The major factor limiting German cockroach survival appears to be cold temperatures. Studies have shown that German cockroaches were unable to colonize inactive ships during cool temperatures and could not survive in homes without central heating in northern climates. The availability of water, food, and harborage also govern the ability of German cockroaches to establish populations, and limit growth. The entire life cycle is completed in about 100 days. However, factors such as temperature, nutritional status, and strain differences may influence the time required to complete a life cycle.
German cockroaches breed continuously with many overlapping generations present at any one time.
Under ideal conditions, population growth has been shown to be exponential. Actively growing field populations are comprised of 80 percent nymphs and 20 percent adults. The German cockroach is omnivorous, eating table scraps, pet food, and even book bindings. Eggs are carried in an egg case, or ootheca, by the female until just before hatch occurs. Eggs will often hatch from the ootheca while the female is still carrying it.