The short answer
Bed bugs on a mattress gather along the seams, piping, labels and the corners where the fabric folds, and leave dark spots of droppings, pale shed skins and tiny eggs. A mattress can usually be kept: it is treated with the rest of the room and then sealed in a zipped encasement, which traps any survivors and makes new signs easy to spot.
The mattress is where most people first find bed bugs, and it is the thing they most want to throw away. Both reactions make sense, but the second is usually a mistake. Here is how to read what you find on a mattress, and what a specialist will normally do with it.
Where on the mattress to look
Bed bugs do not live on the open surface where you lie. They hide in tight, dark places close by and come out to feed at night. On a mattress that means:
- The seams and piping round the top and bottom edges, especially at the corners.
- Labels and tags, where the fabric doubles over.
- Handles and air vents on the sides.
- Buttons or tufts on the sleeping surface of older mattresses.
- The underside, where it meets the base.
Strip the bed, take a bright torch, and run a plastic card slowly along the seams. Check the divan base or bed frame too: the stapled fabric under a divan and the joints of a wooden frame are just as popular.
What the marks mean
| What you see | What it usually is | How sure |
|---|---|---|
| Live oval, flat, reddish-brown insects about 5 mm long | Adult bed bugs | Certain |
| Clusters of tiny black or dark brown dots that smear when wiped with a damp cloth | Droppings (digested blood) | Strong |
| Pale, empty, bug-shaped husks | Skins shed by young bed bugs as they grow | Strong |
| Very small white oval specks, about 1 mm, stuck in seams | Eggs | Strong if found with other signs |
| Small rusty or red smears on the sheet | A bug crushed after feeding, or a scratched bite | Suggestive only |
| Bites with nothing else found | Could be bed bugs, or something else | Weak on its own |
The NHS lists bites, spots of blood on bedding, dark droppings on the mattress and the bugs themselves as the signs to look for. If you find something but are not sure, put it in a sealed bag or jar so a specialist can see it.
Should you throw the mattress away?
Usually not. A mattress can be treated along with the rest of the room, by heat, by steam on the seams, or as part of a spray course. Replacing it has three problems:
- It spreads them. Carrying an infested mattress down the stairs and out of the door shakes bugs and eggs onto carpets and landings.
- The new one gets them too. If the room and the bed frame are not treated, the bugs simply move into the new mattress.
- It costs more. A new mattress is often dearer than an encasement and the treatment you need anyway.
There are exceptions. A mattress that is torn open, very old or so heavily infested that the specialist advises against keeping it may be better gone. If so, wrap it completely in plastic sheeting before it leaves the room, and label it so nobody takes it home from the street.
How an encasement works
After treatment, many specialists recommend a zipped mattress encasement: a close-fitting cover that surrounds the whole mattress, with a fine zip and a flap over the end so bugs cannot get in or out.
It does two jobs. Any bug or egg that survived inside the mattress is sealed in and cannot reach you to feed. And the smooth, pale outside gives bugs nowhere to hide, so any new sign is easy to spot when you change the sheets.
A few practical points:
- Buy one sold for bed bugs, with a tested zip, not an ordinary waterproof protector.
- Fit it straight after treatment, before the bed is made up.
- Leave it on. Adult bed bugs can survive for months without feeding, so most advice is to keep an encasement on for at least a year.
- Check it for tears when you change the bedding. A small hole lets bugs through.
MyBuilder gives encasements as roughly £20 to £50 each. A divan base can be encased too.
What not to do
- Do not spray the mattress with shop insecticides. Most are not meant for surfaces you sleep on, and the bugs inside the seams are rarely reached.
- Do not move to the sofa or another bedroom. The bugs follow you and you then have two rooms to treat.
- Do not put the mattress outside to “air”. Birmingham weather will not kill bed bugs, and it may spread them to a neighbour’s bins.
When to call someone in
If you have found any of the strong signs in the table, it is time for a specialist. Bed bugs on a mattress almost always mean bugs in the frame, the bedside table and the skirting too, and treating only the mattress leaves those behind. An inspection maps how far they have gone, and a heat treatment deals with the mattress and frame without insecticide on the bed.
You can send a request below for a specialist who covers your Birmingham postcode.