What Do Bed Bugs Look Like? Visual Identification Guide | Mattress Miracle

15 min read | Updated October 9, 2026

A bed bug, Cimex lectularius, is a small, wingless insect that feeds on the blood of people and animals while they sleep. Health Canada describes the adult as having an oval, broad, flat body and a short, broad head. Mattress Miracle, a family-owned mattress store in Brantford since 1997, sells the zippered bed bug encasements for mattresses and box springs that Health Canada suggests once bed bugs are confirmed. Every size below comes from a named authority.

Bed bug size figures disagree because they measure different bugs. An unfed adult is flat and sits toward the small end of the 4 to 7 mm range. A fed adult stretches with blood and grows longer, which likely explains Health Canada's upper figure of 10 mm. Cornell University's quarter inch, about 6 mm, describes an average adult.

Add eggs to that list, and new bites that keep appearing; our checklist of early signs of bed bugs covers both. Either one after a clean-looking check means look again or book a professional inspection. A confirmed find means calling a licensed pest control company, then sealing the mattress in a zippered bed bug encasement so the bed can't re-seed the room.

How Big Are Bed Bugs? Adult Bed Bug Size in mm and Inches

Adult bed bugs are 4 to 7 mm long, about the size of a flattened apple seed, according to the Quebec government's identification page. Cornell University's Integrated Pest Management program puts the average adult at about 1/4 inch (6 mm). Health Canada gives the largest figure: adults can be as long as 10 mm.

Read the table by what each source measured.

For a ruler you already carry, use a dime. The Royal Canadian Mint lists the 10-cent coin at 18.03 mm across and 1.22 mm thick. A 6 mm adult laid on a dime covers about a third of its width, and a 1 mm egg is a little shorter than the coin is thick. Once you know the size, our complete guide to bed bugs in Canada covers bites, treatment and prevention in one place.

What Do Adult Bed Bugs Look Like Up Close?

An adult bed bug is oval, wingless and flattened from top to bottom, which is how it fits into a crack the thickness of a credit card, per Cornell. Purdue University's entomology extension describes the adult as reddish-brown with long, slender legs and antennae. Like every insect it has six legs. It can't fly and can't jump, the Quebec government notes.

• Unfed: flat as a lentil, brown to rust-coloured.
• Fed: longer, swollen and football-shaped, red to dark brown. Cornell adds that once a meal is digested, a black spot shows in the belly.
• Moving: faster than most people expect. The University of Tennessee Extension reports one bug timed at 16 cm in 4.2 seconds, a little over 2 metres a minute.

A fed adult and a hungry one can look like two different insects. Our guide to what bed bugs look like on a mattress shows where adults gather along the piping and tag.

Bed Bug Size at Every Life Stage: Eggs, Nymphs and Adults

Bed bugs grow from a 1 mm egg through five nymph stages to a 4 to 7 mm adult. Each nymph stage needs a blood meal before it can moult into the next, and Purdue says the five stages take about a month in suitable conditions. Health Canada says a female lays at least 200 eggs in her lifetime, about two to four a day.

We couldn't find a Canadian or university source that publishes a size for each middle stage, so the table gives the range instead of inventing one. Eggs hatch in 6 to 17 days, according to Health Canada; Quebec's page says about 10 to 14. Eggs are the stage people miss, and the Mattress Miracle guide to finding bed bug eggs on a mattress shows where females glue them.

Images of Bed Bugs: Where to See Real Photos

Real photographs of bed bugs beat drawings for identification, and two university extension pages publish clear, captioned ones. The Cornell IPM bed bug identification page shows a first-stage nymph between a poppy seed and a sesame seed, an engorged adult and a nymph after feeding. The University of Tennessee bed bug photo page lines up an egg, every nymph stage fed and unfed, and adult males and females against a millimetre ruler. It also shows eggs stuck in a screw hole.

When you photograph your own find, put a ruler or a dime beside it, because size is the first thing a pest professional will ask about.

Insects That Look Like Bed Bugs

Several common household insects look like bed bugs at a glance. The closest relative is the bat bug. Cornell tells the two apart by the fringe of hairs behind the head: longer than the eye is wide on a bat bug, shorter on a bed bug. Most of the others differ in shape, legs or where they turn up.

Flea eggs on bedding are their own problem, and our guide to identifying flea eggs on bed sheets shows how they differ from bed bug eggs.

