Signs of Bed Bugs and Where They Hide

The clearest signs of bed bugs are clusters of small black or dark brown spots along mattress seams, rusty or reddish smears on sheets, pale translucent shed skins, tiny white eggs or eggshells, and live bugs hiding in seams and cracks near the bed. Most infestations start at the bed, so the head end of the mattress, the box spring and the bed frame are the first places to check.

Bites are not on this list for a reason. Bite reactions look like many other skin conditions, and some people do not react at all, so the EPA and CDC both advise confirming an infestation from the bugs or their signs, not from bites. If you need help identifying the insect itself, start with our bed bug identification guide.

Fecal spots

What they look like: Small, dark spots, black to dark reddish brown, roughly round or streaked. On fabric they bleed into the fibers like a dot from a felt-tip marker. They often appear in clusters along mattress piping, seams, labels and in cracks where bugs rest.

Why they appear: The spots are digested blood that bed bugs excrete after feeding. Clusters mark the places where bugs hide.

Look-alikes: Cockroach droppings can resemble bed bug spotting, but they are usually found in kitchens, bathrooms and cabinets rather than along mattress seams. Location is the best clue.

Blood smears

What they look like: Rusty, reddish or brownish streaks or smudges on sheets, pillowcases and mattress covers.

Why they appear: A bed bug that has just fed gets crushed when someone rolls over, or a bite seeps a little blood after the bug leaves. A few smears on their own are a weaker sign than fecal spotting, since small cuts and scratched bites can leave marks too.

Shed skins

What they look like: Empty, pale yellowish to tan, translucent skins in the shape of a bed bug, from a millimeter or two up to about 5 mm long. They are hollow and papery.

Why they appear: Nymphs molt five times before they become adults, leaving a skin behind each time. Skins tend to collect where bugs hide, so they help pinpoint a harborage. More skins in different sizes usually means a breeding population.

Eggs and eggshells

What they look like: Pearly white, about 1 mm long, about the size of a pinhead. Eggs are glued in place, often in crevices, seams, wood joints and on rough surfaces such as the underside of a box spring. Eggs older than about five days may show a dark eye spot. Hatched eggshells often stay glued in place after the nymph leaves.

Why they matter: Eggs confirm that bugs are breeding where you found them. They are hard to see on light fabrics, so use a bright flashlight and a magnifying glass.

Live bugs

What they look like: Adults are flat, oval, reddish brown and about 5 to 7 mm (3/16 to 1/4 inch) long, like an apple seed. Nymphs are smaller and pale yellowish unless recently fed, when they look red. Bugs are often found packed together in seams and cracks, mixed with spots, skins and eggs.

Why they matter: Finding a live bug is the surest confirmation. If you find one, keep it as a sample: press clear tape over it or put it in a small sealed bag or jar. An expert or your local extension office can confirm the species, which rules out look-alikes such as carpet beetles, fleas, and bat or swallow bugs.

Odor

What it smells like: A sweet, musty or sometimes sharp “buggy” smell.

Why it is unreliable: The odor is usually only noticeable in heavy infestations. The University of Kentucky advises against relying on smell for detection. A room without odor can still have bed bugs.

Room-by-room inspection checklist

Bed bugs hide in tight spaces near where people sleep or sit for long periods. The EPA notes that any crack that can hold a credit card can hide a bed bug, and the University of Kentucky describes their bodies as thin enough to fit in a gap about the width of a toothpick. Start with the bed and move outward.

The bed

• Mattress: Seams, piping, tufts, buttons, handles and the tag. Pay most attention to the head end and the corners. Lift the mattress and check the underside.
• Box spring: The top seams, piping, corners and tag, then the underside, including the wooden support boards and the screw and staple holes.
• Bed frame: Joints, screw holes, slats and the cracks where rails meet posts. Metal frames have hollow tubes and joints worth checking too.
• Headboard: Both sides, and especially the back and the gap where it meets the wall. Headboards mounted to the wall are a common hiding spot.
• Bedding: Folds of sheets, pillowcases, comforters and duvet covers, and the seams of pillows.

Near the bed

• Nightstands and dressers: Drawer joints, the underside, the back panel and the contents of drawers near the bed.
• Electrical outlets and switch plates: Bugs can hide behind cover plates. Turn off power before removing a plate.
• Baseboards and carpet edges: Especially along the wall behind the bed.
• Wall hangings and loose wallpaper: Behind picture frames, mirrors, peeling paint and loose wallpaper, and where the wall meets the ceiling in heavy infestations.
• Curtains: Folds and hems, especially those near the bed.
• Clocks, phones, lamps and other items on the nightstand.

Elsewhere

• Upholstered furniture: Couches, recliners and chairs where people nap or sit for long periods. Check seams, skirts, between cushions, under the frame and inside the dust cover.
• Luggage, backpacks and bags: Especially after travel. Check seams, pockets and zippers.
• Closets: Floor-level items, clothing piles and shoes near an infested bedroom.
• Adjacent rooms and units: In apartments, bugs can spread through wall voids and along pipes and wiring.

Tools that help

• A bright flashlight. Shine it at a low angle along seams and cracks so specks, skins and eggs stand out.
• An old credit card, putty knife or stiff card. Slide it along seams and into cracks to push bugs and eggs out into view.
• A magnifying glass or phone camera zoom for eggs, small nymphs and fecal spots.
• Clear tape or a small sealable bag for collecting specimens.
• Interceptor traps. These are dish-shaped cups placed under each bed leg. Bugs climbing up or down the legs fall into a smooth outer well and cannot climb out. They help detect light infestations and show whether bugs are still active after treatment. They work best when the bed is pulled a few inches away from the wall and no bedding touches the floor. The EPA notes that sticky traps alone do not work well for bed bugs.

What not to do

• Do not move furniture, bedding or belongings to another room before you have a plan. Sleeping on the couch or in another bedroom often moves bugs with you and spreads the infestation.
• Do not throw out mattresses or furniture right away. The EPA notes that most items can be treated and kept, and that discarding them is expensive and can spread bugs to other homes. If something must go, bag it or wrap it in plastic, mark it as infested or damage it so no one picks it up, and take it straight to the trash.
• Do not rely on foggers (“bug bombs”). The EPA says foggers should not be the sole method of bed bug control, because the spray does not reach bugs hiding in cracks and crevices. Using more than the space calls for can create an explosion risk. UC IPM and the University of Kentucky both advise against them.
• Use only products labeled for bed bugs, and do not apply pesticides to mattresses or bedding unless the product label allows it. Read and follow the label for any product you use.
• Do not use bleach, rubbing alcohol or lighters. The University of Kentucky warns that these are ineffective and can be dangerous, including as fire hazards.
• Do not diagnose from bites, and do not scratch them. Broken skin can become infected.

Next steps

Once you have found signs or a live bug:

1. Keep a sample of a bug or skin for identification.
2. Contain without scattering. Bag bedding and clothing from the room in plastic, carry them straight to the laundry, and run them through a hot dryer cycle. Vacuum mattress seams and the area around the bed, then seal the vacuum bag or contents in plastic and put it in an outdoor bin.
3. Install interceptors under bed legs and pull the bed away from the wall to start monitoring.
4. Tell your landlord or building manager if you rent, since neighboring units may need inspection.
5. Decide on a treatment plan. Most established infestations need several methods combined, and many need professional help.

Our bed bug treatment guide explains how heat, encasements, vacuuming and insecticides fit together and how to prepare a room. For help deciding whether to handle it yourself, see when to call a professional.