There are two main species of cockroach in Britain, Oriental and German Cockroaches.
Cockroaches are distinguished by their very long whip-like antennae, flat oval bodies and rapid, jerky walk. The adult German Cockroach is a light yellowy/brown and is 10 to 15mm long. The Oriental Cockroach is dark brown/black and is 20 to 24mm long. Immature stages of Cockroach, look exactly like adults, just on a smaller scale.
The German Cockroach carries its egg case, until the 30 or more nymphs are ready to hatch. The Oriental Cockroach deposits its 13mm long egg capsule on packaging, sacking or in suitable dark crevices, before the 16 to 18 nymphs hatch around 12 weeks later. They grow in stages, from nymphs to maturity in 6 to 12 months for the Oriental Cockroach, and 6 to 12 weeks for the German Cockroach.
Cockroaches are rarely able to survive out of doors in the British climate, but thrive around the heating ducts and boiler rooms of large centrally heated buildings e.g. hospitals, bakeries, hotels and restaurant kitchens, and blocks of flats. They cluster around pipes, stoves, and sinks, especially in humid areas, and will often remain hidden during the day.
Cockroaches will feed on almost anything, including refuse, faecal matter and food for consumption. They also require access to water, and will be generally found in inaccessible harbourages, close to water and food. Cockroaches can survive for several months without food, but will not live for more than a few days without water.