They are parasitic insects infecting mankind for more than 3500 years. There are at least 92 known species all around the world. The most common species is lectularius Cimex, which is better adapted to human environment. Bed bugs inject their victims with their saliva, which contains a numbing agent, like Novocain. They drink until they become engorged with a person's blood - crawling away satisfied - until the next night. The bed bugs are an insect of nocturnal habits. Feeding on blood by night and hiding away in various parts of the room by day.