What do bed bugs look like, and what they're not

The six things to look for

1. Live adults. 5-7 mm long (about the size of an apple seed). Flat oval shape, reddish-brown, six legs, short antennae. A fed bug is rounder and darker red; a starved bug is flat and brown.
2. Nymphs (immature stages). Five molt stages, from 1.5 mm (just hatched) up to nearly adult size. Nymphs are translucent to pale yellow until they feed, then visibly red with blood inside.
3. Eggs. White, about 1 mm long (rice-grain shape), in clusters of 5-10 in protected crevices. Hard to see without a flashlight.
4. Fecal spots. Dark brown to black, pinhead size, often in clusters or smears along mattress seams, behind headboards, in corners of frame joints. Smudges if wiped with a damp cloth (digested blood).
5. Shed casings. Translucent amber-brown nymph skins, intact and shaped like the bug. Each nymph sheds five times before reaching adult; populations leave hundreds.
6. Bite pattern. Suggestive but not diagnostic. about 50% of people don't react visibly. See the dedicated bed bug bites article.

Lookalikes: what people often misidentify as bed bugs

• Carpet beetle larvae. Brown, fuzzy, caterpillar-like, about 4-5 mm. Found in carpets, closets, wool fabric. Don't bite humans but cause similar fabric damage suspicion.
• Cockroach nymphs (baby roaches). Smaller and longer than bed bugs, six legs that are visibly more prominent, and they move fast, bed bugs are slow.
• Fleas. Smaller (1-3 mm), darker, jump rather than walk. Concentrate around pets and floor level rather than beds.
• Bat bugs. Almost identical to bed bugs to the naked eye; distinguished by longer hair on the pronotum (the area behind the head). Found in homes with attic bat colonies. Treatment is similar but you need to seal off the bat entry too.
• Booklice (psocids). 1-2 mm, pale, found in humid areas around books and paper. Harmless, no bites.
• Spider beetles. Round, glossy, about 2-4 mm. Stored-product pests, not blood feeders.
• Scabies mites. Microscopic, but the resulting skin reaction can look similar to bed bug bite clusters. Itching is intense and concentrated between fingers, wrists, elbows, atypical for bed bugs.

Where to look first

Bed bugs aggregate within 1.5 meters (5 feet) of where the warm-blooded host sleeps, they evolved as nest parasites. EPAand Penn State Extension both rank these spots in order:

• Mattress seams (head end and foot end), tag, piping, and under any zippered encasement.
• Box spring fabric, especially staples and joints; check underside if you can flip it.
• Bed frame corner joints and screw holes. Look behind the headboard if it mounts to the wall.
• Padded headboard seams and back fabric, this is the underrated hotel hotspot.
• Nightstand drawers, especially seams and corners.
• Outlets and switch plates within a meter of the bed (turn off power first if you remove plates).
• Wall-to-floor edges, baseboards, and any small crack within the 1.5 m radius.