German Cockroach

Where it lives

Kitchens and bathrooms: behind fridges and ovens, inside motor housings, under sinks, in cupboard hinges, behind loose tiles and inside cardboard packaging. Hides within a few metres of food and water.

Signs

• Live insects scattering when a light is switched on at night
• Black pepper-like droppings in drawers, cupboard corners and hinges
• A distinctive musty, oily smell in badly infested kitchens
• Brown 8 mm egg cases (ootheca) glued into cracks
• Shed skins in cupboard runners and behind appliances
• Live nymphs in the morning, which usually means the population has outgrown its harbourage

Risks

• Carries Salmonella, E. coli, Listeria and Staphylococcus on its body
• Droppings and shed skins are a major trigger for asthma and allergies in children
• Contaminates food, packaging and preparation surfaces
• Causes food business closures and failed inspections
• Populations develop resistance to over-the-counter sprays
• Neighbouring flats become re-infestation sources, so one unit alone is rarely a fix

Prevention

• Deep clean grease from behind and beneath cookers and fridges
• Never leave washing-up, pet food or bin bags out overnight
• Break down and remove cardboard boxes, a favourite harbourage and a common way roaches arrive
• Repair dripping taps and seal gaps behind tiles and around pipework
• Inspect second-hand appliances and deliveries before bringing them in
• Do not use aerosol sprays anywhere near a gel bait placement, they contaminate it and the roaches stop feeding
• In a block, tell the neighbours. One treated flat next to two untreated ones just moves the population around

Treatment

Professional control is based on non-repellent gel bait applied in dozens of small placements at harbourage points, supported by insect growth regulators to break the breeding cycle and sticky monitors to measure progress. Aerosol sprays are avoided because they repel cockroaches deeper into voids. Expect two visits 14 days apart, with monitoring for a further month.