Oriental cockroaches

What Oriental cockroaches look like

Oriental cockroaches are dark, almost black, with a smooth glossy shell that looks oily under a light. Adults run about 20 to 30 mm, smaller than an American cockroach but much heavier looking than a German one. The sexes differ enough to confuse people. Males have wings that cover about three quarters of the body, while females have only short wing pads and look wingless. Neither one flies. They are also poor climbers on smooth vertical surfaces, so they tend to stay at floor level, in sinks, tubs and window wells they cannot get back out of. Young ones are dark reddish brown and wingless. This is the species most often described simply as a black beetle in the basement.

Signs you have Oriental cockroaches

• Dark roaches at floor level in basements, crawl spaces, laundry rooms or along the base of foundation walls.
• Insects trapped in sinks and tubs, because they climb in and cannot climb back up the smooth sides.
• A strong musty smell in a damp basement or crawl space, stronger than the odour of most other cockroaches.
• Egg cases about 10 mm long, dark and slightly swollen, dropped in sheltered spots rather than carried around.
• Activity around drains and sump pits, especially where a floor drain has dried out or a cover is broken.

Why Oriental cockroaches come indoors

Unlike most cockroaches, this one prefers cool and damp over warm and dry. It lives outdoors under mulch, leaf litter, stones, flower boxes and the edges of paving, and it moves into buildings through foundation cracks, window wells, air bricks, crawl space vents and gaps under exterior doors. Once inside it stays low, in basements, crawl spaces, service tunnels and around drains, where moisture collects. Numbers often rise after heavy rain or during a dry spell, when the outdoor shelter it was using stops working. Buildings with damp basements, blocked eavestroughs or soil grading that sends water toward the foundation see it most.

How to keep Oriental cockroaches out

• Deal with the damp first. Fix leaks, improve basement ventilation and grade soil so water runs away from the foundation.
• Seal foundation cracks, gaps around service entries, and openings into crawl spaces and window wells.
• Fit tight sweeps on exterior and basement doors, and screen air bricks and crawl space vents.
• Pull mulch, leaf litter, firewood and planters back from the wall of the building.
• Keep floor drains filled and covered, and clear standing water around sump pits and laundry areas.

How GO! Pest Control treats Oriental cockroaches

• Inspection. We check basements, crawl spaces, drains and the ground outside to find the damp harbourage they are using.
• Treatment. We treat the harbourage and the routes in, including foundation level entry points, rather than just the rooms where you see them.
• Follow-up. We come back to confirm the activity has dropped and to treat again if outdoor pressure is still pushing them in.
• Advice. We point out the moisture and grading issues that keep bringing them back, and what to change first.

We are licensed, insured and bonded, and we work in homes, apartments, condos and businesses across the Toronto GTA, Ottawa and Hamilton.

Common questions about Oriental cockroaches