The name “Dusky Cockroach” is used to describe more than one species of insect. The insects that people refer to as “dusky cockroaches” are also called by other names as well.
In the United Kingdom, the name Dusky Cockroach is used to describe Ectobius iapponicus (L.). This is a small cockroach that is native to the U.K. Females are about 1/3″ long and males are slightly larger. They are dark grayish-brown. The males have a dark brown shield over their head. The females have dark brown abdomens.
These are outdoor roaches that live in grassland and woodland. They occasionally invade homes and businesses. Some scientists refer to this roach as the Tawny cockroach, although there is another species that also goes by that name. That roach is E. pallidus.
Among other people, the name Dusky Cockroach is sometimes used for Periplaneta fuliginosa (Serville). It is also sometimes called Duskybrown cockroach. In the United States, it is commonly called the smokeybrown cockroach.
This is a large cockroach. Adults can reach almost 10.5″ in length. It is shiny, dark brown in color. It is attracted to light and it flies well. Because of this, it often enters homes through gaps in the eaves and through attic vents.
This cockroach has been transported from the United States by cargo containers and airplanes. The smokeybrown roach is now found in Japan, Korea, and Southeast Asia. Outdoors it feeds on plants and decaying leaves. When it has moved indoors, it will feed on anything that is available.
Cockroaches that normally live outdoors and invade occasionally are often called peridomestic. They are easiest to control when they are still outdoors.