Inspect sheets and pillows cases for flat, oval, reddish brown parasites about 1/4-inch long. These are adult bedbugs which are easier to detect than nymphs. When engorged with blood, bedbugs' bodies become larger and swollen and slightly easier to find.
Look for rusty-looking blood spots from a crushed, engorged bug. Bedbugs are good at hiding, so if you don't notice the bugs themselves or any blood spots, use a magnifying class to check for their droppings. Their fecal matter is black, about the size of pinhead. Bedbugs also leave behind pieces of sloughed off skin when they make their transformation from nymph to adult. These casings are nearly translucent and difficult to detect even with a magnifying glass.
Check the mattress and box spring for these same indicators. If there are rips, seams, tufts, or holes in the mattress or box spring, check there as well.
Examine areas close to where the bedbugs are biting, such as cracks and crevices near the headboard, footboard and mattress frame. If there is a night stand, phone, television, alarm clock, or anything else near the bed, check these areas as well. If there infestation in these areas, expand the area of your search to include carpeting, drapes, dressers and closets.