German cockroaches develop in a three-stage process called gradual metamorphosis. The stages are: egg, nymph, and adult.
Female German roaches produce their eggs in a capsule called an ootheca. There are usually at least 30 eggs in one ootheca, but there can be as many as 60 eggs in one ootheca. The female German roach keeps the ootheca attached to her body until the eggs are almost ready to hatch.
The incubation period for the eggs is about a month. During that time, the female spends most of the time hiding. When the eggs are ready, she puts the capsule in a crack or crevice where the nymphs will be near a food source.
The nymphs are very tiny when they hatch. They are barely visible. Without a magnifying glass, many people do not recognize the nymphs as cockroaches. The nymphs have the same color as the adult German roaches, but they do not have wings.
German roach nymphs shed their skin or molt at least six times while they are developing into adults. The new skin is already developed inside of the old one. The new skin is soft and white for a few hours after the nymph molts. People who see a nymph after it has molted often assume it is an “albino cockroach”.
When the nymphs hatch, they eat whatever is available nearby. Their first few meals usually include droppings of adult cockroaches. After they molt once or twice, they can forage for their own food.
Each time they molt, the nymphs look more like adult roaches. After the last molt, the roaches have fully developed wings. Even though German cockroaches do not fly, the wings are an easy way to identify adult roaches.
Adult German cockroaches are about ¾” long. They are tan-colored insects with two dark lines that run the length of the body. Even though they do not fly, they can climb well and they run very fast.
An infestation of German cockroaches will have all stages – eggs, nymphs, and adults. Because of the number of eggs that the females produce, more than ¾ of the infestation will be nymphs.
Insecticides do not affect the German roach eggs. It is probably easiest to eliminate German roaches by removing the food that the nymphs and adult roaches have been eating.
Gel roach bait can be injected into the cracks and crevices where the roaches hide. The plastic bait stations can be placed in drawers, on shelves, under sinks, and in the motor compartments of appliances.
The secret to German cockroach elimination is to use enough bait for all of the nymphs and adult roaches. The bait should be refilled as long as the roaches are eating it.
This process is not done in one treatment – it can take weeks. Because of that, many people prefer to have a pest control professional make the applications and the follow-up treatments.