Signs of Bed Bugs and How to Check for Them

Waking up with itchy bites is unsettling, but bites alone can't tell you whether you have bed bugs. To know for sure, you need to find evidence the bugs leave behind. This guide shows you what bed bug signs look like, exactly where and how to check, and what to do if you find something.

The 6 Signs of Bed Bugs

1. Dark spots (bed bug droppings)

Bed bug droppings are digested blood, so they look like tiny black or dark brown dots about the size of a period, often in groups.^1,7,8 On fabric they soak in and spread a little, like a dot from a marker. On wood or other hard surfaces they sit as small, smooth dark spots.^1,9 To test a spot, wipe it with a damp cloth or tissue. Bed bug droppings smear and leave a rusty color.^5,10 German cockroach droppings, by contrast, feel gritty.⁸

2. Rusty or reddish stains on sheets

Small rust-colored stains on sheets, pillowcases or the mattress come from crushed bugs or from blood that bed bugs pass while feeding.^1,2

3. Live bugs

Adult bed bugs are reddish-brown, flat, oval and wingless, about 3/16 to 1/4 inch long (5 to 7 mm), or about the size of an apple seed. After feeding they swell up and turn redder.^11,8 Young bed bugs (nymphs) range from about 1.5 mm to 4.5 mm and are pale or straw-colored until they feed, so the smallest ones are hard to see.^11,8,3 Bed bugs can't fly or jump.^3,9

4. Eggs and eggshells

Bed bug eggs are about 1 mm long, the size of a pinhead, pearly white and slightly curved. After about 5 days, a red eye spot shows through the shell.^11,8,4,5 Eggs are glued in place, and the empty shells often stay stuck after hatching.^3,4 Shining a flashlight at a low angle along the surface makes them easier to spot.⁵

5. Shed skins

Young bed bugs shed their skin five times on the way to adulthood, leaving behind light tan, empty shells in several sizes.^3,4,8 Because a nymph must feed before each molt, finding skins in several sizes means bed bugs have been feeding and growing in your home, not just passing through.^8,4

6. A sweet, musty odor

Heavy infestations can give off a sweet, musty smell.^2,7 Don't count on your nose, though: a University of Kentucky entomologist notes the odor is seldom noticeable except in extreme infestations and shouldn't be relied on.³

Early Signs of a Light Infestation

Early on, the evidence is easy to miss. There may be only one or two dark spots in any one place, and the youngest bugs are nearly invisible.^8,11 In one study, careful visual inspections found only half of very light infestations.⁶ Watch for:

• A few tiny dark dots or rusty specks on your sheets or along a mattress seam.^1,7
• A single bug or shed skin near the mattress tag, piping or headboard.^1,8
• Itchy bites that keep appearing after you sleep.²

Early infestations usually stay close to beds and sofas before spreading.³ Make a habit of checking the mattress seams each time you change the sheets.^1,9

What Bites Can (and Can't) Tell You

The EPA calls bites "a poor indicator" of bed bugs.¹ Bed bug bites look like mosquito bites, chigger bites, rashes or hives, and you won't feel them, because the bugs inject a numbing agent as they feed.^1,2 Marks can take up to 14 days to appear, and about 30% of people don't react at all.^2,3

• What they look like: red, swollen, itchy bumps, often with a darker red center. On Black or brown skin, bites may look brown, red or purple and be harder to see.^2,12,13
• Pattern: bites often show up in a line, zigzag or small cluster (sometimes called "breakfast, lunch and dinner"), but flea bites can look the same, and many bed bug bites are scattered.^2,14,15
• Where: on skin exposed while you sleep, such as the face, neck, arms, hands, shoulders and legs. Flea bites, by contrast, tend to cluster around the ankles.^2,3

See our bed bug bites guide for pictures and treatment.

How to Check for Bed Bugs, Step by Step

What you need: a bright flashlight, a magnifying glass, a thin card or putty knife to probe seams, gloves, and clear tape or a zip bag for any bugs you find.^7,5,4,16 An inexpensive bed bug inspection kit (we earn a small commission) bundles these.

