Forest Huval, Reagan, Thomas E., Carlton, Christopher E.
The German cockroach (Blattella germanica) is a common urban pest that is famous for infestations and causing unsanitary living conditions. Adults grow to a length of 0.3 to 0.5 inches (10-13 mm). Adults are easily recognized by their light brown or tan coloration with two black horizontal stripes located on the pronotum immediately behind the head. Nymphs possess black stripes down the entire body. The Asian cockroaches (Blatella asahinai) greatly resemble the German cockroach, but they are not pests. This species differs because the coloration of the pronotum is paler, the black pronotal lines are less distinct, the abdomen is shorter, and it can fly. Asian cockroaches do not infest homes and are typically found outdoors but may wander into homes on occasion.
Adult German cockroach. Forest Huval.
Asian cockroach. Forest Huval.
German nymph. Forest Huval.
Ootheca. Forest Huval.
German cockroach females carry their egg cases until just before they hatch and then deposit it. Each egg case, or ootheca, contains between 30 to 40 eggs. German cockroaches are known for their ability to reproduce quickly and under extreme conditions can even reproduce asexually. Females only need to mate once to be able to produce offspring for nearly a lifetime. German cockroaches can survive from 100 to 200 days.
German cockroaches prefer to live in tight, dark, warm areas where there is constant contact with multiple surfaces. They are commonly found in areas where the temperature is warm and humid and food is abundant. Common infestations include kitchens, bathrooms, pantries and storage areas. Medical studies have shown that German cockroaches can cause allergic reactions and can exacerbate asthma attacks. When large infestations occur, pathogens, germs and bacteria that they pick up or ingest can be transmitted as cockroaches explore and forage.
Improved sanitation is an effective way to help control infestations. Keeping an open clutter-free environment will deprive cockroaches of the dark, tight, humid conditions they prefer. Older houses with insufficient sealing are susceptible to outdoor cockroaches invading the house. Sealing all entrances around doors, pipes and ventilated spaces will greatly diminish outdoor cockroaches moving indoors. Insecticide treatments are available in a wide variety of formulations, including baits, sprays, dusts and powders. Sticky traps can be used as a nontoxic alternative to reduce population size. If there is evidence of cockroach infestation, contact your nearest AgCenter extension agent and a licensed exterminator for service.
Litonjua, A. A., Carey, V. J., Burge, H. A., Weiss, S. T., & Gold, D. R. (2001). Exposure to cockroach allergen in the home is associated with incident doctor-diagnosed asthma and recurrent wheezing. Journal of Allergy and Clinical Immunology, 107(1), 41-47.