Controlling Periodomestic Cockroaches

Peridomestic cockroaches include all of our common large cockroaches such as the American cockroach, but also some smaller species, such as the Asian cockroach.

When you find peridomestic cockroaches indoors, they usually came from outdoors. If the weather is warm, it's a good bet there are still cockroaches around, above or below the building, and new insects will continue to find their way inside.

Inspect Outdoors

In warm weather, indoor problems with peridomestic cockroaches should always trigger an outdoor inspection. Cockroaches may be in the landscape, on the building, in the loft, living in the drains or even up on the roof.

Peridomestic cockroaches often hide during the day on the building itself. They squeeze inside cracks and crevices on the outside walls, under the siding and in holes around pipes and wires. They leave at night to find food and water, and may travel inside.

You can drive cockroaches out of their hiding places using a short burst of a flushing agent. But flushing agents aren't very practical when inspecting a building's exterior. There are just too many potential hiding places. A better method is to inspect the exterior of the building one to two hours after sunset - prime time for large cockroaches to begin their search for food.

Spend an hour or so and look for cockroaches emerging from cracks and crevices. Note all of the locations and then treat active cracks and crevices. These gaps should then be sealed to prevent cockroaches from using these hiding places in the future.

Always inspect the landscape. Peridomestic cockroaches can reach high numbers in moist, shaded leaf litter under trees and shrubs. You may find up to 50 or more in a single rotting stump, a log, or in a planter next to a building. Don't limit your inspection to ground level.

1. Look up. Large cockroaches often congregate under roof overhangs. The roof gutter system is another prime inspection site, often ignored. Leaves and pine needles and other debris provide both food and shelter for large cockroaches.
2. Look down. Check cellars and pantries. Look inside water meter boxes. Be alert to the possibility of cockroaches in nearby sewers as hundreds of American cockroaches can live in a single sewer manhole or storm drain.

Habitat Modification

Ongoing problems with peridomestic cockroaches indoors often can be reduced or even eliminated by pest-proofing the building or modifying the cockroaches' habitat outdoors. Most of these tasks will be the homeowner's responsibility, including:

• Sealing cracks and crevices, holes in foundation walls, at windows, vents, doors, pipe/cable penetrations and soffits;
• Installing door sweeps, thresholds and weather seals on exterior doors and garage doors;
• Moving firewood, lumber and rubbish bins away from structures;
• Avoiding heavy mulch;
• Reducing moisture near foundations;
• Cleaning gutters;
• Keeping trees and shrubs trimmed, and making sure that no branches touch the building.

Article provided by Dynamic Pest Control