5 signs of bed bugs (and where to look first)

Bed bugs rarely announce themselves. An adult is about the size of an apple seed, hides in cracks during the day, and comes out at night to feed for a few minutes before disappearing again. That is why a single clue is rarely enough: if two or three of the signs below show up together, treat it as a strong suspicion and get a professional inspection rather than waiting. It almost always gets worse.

1. Bites in lines or clusters when you wake up

Bed bug bites are the sign most people notice first, and also the easiest to misread. They usually appear on skin exposed during the night — arms, neck, shoulders, face — as small red, itchy bumps. The classic pattern is a line of three or four bites, sometimes called "breakfast, lunch and dinner," or a tight cluster where the bug probed several times before feeding.

Two things make bites unreliable on their own. Reactions vary enormously: some people develop large welts, others barely react, so one person in a couple can be covered in bites while the other has none. And bites look a lot like mosquito bites or hives. Bites alone are a reason to investigate, not a diagnosis — but bites that keep appearing night after night, in the same bed, are a much stronger signal than a one-off itchy morning.

2. Black spots on mattress seams and the headboard

This is the most reliable sign you can find yourself. Bed bugs digest blood and leave behind tiny dark spots — their droppings — that look like specks of black pepper or dots made with a fine-tip marker. You will find them where bugs rest after feeding: along mattress seams and piping, in the folds of the mattress tag, behind the headboard, and in bed frame joints.

Run your finger over a suspicious spot: bed bug droppings smear slightly, like ink, because they are dried blood. Rust-coloured stains on the sheets come from bugs crushed during the night. Black spots plus rust stains around the same bed almost certainly mean an active infestation.

3. Shed skins in seams, cracks and behind furniture

Bed bugs moult five times as they grow from nymph to adult, leaving behind a pale, empty shell each time. These shed skins are translucent, slightly yellowish, and shaped exactly like a bed bug. Because they do not decompose quickly, they accumulate in harbourages: inside mattress seams, behind loose wallpaper, in bed frame screw holes, and along baseboards near the bed.

Shed skins are useful because they tell you the infestation has been there long enough for bugs to grow. Skins of different sizes suggest several generations — weeks of establishment. That is also why a quick spray of the mattress alone never works: the skins show you where the bugs actually live, and those places are cracks and joints, not open surfaces.

4. A sweet, musty smell in the bedroom

Bed bugs release pheromones, and a larger infestation gives off a distinctive sweet, musty odour — often compared to coriander or a damp, mouldy room. Most people will not notice it in a small, early infestation, and a bedroom can smell musty for plenty of other reasons, especially in older Montreal plexes with poor ventilation.

Still, the smell is worth noting when it appears with other signs, or when guests comment on it before you do. If it is strongest near the bed and does not go away after airing the room and washing the bedding, add it to the evidence for your inspection.

5. Live bugs — usually found by accident

Seeing a live bed bug is confirmation, full stop. You are most likely to spot one when you disturb its hiding place: lifting the mattress, pulling the bed away from the wall, or emptying a nightstand drawer. Adults are reddish-brown and apple-seed sized; nymphs are smaller and paler. They do not fly or jump, so anything that hops is a flea, not a bed bug.

Do not be reassured if you only find one: bed bugs hide in groups, and a single visible bug usually means dozens more in cracks you have not checked. Do not throw the mattress out immediately — dragging infested furniture through hallways spreads bugs to other rooms and to your neighbours. Bag what you can, leave the furniture in place, and call a professional.

Where to look first: the 15-minute check

Start with the bed, because that is where bed bugs feed and cluster. Work in this order, with a flashlight and an old credit card to probe seams:

• Mattress seams, piping and tags — peel the seams open gently and check both sides, top and bottom.
• Headboard and bed frame joints — especially screw holes, cracks and anywhere wood meets wood.
• Nightstand and dresser — inside drawers, behind them, and in the joints underneath.
• Baseboards and electrical outlets near the bed — bugs hide behind outlet covers and in the gap where the baseboard meets the wall.
• Curtains, picture frames and books closest to the bed — in a heavier infestation, they spread well beyond the mattress.

Check every bed in the home, not just the one with bites: children often react less, and a guest room can harbour bugs silently for months. If you find nothing but bites continue, keep checking weekly — early infestations are easy to miss on a first pass.

What to do if you find signs

Do not panic, and do not reach for a supermarket bug spray: a partial treatment scatters bugs into wall voids and makes the professional job harder. Wash bedding and clothing on the hottest cycle and dry on high heat, and vacuum seams and cracks thoroughly, emptying the vacuum outside right away. Then book an inspection. Our bed bug treatment starts with a full inspection and a written report, so you know exactly what you are dealing with before any work begins. Inspection: $75 — waived if you proceed with treatment.