The oriental cockroach, sometimes commonly called a “waterbug,” is more closely associated with damp areas than the other common cockroaches.
Adult oriental cockroaches are shiny black to dark reddish brown. The males are approximately 1 inch long, whereas the females are slightly larger, about 1.25 inches long. The male’s wings extend 3/4 the length of the abdomen. The female’s wings are very reduced (somewhat resembling wing stubs), pointed, and do not meet in the center. Males and females do not fly. These cockroaches have a somewhat flattened oval shape, spiny legs, and long filamentous antennae. Nymphs (immature stages) resemble the adults, but they are smaller and lack wings. Nymphal early instars (the stage between molts) are shiny reddish brown. Older nymphs are dark reddish brown to black. The egg case (ootheca) is reddish brown when deposited, then changing to black. It is approximately 3/8 inch long. There typically are 16 eggs in each egg case.
Common Name |
Scientific Name |
oriental cockroach |
Blatta orientalis |
Adult oriental cockroach: male (left), female (right).
On average, a female oriental cockroach produces eight oothecae during her lifetime. The female carries her egg case for a few hours or days after it is formed, then she drops or glues it in a sheltered site, often a crack or crevice, near a food source. Eggs hatch in about 60 days (range 42–81 days). There are seven to ten nymphal instars. The oriental cockroach may require several years to complete its development, especially in northern regions. The life span of the adult may be up to six months. Oriental cockroach females are more numerous than males.
The oriental cockroach favors sites with high humidity. Large populations of this species are common in basements, crawl spaces, cellars, sewers, garbage chutes, porch voids, etc. The oriental cockroach prefers temperatures of 68 to 84 degrees F — somewhat lower than the preferred temperatures of other cockroach species. Hence, the oriental cockroach may be the most common species found in cooler basements and cellars. It can withstand extended periods of subfreezing weather.
The oriental cockroach is gregarious, with nymphs and adults often occurring in close proximity to each other. These cockroaches remain near preferred harborage sites during the day, coming out to forage for food and water at night.
The oriental cockroach is a scavenger that feeds on decaying organic matter and a variety of other foods. It is particularly fond of starchy foods.
Cockroaches typically are not tolerated by humans, and the mere presence of these insects is considered a nuisance. Oriental cockroaches also have a strong, unpleasant odor. Because these insects often travel through sewer pipes and live on filth, they are among the most despised of the house-infesting cockroaches.
The oriental cockroach can harbor numerous bacterial and viral pathogens in its feces or on its body. It can contaminate food and food-preparation items and surfaces with disease organisms that result in food poisoning, dysentery, or diarrhea.
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