Cockroaches are an ancient group of insects that have remained relatively unchanged for the past 400 million years. They are among the most common pests in many homes and other buildings. At night they search for food in kitchens, food storage places, rubbish bins, drains and sewers. They are pests because of their filthy habits and bad smell.Cockroaches can sometimes play a role as carriers of intestinal diseases, such as diarrhoea, dysentery, typhoid fever and cholera