They are small nocturnal insects of the family Cimicidae that live by hematophagy, that is by feeding on the blood of humans and other warm-blooded hosts.

Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species - more than half of all known living organisms with published estimates of undescribed species as high as 30 million, thus potentially representing over 90% of the life forms on the planet.Insects may be found in nearly all environments on the planet, although only a small number of species occur in the oceans where crustaceans tend to predominate instead. There are approximately 5,000 dragonfly species, 2,000 praying mantis, 20,000 grasshopper, 170,000 butterfly and moth, 120,000 fly, 82,000 true bug, 360,000 beetle, and 110,000 bee, wasp and ant species described to date. Estimates of the total number of current species, including those not yet known to science, range from two million to fifty million, with newer studies favouring a lower figure of about six to ten million