Two routes through one trap
A typical interceptor is a small dish that sits under a bed or chair leg. It has an inner well and an outer well. Bugs that climb up from the floor tend to fall into the outer well, while bugs that climb down from the furniture tend to fall into the inner one.
This means a catch can show both activity and direction. However, it only works while the leg is the bugs’ route. If the bed touches a wall or the bedding trails on the floor, bugs can bypass the trap completely.
Measure before you buy
Interceptors only work when they fit your furniture. Measure the widest point of each foot, and check the floor area around it. You can measure each bed leg before you buy interceptors because a set that is too small will not work.
Some furniture, however, will not fit at all. Large casters, broad divan feet and floor-mounted frames are common problems. In that case, a different tool may suit you better, such as the sticky traps compared in our guide.
Set up the bed
First, move the frame a short way from the wall. Next, keep duvets, sheets and charging cables off the floor, because any bridge gives bugs a way round the trap. Then place every leg centrally in its dish.
Do not add powders, oils or talc unless the manufacturer tells you to. These residues can change the surface and make it less reliable. Also check that the trap is stable, because a wobbling bed is hard to sleep on.
If you want the full routine, our step-by-step guide to using bed bug traps covers placement in more detail, since a small gap in the setup can let bugs bypass the trap.
Inspect and record
Check the dishes on a regular schedule, in good light, because small bugs are easy to miss. Weekly works for many people, but pick a day you will keep to. Look in both wells and use a torch if the dish is dark.
If you find a specimen, photograph it and keep it. A clear photo helps you or a professional identify it, and the guide to telling bed bugs from look-alikes can help you compare. Then clean the dish as the product instructions say, and note the date and which well held the catch.
Interceptors after treatment
Interceptors are also useful once a treatment is finished, because they give you a simple way to watch for any sign of activity. Our guide on monitoring after bed bug treatment explains how long and how often to check. Keep them in place until your professional says otherwise.
They are useful with second-hand items too. Fit them to a bed you have just moved into a room, although you should still check second-hand furniture for bed bugs before it comes indoors.
What an empty trap does not prove
An interceptor is a monitor, not a cure. It catches some bugs, but it will not clear an infestation by itself. As a result, you should never treat it as a treatment.
Equally, an empty trap is not proof that your home is clear. Bugs may be using another route, or the trap may be fitted badly. Read our guide on what traps can and cannot do for the full picture, and speak to a pest control professional if you keep seeing signs of bites or bugs.
Sources and disclosure
General monitoring claims are checked against peer-reviewed research. Product identity and pack format come from the current listing. Amazon links include dummy tag bedbugtraps-21; the site does not claim an active earning relationship.