I think I’ve spotted a couple of cockroaches in my kitchen late at night. They were about an inch long. I’m terrified. What do I do? I recently bought a secondhand fridge - do you think they came into the house that way? AN, by e-mail

There are two common species of cockroach in Britain - the Oriental cockroach (between 20 and 25mm long) and the German cockroach (10mm-15mm long). Both require constant high temperatures to thrive, so, in this country, they are usually restricted to institutions and commercial premises. The exception is community housing, where centralised heating and hot-water systems can create favourable conditions for the insects, which then spread along ducting and into individual dwellings.

The description you provide does sound like cockroaches. The size is right, and they are nocturnal, concealing themselves in warm crevices during the day. Refrigerator motors have a reputation as excellent haunts - running constantly, they are warm, dark and undisturbed. If the fridge comes from a commercial kitchen or from affected housing, there is a strong possibility that cockroaches could have travelled with it.

Now that the bugs are in cooler surroundings, the problem may well resolve itself, and they may not be able to spread beyond the source of heat. It’s a good idea to confirm that the insects are indeed cockroaches. Monitor traps are inexpensive. A bait lures the insects onto a sticky pad. They can then be checked against photos on the internet or sent for identification. Traps can remedy small infestations. They should be left in position for about six weeks after you have trapped the last cockroach, as eggs can hatch some time afterwards.

A fridge motor is difficult to treat. Water-based sprays should not be used near electrical equipment and insecticide dusts are likely to be blown out of the motor by the cooling fan, possibly contaminating exposed food-preparation surfaces. Cockroach baits can be purchased; these should be used in accordance with the manufacturer’s instructions.

If the problem has spread, consider calling in a professional. For details of local companies, visit the website of the British Pest Control Association (www.bpca.org.uk ).

Richard Strand runs Pest Information Consultancy; www.pestfreehome.co.uk

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