Is It a Bed Bug or Something That Looks Like One?
By the Clark Pest Entomology Team
Last updated: October 28, 2026
Quick answer: True bugs are insects with a beak for piercing and sucking. The bed bug is the one that worries people most. UC IPM describes an adult as about 1/5 inch long, oval, flat, wingless and rusty red. Several other pests get mistaken for it, so check the clues below first.
Which True Bug Did You Find?
Clark has glossary guides for three true bugs. Tap the one that sounds closest. If none fits, the table below covers the look-alikes that get blamed for bed bugs.
Bed BugFlat, oval and reddish brown, about the size of an apple seed. It hides in mattress seams and bed frames and feeds on blood at night.
Western Boxelder BugGrayish black with red lines and a red abdomen, around 1/2 inch long. It feeds on plants, and large numbers gather on patios and walls in fall and spring.
Western Bloodsucking Conenose BugDark brown to black, 1/2 to 7/8 inch long, with a cone-shaped beak. A night-active bloodsucker found in the southern parts of California.
Size, Shape and Where to Look
Small pests get blamed for bed bug bites. Check size, body shape and the spot where you found it before you buy a spray. Our ticks guide, fleas guide and beetles guide cover three of these look-alikes in more detail.
| Pest | Size and shape | Where you find it | Clue that tells it apart |
|---|
| Bed bug | About 1/5 inch as an adult. Oval, flat, wingless and rusty red, per UC IPM | Mattress seams, bed frame joints, headboards and baseboards near where people sleep | Reddish brown to black fecal spots, light shed skins and blood spots on bedding |
|---|
| Bat bug | Looks very much like a bed bug and is wingless too, says Colorado State University | Near bat roosts in upper areas of a building | Under a hand lens, the hairs behind the head are longer than the width of the eyes. Bat bugs tend to turn up one at a time |
|---|
| Carpet beetle larva | The varied carpet beetle adult is about 1/10 inch. The larva is slightly longer, striped and covered in tufts of hair, per UC IPM | Wool, silk, leather, fur and feathers | Bristly brown cast skins and no webbing. Larvae eat animal products, not blood |
|---|
| Flea | No larger than 1/8 inch, reddish brown and flattened from side to side, per UC IPM | Pets and pet bedding. Larvae develop where adults leave dried blood and feces | It jumps. Fleas jump onto socks when you walk through an infested area |
|---|
| Tick | Blacklegged and lone star tick larvae are about the size of a grain and nymphs about the size of a poppy seed, says Cornell | On people and pets | Ticks are arachnids, related to mites and spiders. Nymphs and adults have eight legs |
|---|
| Booklice | About 1/25 to 1/13 inch. They may or may not have wings, per Utah State Extension | Damp books, leaking pipes, cardboard and other spots where mold grows | They feed on mold, so finding them points to a moisture problem |
|---|
What Makes a Bug a True Bug?
Not every insect people call a bug is one. The University of Kentucky says only insects in the order Hemiptera are true bugs. They feed through a beak that works like a straw. Some draw plant sap, some feed on other insects and a few feed on mammal blood. Bed bugs are on the Kentucky list of members.
Are beetles true bugs?
No. Kentucky limits the group to Hemiptera and points out that beetles carry fully hardened wing covers. True bugs have wing covers that are hard only on the half nearest the body. Carpet beetles are beetles, so they sit outside this group.
Young true bugs look like small adults
Kentucky also notes that true bugs grow through egg, nymph and adult stages. A nymph looks like a small adult without wings. That is why a tiny pale bug in a mattress seam can still be a bed bug.
Found Something Small and Red-Brown in the Bedroom?
Look for the bug and its signs
The CDC lists shed skins, bugs in the folds of mattresses and sheets, rusty blood spots on bedding and a sweet, musty odor as signs of an infestation. UC IPM adds dark fecal spots that can be reddish brown, dark brown or black. Check seams, the box spring, the frame and the headboard with a flashlight.
Bites alone do not settle it
UC IPM says telling bed bug bites from mosquito, flea or spider bites is difficult to impossible. The CDC says marks can take up to 14 days to show, and some people have no reaction at all. A bite mark is a reason to look. It is not proof.
Save one
If you catch a bug, put it in a sealed jar or tape it to an index card. A real specimen lets a technician name it in seconds and saves you from treating the wrong pest.
Bed Bugs After Travel or a Secondhand Buy
UC IPM says to inspect luggage before leaving a trip and to wash and dry clothes on the hottest safe setting when you get home. It also says to inspect used furniture, especially beds and mattresses, before you bring it inside.
If you confirm an infestation, UC IPM advises against over-the-counter total-release foggers and says insecticides alone do not control bed bugs. Its guidance is that confirmed infestations should be handled by trained professionals. Clark's bed bug page says the same about how hard they are to remove, and notes they hide well.
Do not leave an infested mattress or couch on the curb with no warning. UC IPM says to take it to the dump or mark it clearly as infested so nobody else brings it home.
Clark's Expert Insight
Name the bug before you buy anything. A flea needs the pet treated. A carpet beetle larva needs the stored wool and fur cleaned out. Booklice need less moisture. Only a bed bug needs a bed bug plan, so a sealed specimen is the best first step.
Bed Bug and True Bug Questions
Are bed bugs true bugs?
Yes. True bugs are the insects in the order Hemiptera, and the University of Kentucky lists bed bugs as members. They share the piercing, sucking beak.
How big is a bed bug and is it round or oval?
UC IPM describes an adult as about 1/5 inch long, oval, flat and wingless. Color runs from rusty red to mahogany. Nymphs are smaller, from 1/20 to 1/5 inch, and lighter yellowish white. Clark's page compares an adult to an apple seed.
How do I tell a bat bug from a bed bug?
You need magnification. Colorado State University says bat bugs have fringe hairs behind the head that are longer than the width of the eyes. Bed bug hairs are shorter. Bat bugs also tend to be found near bat roosts in upper parts of a building.
Is it a bed bug bite or a flea bite?
The marks can look alike. The CDC says bed bug bites resemble mosquito or flea bites. Look at the bug instead. A flea is no larger than 1/8 inch and jumps. UC IPM says it can hop onto your socks as you walk through an infested area. A bed bug is larger, flat and wingless.
Do bed bugs spread disease?
The CDC says bed bugs are not known to spread diseases to people. Their bites can cause itching and lost sleep, and an allergic reaction is possible. Scratching can lead to skin infection, according to UC IPM.
When should I call a professional?
Call once you confirm bed bugs or when you cannot tell what the bug is. UC IPM says confirmed infestations should be handled by trained professionals, who have products and equipment that homeowners do not.