mattresses, furniture, sofas, and hidden cracks. What Are Bed Bugs? Bed bugs are small, reddish-brown insects that feed on human blood. They usually hide in mattresses, bed frames, furniture, curtains, and wall cracks. Their bites can cause itching, skin irritation, and sleepless nights. Signs of a Bed Bug Infestation Red, itchy bite marks on the skin Small blood stains on bedsheets Dark spots or fecal stains on mattresses Musty odor near infested areas Live bed bugs found in furniture or bedding