There are at least 25 species of cockroaches in Alabama, but only five are serious pests. Cockroaches are also known as palmetto bugs, water bugs, and croton bugs. Most cockroaches are found outdoors. Outdoors, cockroaches are an important source of food for many forms of wildlife. They are also important in nutrient recycling. An Integrated Pest Management (IPM) approach is the best way to control cockroaches. IPM methods incorporate all available control methods into a pest management program. Control methods include sanitation, exclusion, and chemical techniques. Successful cockroach control depends on proper identification and good knowledge of the cockroach lifecycle and habits.
Importance Of Cockroach Control
Cockroaches can: • damage property by chewing on or soiling book bindings, fabric, and other materials. • cause respiratory illness in people who are allergic to the allergens cockroaches produce. • secrete smelly oils that are offensive and can ruin food. • impart odors to dishes that look clean.
Types Of Cockroaches
For pest control purposes, there are two categories of cockroaches—indoor and outdoor. The smaller cockroaches, the German and the brownbanded, are considered “indoor” or domestic species. They are seldom longer than 5⁄8 inch. The German cockroach is the most common indoor cockroach and causes the most persistent problem. The “outdoor” or peridomestic species are American, smokybrown, brown, Australian, and woods roaches. Most adults are about 11⁄4 to 2 inches long and are often called palmetto bugs, although some of the woods roaches can be as small as German cockroaches. Outdoor cockroaches can become an indoor problem when they accidentally come in through an open door or are carried in. Cockroach Life Cycle Cockroaches pass through three stages of development: egg, nymph, and adult. Cockroaches deposit eggs in groups of 20 to 50 in a leathery case or capsule called an ootheca. Usually, the ootheca is dropped or glued to a surface by the female as soon as it is formed. However, the German cockroach carries its egg case. It can be seen protruding from the female’s body until the eggs are ready to hatch. When cockroach nymphs hatch from eggs, they resemble the adults in shape, except that they are much smaller and lack wings. Nymphs shed their skin (molt) several times, increasing in size each time before molting into an adult. Depending on the kind of cockroach, the wings vary from being longer than the body to being small pads. Newly molted cockroaches are soft and white, but harden and darken in color rapidly. Therefore, there are no “albino” cockroaches. Normally, cockroaches molt in protected areas, but in serious infestations, they may be seen in the open. Small cockroaches often produce six to eight generations a year with 30 to 48 eggs per case. Larger cockroaches usually produce one to three generations per year with 10 to 28 eggs per case. All cockroaches are most active at night.
Major Cockroach Pests
German Cockroaches Blattella germanica (L.)
Adults are 1⁄2 to 5⁄8 inch long. They are pale brown or tan with two parallel black streaks on the shield or pronotum which covers the head (Figure 1). Unlike most cockroaches, German cockroach females protect their egg cases by carrying them around. The egg case protrudes from her body until the eggs are nearly ready to hatch. Each case can contain 30 to 48 eggs that require about 2 weeks to hatch. A female German cockroach may produce between one and seven cases during her life. Adults may live 3 to 4 months. German cockroach nymphs are about 1⁄8 inch long when they hatch. They are uniformly dark, except for a light brownish area in the middle of the body.
Brownbanded Cockroaches Supella longipalpa (F.)
Adults are about 5⁄8 inch long. All stages have two light, yellow-brown bands that run across their backs. The bands on adult males may be hard to see since their light brown wings completely cover their narrow bodies. Males are known to fly in warm homes or apartments while females cannot fly. Brownbanded cockroaches may be found anywhere in the house, especially above the floor around cabinets, in room corners, and underneath drawers. They are also found behind pictures, in furniture and appliances, including TVs, microwaves, computers, and radios. These cockroaches are common in public buildings.
American Cockroaches Periplaneta americana (L.)
Adults range in size from 11⁄2 to 2 inches long (Figure 3). Generally, they are red-brown in color, with pale yellow “halo-like” markings on the pronotum above the head. The nymphs are about 3⁄16 inch long when they hatch from the egg case and are initially American cockroaches are often found in dark, moist, warm areas, especially around sewers, storage rooms, and garbage sites. Along the coast, they may be found in trees, especially palmettos. When inside, they generally stay on the basement and first floor levels. Adults may fly on warm evenings.
Smokybrown Cockroaches P. fuliginosa (Serville)
Adults are about 1 to 11⁄2 inches long (Figure 3). As the name implies, they are smoky brown in color. The young nymphs are about 3⁄8 inch long, with black bodies and white markings on the middle of their bodies and on the tips of their antennae. Smokybrown cockroaches prefer dark, humid environments. They can be very mobile and will use a variety of habitats such as mulch, log piles, thick vegetation, and roofs. In structures, they can be found from the attic to the crawl space. Adults may fly on warm evenings.
Oriental Cockroaches Blatta orientalis (L.)
Adults are 1 to 11⁄4 inches long and dark brown to jet black in color (Figure 4). The wings of the males are not quite as long as the body, while the females have only small wing pads. The nymphs are about 1⁄4 inch long when they hatch and go from red to brown as they develop. These cockroaches prefer dark, damp, relatively cool locations. These cockroaches are commonly found in bathtubs because they have difficulty climbing smooth surfaces. They also can be found in water meter boxes, sewer lines, leaf litter, crawl spaces, and basements. In a structure, they rarely go above the basement level.
This publication was prepared by Faith M. Oi, Extension Entomologist, Assistant Professor, Entomology, Auburn University; Arthur G. Appel, Associate Professor, Entomology, Auburn University; and Eric P. Benson, former Extension Entomologist