Wood cockroaches live under loose bark, in cavities of fallen or dying trees, or in stumps. They are natives of moist woodland habitats where they feed on decaying organic matter.
These cockroaches are accidental invaders in homes and buildings located in and around wooded areas. They are especially active during their summer mating season. Winged males can fly short distances; lights can draw large numbers of them to homes and structures. They can get inside a number of ways—by crawling under exterior door gaps or through open windows, gaps around pipe or electrical service, or other cracks and crevices.
While it looks like a “typical” cockroach, the wood cockroach (Figure 1) has a pale, light white or transparent margin on the outer edge on the thorax. It behaves differently from the house-infesting species. Wood cockroaches are not secretive; they are active day and night and usually don’t run when approached. They will wander about the house without congregating in any particular location, like a kitchen or bathroom. They are an annoyance, but wood cockroaches do not become established indoor pests because the air is too dry for them to survive for long.
While there can be many of them, they are a temporary problem so there is no need for extensive use of insecticides in the home. Cockroaches found indoors can be swatted and discarded, or sprayed with an aerosol insecticide containing pyrethrins .
The following steps may be helpful if wood cockroaches are a chronic problem:
- Wood cockroaches prefer quiet, undisturbed moist areas out-of-doors, such as heavily mulched or naturalized areas or stacked firewood. Reducing clutter and increasing light and air penetration makes these places less attractive for the insect.
- Install tight-fitting window screens and door sweeps to exclude wandering cockroaches and other insects. Sticky card mouse/insect traps can be placed in these areas to trap wandering cockroaches near entry doors.
- Males are attracted to lights at night; limiting light use, especially around exterior doors, might be of some benefit.
- In severe cases, insecticides can be applied as a “barrier treatment” around the base of the foundation. Pay particular attention to door thresholds, garage and crawl space entrances, and foundation vents. Example pesticides include carbaryl (Sevin), or any of the pyrethroid insecticides, such as bifenthrin (Ortho Home Defense Perimeter and Indoor Insect Killer), cyfluthrin (Bayer Advanced Home Pest Control Indoor & Outdoor Insect Killer), or permethrin (Spectracide Bug Stop).
By Lee Townsend, Extension Entomologist