The common bed bug is a small brown insect that lacks functional wings and has a 3-segmented beak. Bed bug bites are similar to flea bites except that a red area does not occur in the center. Many people show an immediate response to bed bug bites in the form of a large inflamed spot or swelling called a wheal. Common bed bugs can be naturally infested with at least 27 different human pathogens, but there is little evidence that they transmit any of these to man.