Bugs That Look Like Bed Bugs (and Bugs in Bed That Are Not)

A small brown bug on a pillow is often something else, and the difference matters: EPA points out that there are many bugs that look like bed bugs, so an accurate identification is a critical first step to avoid costly treatment for the wrong bug. This guide covers the lookalikes. For every bed bug life stage and what an infestation looks like, see our bed bug identification guide.

Bed bug lookalikes at a glance

The test that settles most cases

Bed bugs are true bugs, and EPA’s description is the cleanest checklist there is. Adults are about the size of an apple seed, 5 to 7 mm long, brown and flat with an oval body if they have not fed recently, and balloon-like, reddish brown and more elongated after feeding. They have short golden hairs, a three-segmented beak and wings that are not used for flying. Young bed bugs are smaller and translucent or whitish yellow, and can be nearly invisible to the naked eye until they feed.

The evidence they leave is often more useful than the bug. EPA lists rusty or reddish stains from crushed bed bugs, dark spots about the size of a full stop that are excrement and may bleed into fabric like a marker, eggs and eggshells about 1 mm long and pale yellow, shed skins, and live bugs. Kentucky entomologists add a caution here: cockroach droppings are pepper-like specks similar in appearance to bed bug spotting, but can usually be told apart by location, because cockroaches seldom congregate on beds the way bed bugs do.

So ask four questions: is it flat, wingless, apple-seed sized and reddish brown (or a paler, smaller nymph), and are there dark ink-like spots on the seams? Four yeses mean a probable bed bug worth confirming.

Bat bugs and swallow bugs: the lookalike that needs a microscope

Bat bugs and swallow bugs belong to the same family as bed bugs, and Kentucky’s bed bug fact sheet says the species that normally feed on bats and birds can be told apart from those that prefer humans, but that entomologists and pest professionals are the people to make that call. They bite people too, especially once the bats or birds are no longer present.

Colorado State University’s identification key gives the feature that separates them. Look at the fringe of hairs around the eye and along the edge of the shield behind the head. On a bed bug those hairs are shorter than the width of the eye. On the bat bugs Cimex pilosellus and Cimex adjunctus they are longer than the width of the eye, and the long, dense hairs along the sides and back give a bristly look. The swallow bug, Oeciacus vicarius, has hairs shorter than the eye’s width, but they grow densely and lie flat all over the body. These are features you need a good lens or a microscope to judge, which is why a sample is worth more than a photograph.

Timing is a clue. The same key lists bat bugs and swallow bugs as turning up in living areas in early autumn and in mid-spring, when migrating bats and swallows leave and return to the building, while bed bugs are found year round.

That changes the treatment entirely. Kentucky advises that if bat bugs or bird bugs are present, roosting and nesting sites should be the focus, combined with excluding the wild hosts. Treating the mattress alone leaves the source untouched. Birds bring a second problem that is often confused with both: see our guide to bird mites, which bite after a nest is abandoned. For the exclusion side, our guides to bat removal costs and bird control costs cover what the work involves.

Carpet beetles: a frequent false alarm in bedding

Carpet beetles are a frequent source of bed bug scares, and EPA’s own bed bug pages point readers to a New York City health department sheet devoted to telling a bed bug, a cockroach and a carpet beetle apart.

Adults

Kentucky describes adult carpet beetles as small, 1/16 to 1/8 inch, oval and either black or mottled white, brown, yellow and orange. Penn State gives the common Anthrenus species as 2 to 3.5 mm, with the varied carpet beetle at about 3 mm. They feed on flower pollen and, in Kentucky’s words, often appear on windowsills in springtime. UC IPM notes they are often carried in on cut flowers and can fly in through open windows. A rounded, speckled beetle with hard wing covers on a windowsill or a duvet is not a bed bug.

Larvae, and the “bites” that are not bites

The larvae are where the trouble starts. Kentucky describes them as about 1/8 to 1/4 inch long, tan to brownish, slow moving and densely covered in hairs or bristles, and they feed on wool, feathers, fur and pet hair, including down pillows, comforters and blankets. Penn State reports that dermatologists have documented reactions to carpet beetle larval hairs since 1948, which some patients describe as being bitten by something, with intense itching and a rash. Penn State adds that this sensitisation appears to follow long-term exposure.

So itchy marks plus small brown larvae in the bed can happen with no bed bugs at all. The cure is removing the larval food source. Our guide to carpet beetle treatment costs explains what is worth paying for.

Our data: carpet beetles peak in spring, bed bug records in winter

The Pest Control Brief analysed iNaturalist research-grade records across the US to see when people photograph and identify each of these animals. The index below adjusts for how many people are out recording in a given month: 100 is a taxon’s usual share of all records, and 200 means twice its usual share.

Carpet and hide beetles reach an index of 317 in March and 200 in April, more than three times their usual share, then fall to 23 by September. That matches Kentucky’s note about adults on spring windowsills, and it means a small speckled beetle found in March is far more likely to be a carpet beetle than anything else on this list. Ticks peak at 227 in May. Bed bug records run the other way, highest from October to January (174 in December), but read that carefully: bed bugs live indoors all year, so a winter rise mostly reflects people noticing and photographing them when little else is about, and the bed bug figures rest on only 867 records. These are records of sightings, not of infestation rates.

