All Cimex organisms are red-brown colored insects. Cimex lectularius are 5-7 mm in size. Females are slightly larger than males. Females deposit fertilized eggs in cracks or crevices, with newborns emerging in 4-5 days. The mechanism of skin injury by arthropods depends on the structure of the mouthparts.
Some patients show a severe systemic hypersensitivity to arthropod allergens.
Bedbugs are 5-7 mm in length with reduced wings. The mouthparts are modified for piercing and sucking. They live between wooden floorboards or in furniture, bed frames, mattresses, or behind peeling paint. Bedbugs normally feed at night, usually about an hour before dawn, but if the conditions are favorable, they also feed during the day. Feeding time takes from 3-12 minutes.