German cockroaches are the most common cockroach species found in houses, apartments, condominiums, hotels, restaurants, and just about any other kind of business in the United States that has a cockroach infestation.
German roaches are associated with a variety of human illnesses as previously mentioned. German cockroaches are so successful and therefore difficult to control for a variety of reasons.
German roaches have a larger number of eggs per egg capsule than other roaches. The female carries the eggs inside the capsule as they develop into nymphs. Thus the nymphs that are born alive have a much better chance of survival. German roaches exhibit the shortest time from egg to sexual maturity. These factors combine to give the German cockroach a huge reproductive potential. German cockroach nymphs are very small, allowing them to conceal themselves in the tiniest of cracks and crevices where they are protected.
A typical home or industrial kitchen has literally thousands of protected cracks and crevices where nymph roaches can hide. A typical female lives about one year. She can produce 4-8 egg capsules (ootheca) in that time frame. Each capsule carries 30-50 eggs. From egg to sexual maturity averages about 3-4 months. If you start looking at those numbers, it is not hard to imagine how a German cockroach infestation can explode in a matter of a few months.
German cockroaches are also extremely adaptable as far as what they can eat and the environmental conditions in which they can survive. All of these facts combine to give the German cockroach an almost unparalleled advantage in establishing successful populations and in resisting control measures.
Control of German cockroach infestations requires co-operation from the business/home owner and the pest control professional. Once co-operation is established, and both parties agree to their responsibilities and a well thought out treatment plan is developed, cockroaches can be controlled and eliminated. If co-operation does not exist, treatments will not be successful. One time treatments for German cockroaches are typically not effective.