You wake up with itchy welts that are not present when you went to bed. You can get bloodstains on your pillows or sheets. Bedbug excrement can be found on walls, sheets, mattresses and bedclothes appearing as dark or rusty spots. In areas where bedbugs are present, you may find eggshells or fecal spots as well as shed skins. A musty, offensive odor originating from the bug’s scent glands