Little brown bugs in bed that are not bed bugs

Several small brown beetles and nymphs wander onto beds from elsewhere in the house. None of them feeds on blood.

• Spider beetles have a globular body and long legs that make them look like tiny spiders. The University of Florida gives adults as 1 to 5 mm and notes some species can fly. A University of Nebraska manual links them to old, damp stored food and to accumulations of rodent, bird or bat droppings in walls and attics, from which they can emerge into rooms.
• Cigarette and drugstore beetles are about 1/8 inch, cylindrical and uniformly light brown, according to UC IPM. In the home they are most often found in pet foods, cereals, nuts and spices, and adults stray from there. Our pantry pests guide covers finding the source.
• Booklice are pale, about 1 mm and wingless, and Clemson states they do not bite people or pets. They point to damp, not to bed bugs.
• Cockroach nymphs are wingless and, for the German cockroach, dark brown to black with two dark parallel bands running down the shield behind the head, according to UF/IFAS.

Our guide to little brown bugs in the house covers these and the rest of the brown-bug list in more detail.

Biters that are not bed bugs: fleas and ticks

If something in the bed is biting and it is not a bed bug, fleas and ticks are the usual answer. UC IPM describes adult fleas as no larger than 1/8 inch, reddish brown and wingless, flattened from side to side so they look as if they are walking on edge. The jump is the giveaway: a bed bug cannot jump. Kentucky notes that animal hosts need to be present for extended periods for fleas to become established, and suggests walking the house in white socks pulled high to spot them. Our guide to the flea life cycle explains why they reappear after treatment.

Ticks have eight legs as nymphs and adults, where bed bugs have six. UC IPM gives the blacklegged tick nymph as about the size of a poppy seed, 1/25 inch, and the unfed adult female as about 1/8 inch, swelling to 3/8 inch or more when fed. A tick found in bed has almost always been carried in on a person or pet. See our tick identification guide for the species and what to do if one is attached.

How to get a definite identification

1. Collect the bug intact. Kentucky entomologists recommend a non-crushable container, such as a pill bottle or small jar, rather than an envelope or tape, which flattens the features an entomologist needs to see. Seal it and label where and when you found it.
2. Take it to someone who can look under magnification. EPA notes that your state cooperative extension office may be able to help with identification, and a licensed pest professional can do the same.
3. Do not treat on a guess. Kentucky warns that bleach, alcohol, cigarette lighters and foggers should not be used against bed bugs. Confirmed bed bugs are usually a job for a licensed professional; our bed bug treatment cost guide shows why getting the identification right first saves money.

If you have marks on your skin but no bug, bites alone will not tell you the culprit. Our bite identification guide explains why, and when to see a doctor.

Frequently asked questions

What bugs look like bed bugs but are not?

The usual lookalikes are carpet beetles and their larvae, bat bugs and swallow bugs, spider beetles, cigarette and drugstore beetles, booklice, cockroach nymphs, fleas and ticks. Beetles have hard wing covers, fleas jump, and ticks have eight legs. A bed bug is flat, wingless, reddish brown and 5 to 7 mm long as an adult, and leaves dark ink-like spots on mattress seams.

How do you tell a bat bug from a bed bug?

Under magnification, look at the hairs around the eye and along the edge of the shield behind the head. Colorado State’s key says they are shorter than the width of the eye on a bed bug and longer on bat bugs, which look more bristly overall. It takes a lens or microscope, so collect a specimen in a crush-proof container and have an entomologist or pest professional confirm it.

Is it a carpet beetle or a bed bug?

Adult carpet beetles are round and speckled or black, about 1/16 to 1/8 inch, with hard wing covers, and they often appear on windowsills in spring. Bed bugs are flat, oval, wingless and reddish brown. Carpet beetle larvae are hairy, tan to brown and slow, up to about 1/4 inch long. They do not suck blood, though their hairs can cause an itchy rash in sensitised people.

What are the little brown bugs in my bed if not bed bugs?

Common answers are carpet beetle larvae, spider beetles, cigarette or drugstore beetles that strayed from the pantry, and cockroach nymphs. None of these feeds on blood. If something is biting, check for fleas, which jump, and ticks, which have eight legs. Collect one intact in a small container so it can be identified properly before you pay for any treatment.

Sources

• US Environmental Protection Agency, Bed Bugs Appearance and Life Cycle; How to Find Bed Bugs.
• Colorado State University Extension, Key Physical Features Used to Separate a Bed Bug from Related Insects (Bat Bugs, Swallow Bugs), revised April 2020.
• University of Kentucky Entomology, ENTFACT: Bed Bugs; Carpet Beetles; Cockroach Elimination in Homes and Apartments; Mystery Bites: Insect and Non-Insect Causes.
• Penn State Extension, Carpet Beetle Dermatitis, 2017.
• UC Statewide IPM Program, Pest Notes: Carpet Beetles; Pantry Pests; Fleas; Lyme Disease in California.
• University of Florida, UF/IFAS Stored Product Pests collection: spider beetle; EDIS IN128, German Cockroach.
• University of Nebraska-Lincoln Extension, IPM for Fabric and Pantry Pests manual, 2012.
• Clemson Cooperative Extension, HGIC 2403: Booklice, 2004.
• The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.