7 Bed Bug Signs Most People Miss
Most calls we get open with "I think I have bites." That is a poor starting point: roughly three people in ten have no reaction at all to bed bug bites, and many skin reactions blamed on bed bugs come from something else. The other six signs on this list are physical, verifiable, and far more reliable. Here is what a technician inspects, in the order they do it.
1. Pen-tip black dots along the mattress seam
This is the first place a technician looks, and by far the most reliable sign. These are digested blood droppings: small black dots, usually clustered, concentrated along seams, under the mattress label, and in box spring grooves. Unlike a dirt stain, they bleed when rubbed with a damp cloth, leaving a rust-coloured halo rather than wiping away.
Their location says a lot. Concentrated on a single seam, they signal a recent, localized infestation. Spread around the whole mattress perimeter, onto the bed frame and into the baseboards, they indicate a population established for months. That difference decides whether one room or the whole dwelling needs treatment.
2. Translucent shed skins in the bed frame grooves
A bed bug passes through five stages before adulthood and leaves a shell behind at each moult. These casings look like empty amber husks, very light, often caught in bed frame screws, under slats, or in the fold of an upholstered headboard. They do not crumble like dead skin: they keep the insect's full shape, legs included.
Their presence proves something droppings alone do not: the population is breeding on site. A bug brought in on a suitcase and long dead leaves no moults. Five shed skins mean at minimum five weeks of development, and therefore that the problem is older than the client almost always believes.
3. A sweet, slightly rancid smell in the bedroom
Bed bugs release alarm pheromones whose odour suggests coriander or slightly turned almond. At low density, nobody notices it. Once a population is established, it becomes perceptible on entering the room, especially in the morning after the bedroom has been closed all night.
It is an imperfect but useful sign: its absence tells you nothing, but its presence indicates an already significant infestation. Occupants habituate and stop perceiving it — visitors usually notice first. If someone has mentioned it to you, do not dismiss it.
4. Small blood spots on the sheets, never in the same place
A blood-fed bug crushed during sleep leaves a rust-brown spot two to four millimetres across. What distinguishes these from a nosebleed or a cut is their scatter: they appear in different places from one night to the next, often near the shoulders, neck, and upper back, where skin stays uncovered.
Washing the sheets erases the evidence. If you suspect something, put on a white sheet for two or three nights and photograph whatever appears, including a reference object — a coin — for scale. That is concrete information a technician can work with.
5. Bites in lines or clusters, worse on waking
Here is the best-known and least conclusive sign. Bed bug bites often form lines of three or four, or clusters, on areas uncovered during sleep. They typically itch more on waking than at the end of the day. But flea bites, an allergic reaction, contact dermatitis, or a reaction to soap all produce similar lesions.
No physician and no technician can confirm bed bugs from bites alone. That is why we never bill a treatment on that basis: the inspection exists precisely to find one of the other six signs before committing to anything.
6. Live bugs somewhere other than the bed
Finding a live bug in the bed confirms the diagnosis. Finding one three metres from the bed — behind a picture frame, in a baseboard groove, under a nightstand lip, in a curtain fold — changes the scale of the job entirely. It means the harbourage near the bed is saturated and the population is expanding.
At that stage, treatment limited to the bedroom is unlikely to be enough. It is also the point where the risk of transfer to a neighbouring unit becomes real in a plex or apartment building, and where the question of coordinating with the landlord has to be raised.
7. A neighbour who was just treated
This sign is not found inside the dwelling: it is found next door. In a duplex, triplex, or apartment building, a treatment at a neighbour's pushes survivors to migrate through plumbing stacks, floor voids, and electrical chases. An infestation appearing two to six weeks after a neighbouring treatment is no coincidence.
If you learn that an adjoining unit has been treated, have yours inspected without waiting for visible signs. At that stage the population is still tiny and treatment is shorter, cheaper, and far less demanding in preparation.
Unsure about one of these seven signs? The inspection is free and without obligation — a ParasiteMontréal technician identifies the species on site and tells you frankly whether treatment is warranted.
