German cockroach
- Size
- 10 to 15 mm
- Colour
- Light brown with two dark stripes behind the head
- Wings
- Fully winged, but rarely fly
- Where
- Warm, humid places indoors: kitchens, behind fridges, dishwashers, cookers, in electrical equipment
- Breeding
- Very fast; a female carries an egg case of around 30 to 40 eggs
The German cockroach is the most common cockroach in London's flats, restaurants and takeaways. It loves warmth and hides in tiny cracks close to food and water, often inside appliances. Infestations grow fast and spread between connected flats.
Oriental cockroach
- Size
- 20 to 25 mm
- Colour
- Dark brown to black and shiny
- Wings
- Males have short wings, females have stubs; neither fly
- Where
- Cooler, damp places: basements, drains, under floors, around pipes and bin stores
- Breeding
- Slower than German cockroaches; egg cases are dropped in sheltered places
Oriental cockroaches, sometimes called black beetles, are bigger, slower and prefer cooler, damp areas. They often come up from drains and basements and are seen on ground floors and in older buildings.
Why species matters
German cockroaches are treated with gel baits and insecticides placed deep in cracks and appliances, with several follow-ups because they breed so quickly. Oriental cockroaches need treatment in damp areas, drains and voids, and proofing of entry points from outside and from drains.
Signs of cockroaches
- Live cockroaches, especially at night when you switch on the light
- Droppings like ground pepper (German) or small cylinders (Oriental)
- Egg cases in cracks and behind appliances
- Brown smear marks and an unpleasant, musty smell
- Shed skins
Questions and answers
Do cockroaches mean my home is dirty?
Not necessarily. In blocks of flats they travel through ducts and pipework from other flats, whatever your standard of cleanliness.
Can I get rid of cockroaches myself?
Small numbers can sometimes be controlled with shop baits, but most infestations need professional treatment and follow-ups.
Do cockroaches spread disease?
They can carry bacteria that cause food poisoning and can trigger asthma and allergies.
Related pages
This page is general information, last reviewed on 19 October 2026. It is not a substitute for an on-site inspection.