In late May and June, we get calls from homeowners who suddenly have cockroaches in their homes. Large, brown, flying cockroaches that are freaking them out. When cockroaches appear indoors at this time of year where there have been no cockroaches before, it’s a good bet that it’s the Pennsylvania wood cockroach, especially if we’re talking about a single-family home on a wooded lot.

The good news is that the Pennsylvania wood roach is a temporary indoor pest. It doesn’t mean that you have an ongoing cockroach infestation in your home. In fact, wood cockroaches don’t survive long in the drier indoor air. The wood roach is an outdoor insect, common in wooded areas where it feeds on decaying organic matter. It really doesn’t have any interest in being in your home…unless there’s a female wood cockroach inside.

The reason for the activity at this time of year is that May-June is breeding season for the wood cockroach. The male roach is strongly attracted to pheromones from the female roach. If a female roach gets inside, male wood roaches will follow. The male wood cockroach is brown with the edges of the wings lighter, and is about one inch long. The male has long wings and flies readily. The smaller female has short wing pads and does not fly; you will probably never see her. The dark female wood roach and the reddish-brown nymphs look very much like the oriental cockroach, which can reproduce indoors. You may need an expert to tell the difference.

Wood cockroaches usually end up inside when they are first attracted to outdoor lights. During mating season, groups of males often fly to lights at night. They may just wander inside through cracks and crevices, or the males may be lured inside by the pheromones of a female. They also sometimes end up inside when they are carried in on firewood in which they are hiding. Once inside, male wood roaches are inactive during the day but may fly to lights at night. Outside the home, wood roaches can sometimes be found under cedar shake or other wood siding, in gutters, in potted plants, or in firewood.

To keep wood cockroaches outside where they belong, reduce outdoor lighting, especially around doors and windows. Check for openings where the roaches may be entering: tighten screens, screen vents, and make sure doors have thresholds or sweeps. Garage doors are a frequent entry point for wood cockroaches. Keep piles of mulch and leaf litter away from the house, and don’t store firewood indoors.