Cockroaches develop through a process called gradual metamorphosis. In this process, the immature roaches look almost like the mature roaches. This process has three stages: egg, nymph, and adult.
When the female produces eggs, she forms a protective case called an ootheca around the eggs. In most cockroach species, the female drops the ootheca in a suitable location before the eggs are ready to hatch. The female roach usually drops the egg case near a food source. When they are ready to hatch, the nymphs break out of their eggs and then break out of the ootheca.
These cockroach larvae, or nymphs, can forage for food immediately. Some, like the German roaches, feed on the droppings of the adult roaches for their first few meals. The nymphs develop without any help from adult roaches. In fact, many adult German roaches eat the newly hatched nymphs.
Many nymphs, like the brownbanded roach nymphs, look very similar to the adults of their species. Some, like the smokeybrown roach, have white markings as nymphs. They lose these markings and turn dark brown as they mature. A few species change color completely as they mature. For example, nymphs of the Cuban roach are dark-colored. By the time they are adults, Cuban roaches are pale green in color.
As they develop, cockroach larvae must shed their exoskeleton, or outer skin, several times. This process is called molting. Before they molt, the nymphs produce a new exoskeleton inside of the old one. The new exoskeleton is soft and flexible. The new exoskeleton is also white or cream-colored.
After molting, the nymph usually spends a few hours hiding while the new exoskeleton dries and hardens. As the exoskeleton dries, the color changes from white to the normal color of the roach species.
As they mature, the nymphs gradually develop wings. By the time they are mature adults, their wings will be fully developed for their species.
The length of the nymph stage varies according to the species of cockroach. American roaches can take almost 2 years to develop from an egg to an adult roach. In contrast, German roaches can develop from an egg to an adult roach in as little as 2 months.
The amount of food that is available is a big factor the development of the cockroach larvae. If food is plentiful, they will grow quickly and develop into adult cockroaches. If food is scarce, it will take longer for the nymphs to grow into adults.
People who are fighting cockroaches can take a giant step if they eliminate as much food for the nymphs as possible. If the roaches are the large outdoor roaches, rake up dead leaves from the yard and the flowerbeds. Clean out the leaves from the rain gutters too.
Keep a lid on the trashcans and pick up anything that falls out of the trash. If there is an outdoor pet, pick up any un-eaten food after the pet has finished eating. This will prevent roaches from eating it during the night. Rinse bottles and cans before they go in the recycle bin and keep the recycle bin away from the house.
To help control the small German roaches, wipe up spills and crumbs promptly. Put away leftover food at night and wash dishes before going to bed – the roaches are active at night and they are scavengers. Empty the trash regularly. Store food in containers with lids that can be sealed.
Cockroach bait is an excellent tool for eliminating roaches. The gel bait and the plastic stations work well for applications in kitchens and bathrooms. Many brands of granular bait are water-resistant, so they can be applied in flowerbeds and ground cover outside.
Make sure to apply enough bait for all of the roaches to eat. Keep the bait filled as long as there is roach activity. Many homeowners prefer to have pest control professionals make the bait applications and the follow-ups that are necessary to eliminate cockroach larvae.