Pest Library | German Cockroaches

Blatella germanica (L.)

German Cockroach - Blatella germanica
Color: Tan to brown to black with 2 parallel lines
Legs: 6
Shape: Oval or Boat shaped
Size: 1/2″ to 5/8″
Antennae: Yes
Region: Throughout the U.S.
The German Cockroach, Croton bug or Steam fly (Blattella germanica) is a small species of cockroach measuring about ½ inch to 5/8 inch long; however, they are known to get bigger. It can be tan through brown to almost black and has two dark parallel lines running from the head to the base of the wings. Although they have wings, they do not fly. The German cockroach is one of the most common and prominent household cockroaches in the world. The German cockroach is originally from Asia, it is very closely related to the Asian Cockroach, and to the casual observer they appear nearly identical and may be mistaken for the other.


The German cockroach is omnivorous and a scavenger. They particularly like starch, sugary foods, grease and meats. In certain situations where there is a shortage of foodstuffs, they may eat household items such as soap, glue and toothpaste or they may even turn cannibalistic, often chewing on the wings and legs of each other.

This cockroach can be seen in the day occasionally, especially if there is a large population or if they have been disturbed. They are most active at night. This type of cockroach can give off an unpleasant odor when excited or frightened.


German cockroaches are the most common and prolific household insect found in the United States. The pest is usually found infesting the kitchen or bathroom but has the ability to live in any portion of any heated structure. They are usually found in dark, secluded harborage areas such as cupboards, behind cabinets, in wall voids or around motor housings in appliances (near dishwashers, stoves, and sinks) and in bathrooms of homes. They prefer a moist environment with a relatively high degree of warmth.


Cockroaches have been reported to spread at least 33 kinds of bacteria, six kinds of parasitic worms, and at least seven other kinds of human pathogens. They can pick up germs on the spines of their legs and bodies as they crawl through decaying matter or sewage and then carry these into food or onto food surfaces.

Different forms of gastroenteritis (food poisoning, dysentery, diarrhea, and other illnesses) appear to be the principal diseases transmitted by German cockroaches.

Germs that cockroaches eat from decaying matter or sewage are protected while in their bodies and may remain infective for several weeks longer than if they had been exposed to cleaning agents, rinse water, or just sunlight and air. Recent medical studies have shown that cockroach allergens cause lots of allergic reactions in inner-city children. They were even shown to cause asthma in children. These allergens build up in deposits of droppings, secretions, cast skins, and dead bodies of roaches.


Once a cockroach infestation gets started, its severity is usually determined by the resources available for cockroach survival – food, water and harborage (i.e., hiding places) – factors we often control. The biggest cockroach problems are often in homes where there is a clutter problem because, the more stuff people have, especially in the kitchen, the more hiding places for roaches. But, clean, neat and tidy kitchens can still have roaches. For example, cockroaches can hide underneath the labels of canned goods and eat the paste off the labels.

Sanitation efforts alone (eliminating food, water, and harborage) may not be enough to eliminate a cockroach problem but will reduce the population and make other control efforts work better.

Getting rid of clutter is extremely important.

Eliminating water and food will make roaches move farther to obtain them and come into contact with baits and other control tactics.

Cleaning cupboards and under/around appliances is important. Keep a vacuum cleaner handy. Vacuuming roaches is an easy way to make a dent in the population. Just be sure to take the vacuum cleaner bag outside afterward.

Good sanitation and habitat reduction, along with vacuuming, surveillance, a baiting program, and some sealing of cracks can usually quickly reduce or eliminate a cockroach population.

* Information courtesy of the National Pest Management Association, Inc.

For more information on South Jersey Cockroaches, check out the articles in AB-Con’s Bug Blog: