Cockroaches

Diagram showing the different body regions and parts of a cockroach — The basic cockroach body showing the antennae, head, mouth, pronotum, legs, wings, abdomen and cerci. Photo provided by UNL Entomology.

By: Kait Chapman

Order: Blattodea

View this information as a printable brochure, available in English and Spanish.

View Nebraska Extension's in-depth Cockroach Management Manual (Spanish version coming soon!).

Cockroaches may infest homes and other man-made structures.
Because of their connection to filth, they are potential vectors of food poisoning microorganisms.
Cockroaches may trigger serious allergic reactions in sensitive individuals.
Proper sanitation is a key element in managing cockroach infestations.

Effective management of cockroaches often combines non-chemical and chemical treatment options. Whether you choose the do-it-yourself approach or hire a pest management professional, there are several things you can do to reduce or eradicate cockroach populations.

For questions regarding cockroach identification and management, contact your local Extension office.

Identification

Cockroaches have oval-shaped bodies, threadlike antennae, a head hidden behind a large shield-like pronotum, leathery wings (when present) and a pair of cerci at the end of their abdomen. There are four species of cockroaches that will infest residences in Nebraska:

American cockroach
Oriental cockroach
Brownbanded cockroach
German cockroach

Wood cockroaches will sometimes be found in residences, but cannot reproduce indoors. Different cockroach species have different life cycles, behaviors and habitats. Identifying what species of cockroach you are dealing with can help you make better management decisions. For insect diagnostic services including cockroach identification, contact your local Extension office.

American Cockroaches

American cockroach adults, immature nymphs, and egg case — All life stages of the American cockroach. Photo provided by UNL Entomology.

American cockroaches are the largest cockroach species in the United States. They favor warm, moist places and are typically found in sewers, basements and ground floors. In northern states, they are abundant in many cities’ sewer systems. In homes, they are most common in boiler rooms, heated steam tunnels, basements, under water heaters, around pipes and in wet floor drains.

Identifying characteristics:

Adults reach 1 1/2 inches (38 mm) long
Reddish brown with an "M" marking behind their head
Adults possess long wings that cover the abdomen
Nymphs are wingless and lighter in color than the adults

Oriental Cockroaches

Oriental cockroach adults, immature nymphs, and egg case — All life stages of the Oriental cockroach. Photo provided by UNL Entomology.

Oriental cockroaches are sometimes called “waterbugs” due to their affinity for humid, moist areas. Outdoors, these are areas with high organic matter like wood chips, mulch and soil. Indoors, oriental cockroaches are commonly found in basements, bathrooms, floor drains, crawl spaces, exterior foundations under concrete slabs and areas with moisture issues. Unlike German and brownbanded cockroaches, oriental cockroaches can live primarily outdoors. They will often move indoors during hot, dry periods as they prefer temperatures below 84°F.

Identifying characteristics:

Adults reach 1 1/4 inches (32 mm) long
Dark brown to black in color
Adult males have wings which are shorter than the abdomen
Adult females have short, rudimentary wings
Nymphs are wingless and lighter in color than the adults

Brownbanded Cockroaches

Brownbanded cockroach adults, immature nymphs, and egg case — All life stages of the Brownbanded cockroach. Photo provided by UNL Entomology.

Similar to the German cockroach, brownbanded cockroaches are also considered domestic and depend on indoor human dwellings for food, water and harborage, though they are far less prevalent. Different from the German cockroach, however, is their tendency to aggregate in warmer areas, higher off the floor and away from water sources. Brownbanded cockroaches build up their highest populations in areas of high temperatures and do not require as much water as German cockroaches do. Harborage preferences for the brownbanded cockroach include cabinets, closet shelves, behind pictures, refrigerator motors, electronics and television sets. Because of this behavior, conventional control strategies that focus on ground areas are not as effective against brownbanded cockroaches.

Identifying characteristics:

Adults reach 1/2 inch (14 mm) long
Distinct horizontal yellow bands along their wings
Adult males have gold-brown bodies with wings longer than the abdomen
Adult females have dark brown, tear-drop shaped bodies with wings shorter than the abdomen
Nymphs have two horizontal pale bands on the body

German Cockroaches

German cockroach adults, immature nymphs, and egg case — All life stages of the German cockroach. Photo provided by UNL Entomology.

