Turkestan cockroach
The Turkestan cockroach is an invasive species that is now very common in California’s residential outdoor areas. With access to good habitat and food sources, they can quickly develop very high populations. Common habitats around homes are wood and debris piles, irrigation and water meter boxes, crevices in pavement or rock walls, and outdoor drainage pipes. They are also common in public storm drains and sanitary sewers. These habitats provide the dark, moist hiding places that cockroaches prefer. They come out at night to feed. While some may occasionally wander into homes, especially where outdoor populations are high, they will not establish indoor populations.
Identification
The female Turkestan cockroach is about 1 inch long. They are dark brown to black with cream-colored markings along the margins of their wing buds. Females are often confused with the oriental cockroach but can usually be distinguished by these markings. Oriental cockroaches also have wider thoraxes than do Turkestan cockroaches.
The image below compares an adult female Turkestan cockroach (A), and adult female oriental cockroach (B). (Credit: Dong-Hwan Choe, UC Riverside)
The male Turkestan cockroach is slightly smaller than the female and has yellowish-tan wings and cream-colored stripes along the edges. Males may be mistaken for American cockroaches, which are about 2 inches long and reddish brown.
In the picture below, male (left) and female (right) Turkestan cockroach are mating on a concrete wall outdoors. (Credit: Andrew M Sutherland, UCCE and UC IPM)
Impact
Turkestan cockroaches live outdoors but can invade indoor spaces in search of water. They live and breed outside and cannot survive indoors. You may find them upside-down and dead in indoor spaces such as garages or near entryways, but as much as you find them disgusting and startling when encountered, rest assured Turkestan cockroaches will not establish and thrive in indoor environments. Like all outdoor pest cockroaches, the Turkestan cockroach is seen as both a serious nuisance pest and potentially a public health pest since it can carry disease-causing organisms.
The image below shows egg cases (oothecas) of the Turkestan cockroach deposited in moist soil under an outdoor barrel of kitchen grease.
Solutions
Good sanitation, especially around outdoor trash storage areas, and exclusion from the home are important for effective control; pesticides alone will not solve cockroach problems. When using insecticides, baits provide better control than sprays.
Reduce sprinkler irrigation, if possible. Fix plumbing and irrigation leaks to reduce water availability. Reduce moisture around the perimeter of buildings by ensuring proper soil grading and avoiding planting within one foot of the foundation. Consider using gravel or bare soil instead of mulch or groundcovers in these areas.
Don’t leave pet food outdoors, especially at night. Keep trash in containers with tight lids and regularly clean outdoor trash storage areas to remove food residues. Remove trash and stored items such as stacks of lumber or firewood from around the outside of buildings.
Limit access to buildings and remove hiding places by sealing cracks and other openings to the outside. Use door sweeps and weather stripping on doors and windows, and ensure screens are intact to prevent cockroaches from entering. Make sure seldom used plumbing fixtures, such as floor drains, have water in the p-trap or are otherwise blocked.
Trim shrubbery around buildings and clear leaf litter to increase light and air circulation. Locate and seal cracks in paved walkways, masonry features, and other hardscape crevices where cockroaches may hide.
Sticky traps placed indoors should be used to identify entry points and track cockroach populations. Cockroach sticky traps are available in garden and hardware stores. Place traps near exterior doors to catch Turkestan cockroaches attempting to enter the building. Look for cockroach hot spots near your home on warm, calm summer nights. Large populations may need to be controlled outside to minimize indoor invasions.
When using insecticides to manage Turkestan cockroaches, avoid using indoor foggers, “bombs”, or aerosol sprays; these products can be hazardous and may repel and disperse cockroaches to other areas without killing them. These products are meant for indoor use but remember that Turkestan cockroaches are outdoor species so indoor insecticide sprays will not provide long-term control. Sprays are not necessary if cleanup and removal of hiding places is combined with effective baits.
Bait stations containing granular or gel cockroach bait and placed near cockroach hiding areas can effectively control large populations. It may be 7 days or longer before you see fewer cockroaches. To control outdoor cockroaches, place baits in stations near known hot spots, irrigation or water meter boxes, in hardscape crevices, or under concrete slabs.
Turkestan cockroaches may inhabit storm drains and sewers. Never attempt any type of insecticide application or other treatment in public storm drains or sewers. Some sanitary sewer agencies may have a program for responding to cockroaches coming out of sewers. Contact your local agency for more information. Storm drains convey water and pollutants directly to local water bodies, so insecticide applications are not a viable option.
Don’t expect treatment of sewers to eliminate the problem. Residents must take steps to reduce populations on their property, and eliminate cockroach access points to their homes. Contact a pest control professional for very serious infestations on your property.
Visit the UC Statewide Integrated Pest Management website for more information on Turkestan and other cockroaches, as well as many other pests in and around the home, garden, landscape, and lawn.