You never see where they come from. There are two of them by the fruit bowl, then there are nine, and swatting is pointless because the ones flying are a fraction of what is actually in the room. That last part is the bit people get wrong.

What you can see are adults, and adults are the short end of the life cycle. The eggs and larvae are in the damp organic matter that the adults found: the soil of a houseplant, the film in a drain, a bag of potatoes at the back of a cupboard, the bin liner's seam. Killing the visible ones does nothing to the next generation, which is why the numbers come back a few days after you think you have won.

A light trap works on the adults but works continuously and without you. Blue and ultraviolet wavelengths attract them reliably, and a sticky surface holds what arrives instead of asking you to be in the room with a cloth. Because it runs all night, it takes out the breeding adults over a period rather than the handful that happen to be flying when you walk in.

The pad is also the only useful measurement you will get. Two days of catch tells you honestly whether this is a small nuisance or an infestation with a source you have not found yet.

Here is the limit, and it is the one that decides whether this works for you. It does not find or treat the breeding site, and if you do not deal with that the trap becomes a permanent appliance rather than a fix. Check plant soil first, then drains, then anything ripening.

It is also indoor and low-level. It is not for a garden, not for mosquitoes outdoors, and it needs to be near where they actually are, not in the corner that is convenient for a socket.

And the refills are ongoing. At around thirty-five dollars for a base and two pads, price the pads before deciding, because that is the real cost of owning it.