These bloodsucking insects possess mouthparts that are adapted to pierce and then suck blood. The bottom lip, known as the labium, is modified and forms a ‘grooved sheath’ that receives two sets of bristle like stylets. These stylets are the modified maxillae & mandibles.
Some people think that they are (Cimex electuaries) too small and cannot be seen with the naked eye very easily. This is untrue because the adult bug is about the size of an apple seed. However, after it feeds, it could grow up to three times its usual size. It also turns a reddish brown color following a feeding.