German or Oriental? Telling Them Apart

The quick version

Warm and High, or Cool and Low

Before any detail: where you are finding them settles it most of the time.

Warm places, and found high as well as low — behind and above the fridge, inside the microwave housing, around the boiler, at the top of a unit — is a German cockroach.

Cool, damp places low down — a drain, a gully, a cellar, a bathroom floor, under a ground-floor unit, an external manhole — is an Oriental.

That single distinction gets it right far more often than people expect, and it is available to you before anyone arrives.

Photographs on this page are for illustration purposes only.

The German cockroach

Small, Tan, Two Stripes

About 12 to 15mm long as an adult, so noticeably under an inch. Light tan to mid-brown. The identifying feature is on the pronotum, the shield behind the head: two dark, roughly parallel stripes running front to back. Nothing else here has them.

Wings are present in the adult and cover the abdomen, but they barely fly — expect fast running rather than flight. Nymphs are much smaller and darker, almost black, with a pale band, and are often mistaken for a different insect entirely.

This is the species that matters. It breeds fastest, it is the most insecticide-resistant of the three, and it is the one behind almost every serious commercial infestation.

The Oriental cockroach

Larger, Very Dark, Ground Level

20 to 30mm and much darker — deep brown to nearly black, with a glossy, almost varnished look. No stripes on the pronotum.

The female's wings are reduced to stubs and the male's do not reach the end of the abdomen, so neither flies. They are slower and clumsier-looking than a German, and they cannot climb smooth vertical surfaces nearly as well, which is why you find them on floors and in baths rather than up on a worktop.

They want cool and damp. Drains, gullies, cellars, under paths, ducting, the void under a ground floor. Outdoors in summer, pushing indoors as it gets cold.

The American cockroach

The Big One

35 to 40mm, reddish-brown, with a pale yellowish margin around the pronotum. Much less common in domestic property here. Associated with drains, ducting, and heated commercial buildings — and it does fly, or at least glides, which people find memorable.

If you have something that looks far too big to be a UK cockroach, it is probably this one.

Why it matters

Same Word, Different Job

The species changes where the treatment goes, which is the whole point of establishing it first.

German means the treatment concentrates on the warm interior of units and appliances, high and low, and it means resistance is a live concern so the choice of product and the avoidance of repellents matters enormously.

Oriental means looking outside and below — drains, gullies, the perimeter, the void under the floor — because the population is frequently not indoors at all. Treating the kitchen for an Oriental problem that is living in a drain is money spent in the wrong place.

Take a photograph if you can. Size against something familiar, and a view of the shield behind the head, settles it.

Short answers

Cockroach Questions

Going further

Cockroach Guides