German and oriental cockroaches are the most common found in North America. Reproductive females may be seen with egg cases protruding from the end of her abdomen. Infestations are often associated with poor sanitation, particularly around food-handling areas. This is because German cockroaches aggregate in warm, humid and dark places with ample food and water, such as kitchens and bathrooms. Immature German cockroaches will feed on the feces of adults and do not need to venture far to find food. This means there are more cockroaches hiding (in harborage areas) than those that are actually seen. German cockroaches are commonly found in and around cracks and crevices of countertops, wall and ceiling voids, refrigerators, dishwashers, stoves, dryers, water heaters and bathroom fixtures.

Identifying characteristics:

Adults reach 1/2 inch (14 mm) long
Adults are light brown with two dark longitudinal bands behind the head
Adults have fully developed wings
Nymphs are wingless with dark longitudinal stripes along their back

Life Cycle

All cockroaches undergo a gradual metamorphosis with three life stages: egg, nymph (immature) and adult. Adult females produce egg cases called ootheca, from which a dozen or more cockroaches will hatch. Ootheca are brown in color and symmetrical. Depending on the species, egg cases may be deposited onto surfaces or retained within the female. Once hatched, nymphs resemble adults but are smaller in size and lack wings. Nymphs will undergo several molts (shedding of the exoskeleton) until they reach maturity. Depending on the cockroach species, development time can take between 90 and 800 days.

Management

Prevention

Cockroaches only need three things to survive: water, food and shelter.

Sanitation and exclusion are the two most important elements in cockroach prevention:

Inspect items coming into the home.
Clean spills and crumbs.
Store food in air-tight containers.
Fix leaky plumbing to reduce moisture.
Seal off potential entry locations with appropriate caulk.
Reduce clutter.
Practice timely trash/recycling management.
Keep exterior lights off at night.
Install screens on windows.

Non-Chemical Management Strategies

Mechanical or physical methods provide a low-risk option for control of cockroaches and should be used in tandem with cultural and chemical methods. Trapping, through the use of strategically placed sticky traps are particularly effective for smaller cockroach infestations. You can also physically remove as many cockroaches as possible using a vacuum. Another non-chemical method for cockroach management is the use of hot and cold temperatures. For example, small items can be placed in sealed containers and placed into a freezer overnight to kill cockroaches.

Chemical Management Strategies

There are many different insecticides available for cockroach control. Use low-risk insecticides like bait stations or gel baits placed on wax paper “tacos” for easy placement. Baits are formulated to be attractive to cockroaches, palatable, slow-acting and limit insecticide exposure to people and pets. Placing smaller volumes of a bait, but with greater frequency increases the odds cockroaches will encounter the bait than with larger, less frequent placements.

If cockroach activity does not decrease with baits, consider adding an insecticidal spray labeled for indoor use for cockroaches to your management program. Other insecticides come in a variety of formulations: dusts, ready-to-use (RTU) sprays, aerosols, etc. Different formulations are useful in different areas of a home or building, and each has its advantages and disadvantages. While foggers are easy to use, they can be dangerous and are therefore not recommended for control.

The primary insecticide classes that are used in cockroach control today are:

Avermectins
Borates
Insect Growth Regulators
Neonicotinoids
Oxadiazines
Phenylpyrazoles
Pyrethroids

Pyrethroids are the most common residual insecticides used in cockroach control due to their fast knock-down activity and low-toxicity to mammals. However, due to emerging resistance to pyrethroids and other insecticide classes, look for formulations that uses more than one active ingredient. This increases the insecticide effectiveness and decreases the likelihood of resistance occurring. Be sure to read and follow all insecticide label directions.

Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the University of Nebraska–Lincoln is implied. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area.

Authors:

Kait Chapman, M.S., Urban Entomology Extension Educator, Nebraska Extension in Lancaster County

Jody Green, Ph.D., Urban Entomology Extension Educator, Nebraska Extension in Douglas-Sarpy Counties