The biology of Cockroaches

There are four species of Cockroaches common to the Northwest. They are German, American, and Oriental and Brown-Banded Cockroaches. Each variety has three stages of life: egg, nymph and adult. Eggs occur in "sacs" that are attached to the abdomen of the female until just prior to hatching. Nymph Cockroaches emerge without wings. Mature roaches have wings, however, most will rarely fly. As a general rule, Cockroaches prefer to live near a daily supply of water. They can live without food for up to a month, but they can only go without water for a week or so. Here are some pictures and a quick biology of the four most common Northwest Cockroaches:

German Cockroach

Adults are brown in color, around ⁵⁄₈ of an inch long and have a life span of about 200 days. In homes, the German roach will usually live in the kitchen or bathroom. In commercial settings, they will accumulate anywhere there are small cracks, moisture and food. That food can be a grease residue on surfaces or food particles left in cracks and crevices. They are commonly found around sewer pipes, in cabinets, around (or even in) the refrigerator, around the stove and behind moldings.

American Cockroach

American cockroaches range from 1½ to more than 2 inches in length. They are a rusty, red-brown in color and can live up to a year. American roaches prefer warm habitats such as basements or crawlspaces. Due to their preferred dwelling, we do not see as many problems with these cockroaches in Northwest residential areas. However, we do see them in city centers where warm boilers and pipe chases provide a temperate environment. Occasionally, in large buildings you can see these cockroaches moving along the sewer pipes, boiler pipes, electrical wires and other inter-structural avenues, but they prefer to stay out of sight.

Oriental Cockroach

Oriental cockroaches are dark brown in color, almost appearing black. They are about 1 to 1½ inches in length and live anywhere from 18 to 30 months from hatching. These roaches live in the crawlspace areas, outside under leaves, and in various kinds of accumulated, decaying materials. Oriental roaches can tolerate cooler temperatures and are able to live outside through the winter if water is available.

Brown-Banded Cockroach

Brown-Banded Cockroaches are brown, of course! The females have wings that are shorter than their abdomen as well as 2 light brown stripes across the abdomen. Males have wings that are longer than the abdomen and are predominantly light brown. Brown-Banded Cockroaches are about ½ to ¾ of an inch long and live for anywhere from 95 to 276 days. They prefer drier, warmer places which are off the floor. When present, they can usually be found behind pictures, in furniture, computers and other warm places.

Control Measures:

To begin, let us consider the Cockroach as a living thing. Roaches need three things to live: food, water and shelter. They can live up to a month without food, but prefer a more steady food supply. Cockroaches often nest near a consistent source of water and are often found in small cracks and crevices.

The first thing that needs to be addressed is sanitation. Are there unsanitary conditions which are sustaining the Cockroaches such as greasy surfaces or dirty floors. Are cooking areas or food preparation areas clean? Unsanitary situations are favorable to Cockroaches, so the first thing to do is to make sure that your structure is free of filth or water leaks. Roaches like to hide in small cracks and crevices that are less than inch wide, consequently any gaps which can be eliminated should be.

Generally, a baiting program is the most successful plan for getting rid of Cockroaches. Dusts and aerosol pesticides may also be used for controlling Cockroaches.