Among the family's distinctive characteristics are traumatic insemination, in which the male fertilises the eggs by piercing the female's abdominal wall with his intromittent organ.

They also have distinctive paired structures called mycetomes inside their bodies, in which they harbour bacterial symbionts: these may help them to obtain nutrients they cannot get from blood.

The American cliff swallow bug, Oeciacus vicarius, hibernates after mating in autumn and begins laying in spring, to coincide with the return of their migratory hosts.

[10] In a laboratory attempt to crossbreed a female C. lectularius with C. hemipterus males, one nymph hatched out of 479 eggs laid.

Host cues (at least in some species, including C. lectularius and Stricticimex antennatus) change from attractants to repellants after a cimicid has fed, causing it to move out of a danger zone after feeding.

The cimicids have no special adaptations to enable them to travel in this way, however the only two members of the Primicimicinae subfamily, Bucimex chilensis and Primicimex cavernis have claws and an erect a row of peg-like spines on the tarsus, and have been observed clinging to the bat's pelage with these.

Bats are social mammals and many species congregate in communal roosts to give birth and rear their young.

These roosts provide excellent conditions for their arthropod ectoparasites, with a steady temperature and opportunities for regular blood meals.

Cimicids lessen this risk by hiding in concealed locations between feeding bouts, and by producing a repellent substance which makes them distasteful.

[10] In evolutionary terms, most species of cimicid probably specialised on insectivorous bats or birds, with the possibility of dispersal to other sites via their winged hosts.

On returning to a roost, a bat may only be available to cimicids for a short time before it cools down and enters a state of torpor, with reduced blood flow.

Most cimicids have a preferred host, but accept some others when presented with the choice, such as C. lectularius and C. hemipterus, which are most often found among humans, but can also survive by feeding on birds, bats, rabbits, and mice.

[5] The effects of cimicid feeding on the host include causing an immune response that results in discomfort, the transmission of pathogens, secondary infections at the wound site, physiological changes such as iron deficiency, and reduced fitness (slow growth, small size, or lack of reproductive success).

Trypanosoma cruzi, the trypanosome that causes Chagas disease, is rarely transmitted from cimicids to bats, but it has not been observed replicating after such transmission.

[15] A fossil bedbug, Quasicimex eilapinastes, was identified in 2008 from Late Cretaceous Burmese amber, aged 99 million years ago (mya).

[16] Molecular analysis of five mitochondrial and nuclear genes shows that the Cimicidae, a group of over 100 species, form a clade.