German Cockroach Life Cycle
Life Cycle Stages
German cockroaches are one of the most common cockroach species found in households. These cockroaches undergo three distinct life phases: egg, nymph, and adult. Their entire life cycle spans approximately 100 days, although this is dependent on factors such as temperature, diet, and injuries.
German cockroaches breed continually. In a lifetime, a female is capable of producing almost 400 eggs. Populations grow quickly in optimal conditions. A typical thriving population is comprised of 75 percent nymphs and 25 percent adult roaches.
Eggs & Oothecae
German cockroaches begin life as eggs within an egg casing known as an ootheca. Female German cockroaches carry the oothecae attached to their abdomens until about two days prior to hatching and then deposit them in a protected location. The oothecae are approximately 7 mm long by 2 mm wide, brown in color, and contain approximately 35 eggs. They are very resilient and can survive harsh conditions.
Nymphs emerge from the oothecae as tiny insects. They gradually darken into dark brown or black cockroaches with parallel lines visible upon the pronotum. German cockroach nymphs are wingless and incapable of reproduction. Nymphs molt six to seven times and can develop completely within 100 days under optimal conditions.
The adult stage begins with the last successful molting. At this point, German cockroaches are approximately 15 mm in length and are winged. Adult German cockroaches are nocturnal insects that hide during the day and scavenge at night. Despite their fully developed wings, German cockroaches do not fly.
Encounters & Concerns
The life cycle stages homeowners are most likely to encounter are adult and nymph American cockroaches as they scurry away from perceived dangers, or are in the process of searching for food. Since the female German cockroach carries the egg case until just a few days before eggs begin to hatch, dropped egg cases that may contain unhatched or hatched eggs may be seen in places where German cockroaches congregate.
German cockroach habitats are rife with disease causing organisms, so the chances of adults and nymphs contaminating food, eating utensils, or food preparation surfaces are quite probable. In situations where very large infestations exist, occupants may suffer asthma or other allergic reactions associated with allergens that are associated with both living and dead roaches.