Identify Common Roaches

- It helps to know what to look for -

Summary: Cockroaches develop from eggs that are protected inside very distinctive egg cases while immature cockroach nymphs resemble adults but lack wings. The adults of the important pest species differ in both size and color pattern and are fairly easy to recognize.

Jack DeAngelis, PhD

OSU Ext. Entomologist (ret.)

There are many species of cockroaches but only a few are commonly found in association with dwellings and these are the so called the peridomestic*** species. Since your control options (see How To Control Cockroach Infestations) can vary depending on which cockroach species is present, correct identification can be important.

Cockroach identification can sometimes be made on the basis of egg cases alone. In some pest species like the German cockroach the females carry the egg cases around until just before hatch, but other species like the brownbanded cockroach, drop their egg cases (right) and can be found during inspections.

***peridomestic = associated with human dwellings

two cockroach egg cases, (egg capsules or "ootheca") from brownbanded cockroach; roughly 3/16" long (somewhat smaller than egg cases of the German cockroach); each case contains numerous eggs

Cockroach egg cases

Cockroach eggs are normally tucked safely away inside an egg case, or "ootheca" (above). Each egg case contains many eggs lined up in rows. The egg cases are so distinctive in shape and size that they can often be used to determine the extent and identity of an infestation. Eggs hatch in a few weeks and egg cases break open releasing the young nymphs. Cockroach nymphs look like a small version of the adults except they lack wing development (see image of nymph below).

Common pest cockroaches

German cockroach (Blattella germanica)

The German cockroach [click for picture] is relatively small, about 1/2"-5/8" (16 mm) long, brown in color with two dark stripes behind the head. This cockroach is found worldwide in association with human dwellings and is the one most frequently found infesting homes, apartments, restaurants, and other places where food is handled.

Brownbanded cockroach (Supella longipalpa)

The brownbanded cockroach is relatively small like the German cockroach (less than 5/8" long) but lacks the stripes behind the head and is more oval (wider) in shape when viewed from above.

German cockroach nymph (notice the lack of wings which identifies this insect as a nymph).

American cockroach (Periplaneta americana)

The American cockroach [click for picture] is considerably larger than the German or brownbanded cockroaches at about 1-1/2" (38 mm) long. This cockroach is light reddish brown, or amber in color. Both German and American cockroaches can be found together in the same structure.

Smokybrown cockroach (Periplaneta fuliginosa)

The smokybrown cockroach [click for picture] is closely related to the American roach and also relatively large at about 1-1/2" (38 mm) long. This cockroach is dark brown in color. The smokybrown cockroach is especially common in warm and humid climates such as the southern US.

Cockroach Control

See How to Control Cockroach Infestations for details. A variety of baits, traps and insecticides are available here. New baits are highly effective for control of cockroaches in apartment buildings and other multi-family dwellings.

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