German cockroach is the one that matters most in Vancouver apartments and restaurant kitchens. It is small, tan, marked with two dark stripes behind the head, and it breeds indoors year-round. A single egg case carries roughly thirty to forty eggs, which is why an infestation that looked minor in spring can be severe by late summer.
Oriental cockroach is larger, near-black and slower. It prefers cool damp spaces, so in Vancouver it turns up in basements, crawlspaces, underground parkades and around floor drains rather than up in kitchens. It usually signals a moisture or drain problem as much as a pest problem.
American cockroach is the largest of the three, reddish-brown, and most often found in sewers, boiler rooms and commercial buildings with warm humid plant rooms.
The distinction is practical, not academic. German cockroach is treated with gel bait and growth regulators indoors and responds badly to sprays. Oriental cockroach is usually solved by fixing the damp and sealing the route in. Treating one as if it were the other is the most common reason a job fails.