Where to Look for Bed Bugs on a Mattress and Bed

Bed bugs hide close to where people sleep. The Quebec government says that early in an infestation they stay near where they feed, under the mattress and the box spring. They spread through the room as numbers grow. Health Canada's bed bug fact page adds spots under wallpaper, behind picture frames, inside electrical outlets, and in mattress pads and night tables. Bring a flashlight and something thin like a credit card to open seams.

• Mattress seams and tags: the most common spot. Check the piping along every edge and the sewn-on tag.
• Box springs: remove the dust cover if you can, then check the wooden frame, corners and staple lines.
• Bed frames: every crack, joint and screw hole, plus hollow tubes on metal frames.
• Headboards: tufting, seams and the gap where the headboard meets the wall.
• Nearby furniture: nightstands, dressers and chairs close to the bed.

A box spring with torn fabric is hard to inspect and hard to encase. If yours needs replacing, Mattress Miracle's box springs start at $129.99 for a twin. For a room-by-room routine, our step-by-step bed bug inspection guide covers the order to work in.

Signs of Bed Bugs: Droppings, Blood Spots, Shed Skins and Eggs

Signs of bed bugs are easier to find than the bugs themselves. Cornell calls black fecal spots on the mattress and bed frame the best place to begin an inspection.

• Fecal spots: small black dots, about the size of a pen tip. Wipe one with a wet tissue; Cornell says a rusty colour suggests bed bug droppings, and the University of Tennessee notes they run red when moistened.
• Blood stains: tiny rust-coloured spots on sheets, often from a feeding bug crushed when you rolled over.
• Shed skins: pale, empty shells left after a moult; several in one spot point to bugs growing there.
• Eggs and eggshells: white ovals about 1 mm long, often in clusters glued to fabric or wood.

All of these signs show up fastest against a clean, pale surface, which is one practical reason to keep a washable waterproof mattress protector on the bed between inspections. Mattress Miracle's start at $32 for a twin. A fitted protector leaves the underside open, so it shows the signs but doesn't seal bugs in or out.

What Do Bed Bug Bites Look Like, and When Should You See a Doctor?

Bed bug bites are usually itchy red welts on skin left uncovered during sleep, and they can't confirm bed bugs on their own. Health Canada says a bite can take as long as 14 days to appear, and bites often turn up on the face, neck, arms, legs and chest. HealthLink BC notes bed bugs tend to leave bites in straight rows. Some people don't react at all, and the Mattress Miracle guide to what bed bug bites look like compares them with mosquito and flea bites.

Bed Bug Identification in Quebec

Bed bugs are "punaises de lit" in Quebec French. Adult identification is the same in any language. The Quebec government's bed bug identification page describes adults as visible to the naked eye, oval, 4 to 7 mm long and usually brown. Full of blood, they turn red to dark brown. Its eggs are whitish, pinhead-sized and laid in clusters in small, tight spaces. The same page notes bed bugs turn up even in the cleanest homes and hotels, so finding one says nothing about your housekeeping.

What to Do When You Find Something Suspicious

If you find an insect you think might be a bed bug, capture it. Stick it to white paper with clear tape, which keeps it whole for identification and stops it escaping.

When in doubt, call a licensed pest control professional. Health Canada says bed bugs are very hard to get rid of and strongly recommends a licensed pest control operator. Act early, because a female lays two to four eggs a day.

Health Canada's advice on keeping bed bugs from coming back is to enclose the mattress and the box spring in zippered encasements. Tape over the zipper and keep them on for a full year. As long as the encasement has no rips or holes, bed bugs inside can't bite you and eventually die. Mattress Miracle carries two encasements that zip shut on all six sides. The Health Guard Barrier Guard encasement runs $49 for a twin to $80 for a king. Its listing says one cover fits a mattress or a box spring up to 16 inches deep. The softer Tencel bed bug mattress encasement runs $135 to $178.

Our comparison of mattress protectors and encasements explains why only a full zippered cover belongs in a bed bug plan. After treatment, an everyday mattress protector on top is quick to strip off and check.

Many mattresses can stay once they're encased, which is the point of Health Canada's one-year advice. If yours is torn, finish the treatment first and encase the new mattress before it goes on the frame. One option our advisors often suggest is the Canadian-made Restonic ComfortCare Dalton and Albany, $1,619 in queen.