The adult German cockroach is 10 to 15mm long. The Common or Oriental cockroach is 20 to 24mm long. They find it difficult to survive out of doors in the British climate, which makes them a pest. They thrive around the heating ducts and boiler rooms of large centrally heated buildings e.g. hospitals, bakeries, hotel and restaurant kitchens, laundries and blocks of flats. They cluster around pipes, stoves, and sinks, especially in humid areas.
The German cockroach carries its egg case, a small brown purse-like capsule, until the 30 or more nymphs are ready to hatch from it. The Oriental cockroach deposits its 13mm long egg capsule on packaging, sacking or in suitable dark crevices before the 16 or 18 nymphs hatch out.
Cockroaches will eat any type of food and are mainly nocturnal. They travel from their inaccessible harbourages to feed, contaminating food and food utensils and food preparation areas as they move – hence the need for cockroach pest control.
Cockroaches taint food with an unpleasant odour and can carry of various diseases, including serious food poisoning