Start at the bed and work outward. About 85% of bed bugs are in or near the bed, and the CDC says they tend to live within about 8 feet of where people sleep.^4,2

1. Strip the bed. Remove the sheets and check the mattress seams, piping, tags and tufts, especially at the head of the bed.^7,1
2. Check the box spring. Look at the seams and underside, and pull back the thin fabric dust cover underneath to check the wooden frame.^3,5,8
3. Inspect the bed frame and headboard. Look into joints, cracks and screw holes, and behind the headboard.^1,8
4. Check nightstands and dressers. Pull out drawers and look at the joints, corners and undersides.^7,1
5. Check upholstered chairs and couches. Look along seams and tufts and under the cushions.^1,7
6. Check curtains. Look in folds, pleats and the seams near the rod.^1,8
7. Work around the room. Check baseboards and carpet edges, outlet and switch plates, behind pictures, loose wallpaper and the corner where the wall meets the ceiling.^1,8,7
8. Check clutter. Look at items stored under the bed, books, stuffed animals, electronics and picture frames.^8,3

In heavy infestations, bugs, droppings, skins and eggs gather in clusters that can look like mold or mildew on a ceiling or wall.⁸

Checking Couches and Hotel Rooms

Couches: remove the cushions and check seams, tufts, zippers and the crevices underneath. Sofas used for sleeping are a common hiding place.^1,7,3

Hotel rooms: before unpacking, put your luggage in the bathroom or on the luggage rack (after checking the rack). Pull back the sheets at the head of the bed and check the mattress seams and corners, then look behind the headboard and in any upholstered chairs.^17,18,19 If you find signs, ask for a room that isn't next to, above or below the one you're in.¹⁸ When you get home, unpack straight into the washer and run your clothes through a hot dryer.¹⁷ See our bed bug travel tips.

Traps, Monitors and Dogs

• Interceptor cups: cups placed under each bed and couch leg catch bugs climbing up or down. In a study of apartments, they found 70% of very light infestations, compared with 50% for visual inspection, and 100% of somewhat larger ones.⁶ Pull the bed away from the wall and keep bedding off the floor so the cups are the only way up.²⁰ Check them every week or two.²¹ See our bed bug traps guide.
• Carbon dioxide monitors: some traps use carbon dioxide, which bed bugs follow to find people.^22,23 In the same apartment study, a homemade dry-ice trap caught bugs in 60% of very light infestations in a single day, while commercial carbon dioxide monitors caught 10% to 50%.⁶
• Dogs: trained dogs can help, but accuracy varies widely. In real-world tests of 11 commercial teams, dogs found bed bugs 44% of the time on average and gave false alerts 15% of the time.²⁴ Ask the company to confirm any alert with a detailed inspection before treating.^4,25

An empty trap doesn't prove you're bed bug-free, so keep checking.²⁵

Bugs That Look Like Bed Bugs

No Signs, but Still Itching?

You're not imagining the stress. In a small study of 91 Montreal tenants, those living with bed bugs were significantly more likely to report anxiety symptoms and sleep problems than neighbors without them.³¹ That worry can make every itch feel like a bite. If you've checked carefully and found nothing:

• Put interceptor cups under the bed legs for one to two weeks.^6,21
• Save anything you find on clear tape or in a sealed bag and have it identified. Your county extension office can often help, and the Cornell Insect Diagnostic Lab identifies mailed samples for a fee. Photos of bites generally don't help identify the cause.^10,16
• If repeated checks find nothing and you're still itching, see a doctor.³² Dry skin, skin conditions such as eczema, bites from other pests, reactions to soaps or medicines and other health problems can all cause itching.³³ Our guide to itching in bed with no bugs explains the possibilities.

What to Do If You Find Bed Bugs

• Don't switch beds. Sleeping on the couch or in another room can spread bed bugs to new areas of your home.³⁴
• Don't grab a bug bomb. Foggers don't reach bed bugs where they hide, and their repellent ingredients can drive insects deeper into walls and crevices.^20,35
• Bag and dry your bedding. Run sheets and clothes through a dryer on high heat for at least 30 minutes.^20,36
• Tell your landlord right away if you rent.³⁷
• Get help. The CDC recommends a pest control professional experienced with bed bugs.² See our step-by-step guide on how to get rid of bed bugs.