromones in most species. However, there are some species of cockroaches that are parthenogenic or capable of reproduction without males. These species may be strictly parthenogenic or may only use this method of reproduction when males are scarce.
Female cockroaches possess the ability to store sperm from a single mating and use it to fertilize later batches of eggs. For this reason, a single mating can be all that is needed for a female to produce thousands of young depending on the species. Egg development is temperature-dependent and proceeds faster at higher temperatures.
In most species, the female carries the eggs until shortly before they are ready to hatch and then finds a place to hide them. Carrying the eggs on her body allows her to keep them moist, which is required for gestation. She may carry them for a few days to more than two months. A few species practice maternal care and tend to the nymphs for a short period of time after hatching.
“The Cockroach.” Welcome to marlin | marlin. UMass, n.d. Web. 17 Oct. 2012. http://www.bio.umass.edu/biology/kunkel/cockroach_faq.html
” Cockroach Reproduction Physiology.” Department of Entomology | Virginia Tech . N.p., n.d. Web. 17 Oct. 2012. http://science.howstuffworks.com/environmental/life/zoology/insects-arachnids/cockroach2.htm