Bed bugs: Bed bugs are small, oval, wingless insects of the family Cimicidae, which have a flat, reddish-brown body and feed on human and animal blood. Bed bugs are active at night and bite any areas of exposed skin. Bed bugs can infest a home and hide in crevices or cracks around beds or furniture. While some bites may go unnoticed, bed bug bites may also result in localized swelling and itching, and the areas may become inflamed or infected when scratched. Bed bugs are not believed to transmit diseases to humans.