Article author: Mike Merchant
Most recently reviewed by: Janet Hurley (2018)
Common Name(s): American Cockroach, palmetto bug, waterbug
This is one of the largest common cockroaches in Texas, reaching 1-1/2 to 2 inches. Adults are brown to reddish-brown with a pale brown or yellow border around the outside of the top of the head shield (pronotum). Wings cover the abdomen. They are 1 3/8 to 2 1/8 inches long. Early nymphal stages are grayish-brown. Later stages are reddish-brown.Egg cases (ootheca) are dark reddish-brown to brownish-black and about 3/8 inches. There usually are eight eggs on each side. The droppings of American cockroaches can be confused with mouse droppings, but are shorter with square (rather than pointed) tips.
Another similarly-sized, black-brown, common indoor species is the oriental cockroach, Blatta orientalis Linnaeus, but it differs because the wings on adults are rudimentary on the female and only cover 75% of the abdomen of the male. Other cockroach species come in a variety of sizes and shapes. Most are dark brown with or without color patterns on the body. Occasionally, a whitish cockroach is observed incorrectly thought to be an “albino” form. These are, in fact, roaches that have just molted and have not yet had time to darken their “new” exoskeleton.
There is, however, a pale green cockroach species, the Cuban cockroach, Panchlora nivea (Linnaeus) (Blattodea:Blaberidae), that is occasionally encountered in the Houston area. Other common outdoor species include wood roaches, Parcoblatta spp. (Blatellidae) and the pale-bordered field cockroach, Pseudomops septentrionalis Hebard (Blattaria: Blattellidae).
Origin and Distribution
Indoors, they are found in warm areas with high humidity—boiler rooms, basements,sewers or around drains and pipes. They are more common in large commercial buildings infesting food storage and preparation areas. Outdoors, they are found in moist, shady areas in yards, hollow trees, wood piles and mulch. They are frequent inhabitants of storm drains and sewers.
Habitat & Hosts
This is generally an outdoor species, living in wood piles, decaying trees, palm trees and in sewer systems. Cockroaches have flattened bodies that allow them to enter homes through cracks around loose-fitting doors and windows, and where electric lines or pipes pass through walls. They are mainly active at night and hide in cracks and crevices during the day, preferring dark moist sites in attics and basements. Cockroaches eat almost anything including meats and grease, starchy foods, sweets, baked goods, leather, wallpaper paste, book bindings and sizing. Adults are capable of gliding flights.
American cockroaches undergo simple metamorphosis (egg, nymph, adult). Female cockroaches glue or drop 1/4 inch long bean-like egg capsules (oothecae) containing about 15 eggs on or around infested areas. Nymphs hatch from the egg case that resemble small grayish-brown adult cockroaches without fully developed wings. Nymphs molt 10 to 13 times in over a year (470 to 600 days, depending on temperature) before becoming adults.
ManagementIf you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.
The cockroaches are primarily outdoor cockroaches, so exclusion and sanitation are the primary defenses against these pests. Prompt clean up of spills, proper food storage and waste handling, preventing access to water by fixing plumbing leaks, eliminating harborage and access to the building by sealing cracks and crevices, removing products from cardboard shipping containers before shelving, and inspecting incoming products and rejecting any containing cockroaches, cockroach droppings, or egg cases can all be effective tools in preventing cockroach establishment. Clean up any areas not up to sanitation standards. Remove cardboard and other debris that could serve as shelter. Seal sinks and cracks to remove access to harborage. Ensure no gaps under exit doors.
Chemical Control Measures
Insecticide bait formulations have been developed that are effective on cockroaches. Chemical management options that reduce potential for exposure include insecticide baits in premanufactured, enclosed bait stations or gel or liquid baits placed in cracks and crevices. Bait stations may be used in areas not accessible to children. Use other bait formulations in inaccessible areas where cockroaches may hide.
Use boric acid and silica gel in dry inaccessible voids, cracks, and crevices. Be careful when applying dusts as they may move with air intake or air movement from motors.
Spray-applied residual insecticides can be used around known harborage areas, preferably outdoors or in areas away from human occupancy. Use these pesticides with care around areas where children have access. They should be used only as needed and only in targeted areas.
Always read and follow the label on the pesticide container. The label is the law. Pesticides must be used in accordance with federal, state, and local regulations. Applicators must have proper credentialing to apply pesticides and should always wear all personal protective equipment (PPE) that is specified on the pesticide label. All labels and Material Safety Data Sheets (MSDS) for the pesticide products authorized for use in the IPM program should be maintained on file.