German Cockroach

Blattella germanica

German Cockroach

Blattella germanica

Take care

Handle with care

It does not bite in any meaningful sense. The reason to take it seriously is different: established populations are a recognised trigger for asthma and allergy, particularly in children, through shed skins and droppings rather than through contact.

We identify, we don't diagnose. If you've been bitten or stung and symptoms develop, or you're worried, seek medical attention.

Size13–16 mm

MarkingsTwo dark parallel stripes on the plate behind the head — the decisive mark · Small: 13–16 mm, far smaller than an American cockroach

WhereInside kitchen and bathroom cabinetry — behind fridges, under sinks, inside appliance housings and along the warm side of pipework.

How to tell it apart

Two dark parallel stripes on the plate behind the head — the decisive mark
Small: 13–16 mm, far smaller than an American cockroach
Tan to light brown, with wings that cover the abdomen but are barely used
Nymphs are near-black with the same two stripes, and wingless
Almost always in kitchens and bathrooms, close to warmth and water

Where you’ll find it

Across the entire United States. It is the cockroach that actually infests buildings, and it lives indoors year-round rather than wandering in.

Inside kitchen and bathroom cabinetry — behind fridges, under sinks, inside appliance housings and along the warm side of pipework.

How it behaves

This is the species that establishes rather than visits, and the reason is reproductive. The female carries her egg case until it is nearly ready to hatch, so far fewer eggs are lost, and a population can double quickly from a very small start. They stay within a short distance of food and water and are strongly thigmotactic — they want to be touching a surface on both sides, which is why they live in cracks and behind panels rather than in the open.

You’ve found one indoors

Finding nymphs matters more than finding adults: nymphs mean breeding on site rather than one animal carried in on a bag or a box. Sanitation and sealing harbourage do most of the work, and gel baits are the standard treatment. This is one of the few species on this site where professional treatment is usually the right call, because a partial job leaves a population that recovers.

Common questions

Do German cockroaches bite?

Effectively no. Bites are vanishingly rare and not the reason they matter. The health concern is allergen exposure from droppings and shed skins in an established infestation.

How do I know it is this species?

Two dark parallel stripes running back from the head, and small size. An American cockroach is three times the length and has a pale figure-of-eight rather than stripes.

Does finding one mean I have an infestation?

Not necessarily, but finding nymphs does. A single adult can arrive in a delivery. Wingless striped juveniles mean they are breeding where you found them.

Are they a sign the house is dirty?

No. They need warmth, moisture and any food residue at all, and they arrive in packaging and second-hand appliances. Clean homes get them.

Commonly confused with

Brown-banded Cockroach Take care

Keep identifying

Identify another animal from a photo or return to the Cockroaches guide.

Next: Brown-banded Cockroach

Where this was checked

iNaturalist — Blattella germanica checked 2026-07-30

Last reviewed 2026-07-30. We identify, we don’t diagnose — what we can and can’t tell you.