German cockroach Blattella germanica
- Size
- 10 to 15 mm
- Markings
- Light brown to dark brown, with two dark parallel stripes on the shield behind the head. The young are darker, wingless, with the same stripes.
- Where
- Kitchens and bathrooms most of all: behind the ref and the stove, in cabinet hinges, inside appliances.
- Indoors or out
- Lives and breeds indoors. The female carries her egg case, 30 to 40 eggs, until just before they hatch, so numbers climb fast.
- What to do
- Baits placed on their runs, with sanitation and sealed cracks. This is the one that turns into an infestation.
Brownbanded cockroach Supella longipalpa
- Size
- 13 to 14.5 mm
- Markings
- Dark brown with two pale-brown bands across the wings. Often mistaken for the German cockroach because of its size.
- Where
- Away from the kitchen: bedrooms, furniture and closets, especially high shelves and behind picture frames.
- Indoors or out
- Lives indoors. The females glue their egg cases to furniture and other surfaces around the house.
- What to do
- Look high and in the bedroom, not only the kitchen. Treatment follows where the egg cases are.
Australian cockroach Periplaneta australasiae
- Size
- 32 to 35 mm
- Markings
- Reddish-brown to dark brown with a light-yellow band along the outer edge of each wing near the body. That band is how to tell it from the American cockroach.
- Where
- Mostly outdoors: under bark, in woodpiles, in plants and other damp places. It can come inside.
- Indoors or out
- An outdoor cockroach that wanders in. Outdoor cockroaches do not survive well indoors.
- What to do
- Clear woodpiles and damp debris from the walls and seal gaps at ground level.
American cockroach Periplaneta americana
- Size
- About 4 cm on average, the largest of the common ones
- Markings
- Reddish-brown with a pale brown or yellow band round the edge of the shield behind the head.
- Where
- Sewers, drains, basements and damp, shady places outside, coming up into the house through drains and gaps.
- Indoors or out
- Breeds mainly outside the living space and comes in from there.
- What to do
- Cover floor drains, seal gaps where pipes pass through walls, and reduce damp. Baits work well against them.