Bed bug monitors and traps: what they tell you and what they do not
In short
A bed bug monitor is a trap that catches bugs on their way to or from a bed, most often a plastic cup that sits under each bed leg. Monitors are good at showing whether bed bugs are still active after treatment, and at early warning in lets and short lets. They do not clear an infestation, and an empty trap does not prove a room is clear.
Contents
Bed bugs are good at hiding and many people do not react to their bites, so knowing whether they are still there is often harder than it sounds. Monitors give you a way to check without stripping the bed every night.
The main types
Interceptor traps
The most common and most useful kind. Each is a shallow plastic dish with an inner and outer well. You stand a bed leg in the middle. Bugs climbing up to the bed fall into the outer well; bugs climbing down fall into the inner well. The walls are smooth, so they cannot climb out.
Sticky and harbourage traps
Flat cards or small shelters placed along the headboard or skirting, where bugs hide and get stuck or can be seen. Useful in places where a bed has no legs, such as a divan.
Lure monitors
Traps that give off carbon dioxide, heat or a chemical lure to attract bugs from further away. They are used mostly by professionals in hotels and empty rooms.
Where monitors earn their place
After treatment
This is the main use. A trap under each bed leg, checked every few days for four to six weeks after the last visit, shows whether anything survived. If bugs turn up, tell the firm straight away while the follow-up period is still running.
In lets and short lets
Landlords and short-let hosts sometimes leave interceptors under beds between occupants. A bug in a trap at a changeover is far cheaper to deal with than a guest complaint.
When the bites are a mystery
If you have bites but no bugs have been found, monitors for a couple of weeks can help show whether bed bugs are involved before you pay for treatment. A professional inspection is still the quicker way to an answer.
Reading the traps
- Check them every two or three days, with a torch.
- Live bugs, shed skins or eggs in the wells mean activity. Keep a sample in a sealed bag for the specialist.
- Note which leg of which bed; it helps map where the bugs are.
- Wipe and re-seat the traps after each check.
Why an empty trap is not proof
Monitors only catch bugs that walk past them. A bed pushed against a wall, bedding touching the floor, or bugs living in the headboard can all bypass the traps. So:
- pull the bed a few centimetres from the wall;
- tuck sheets and duvets so nothing touches the floor;
- keep storage out from under the bed.
Even then, a few weeks of empty traps is good news, not a guarantee.
What monitors cannot do
They do not get rid of an infestation. Catching a few bugs makes no difference to the population hidden in the frame, the skirting and the walls. For bed bug treatment in Edinburgh, a spray course or heat is still needed, with monitors used to check the result.