Cockroaches are not just a summer pest: how to keep them out all year

Because cockroaches love warmth, many people think of them as a summer problem. Indoors, that is not how it works. A centrally heated home, a warm kitchen or a heated block of flats gives them the conditions they need in every month of the year, so it pays to keep them out in winter as much as in summer.

01What cockroaches need

• Warmth. German cockroaches in particular cluster around heat: behind fridges and cookers, inside motor housings, near boilers and along hot water pipes.
• Water. Cockroaches can go weeks without food, but they need water regularly. Dripping taps, leaks under sinks, condensation and damp cellars all help them.
• Food. They are not fussy. Crumbs, grease, pet food, food waste, packaging, paper and rubbish will all do.
• Shelter. Cracks, gaps around pipes, the spaces behind kitchen units and under appliances, and drains and ducts. Oriental cockroaches favour cooler, damper places such as cellars and under floors.

02How cockroaches get in

Cockroaches are often carried in, hidden in deliveries, cardboard boxes, second-hand appliances and furniture. They also move through buildings along pipe and cable runs, service ducts and drains, which is why flats and terraced houses can be affected by a neighbour's problem. Oriental cockroaches can come up from drains and in under doors at ground level.

03How to keep them out

• Seal gaps around pipes, cables and skirting boards, and fill cracks in walls and floors, particularly in kitchens and bathrooms.
• Fix leaks and dripping taps, and keep areas under sinks dry.
• Do not leave food out. Cover food on worktops and store dry food in sealed glass or plastic containers.
• Wash up before bed. Do not leave dirty dishes or pans in the sink overnight, when cockroaches are most active.
• Pick up pet food bowls at night.
• Use a lidded bin and empty it regularly.
• Clean behind and under appliances now and then, where grease and crumbs build up unseen.
• Check deliveries and second-hand items before you bring them into the kitchen, and do not store cardboard boxes there.
• Keep drains in good order, with covers and gratings intact.

04Signs they are already there

• Cockroaches seen at night, often running for cover when a light goes on.
• Small dark droppings like ground coffee, or dark smear marks, near where they shelter.
• Shed skins and brown, purse-shaped egg cases in cracks and behind appliances.
• An unpleasant musty, oily smell.

Our guide to cockroach infestations covers identifying the species, the health risks and why they are hard to clear. If what you have seen is a large brown beetle flying into a lit window in spring, read our guide to cockchafers first. They are often mistaken for cockroaches and are harmless.