Does Having Lots of Spiders Mean You Have Another Insect Problem?

Spiders as a Reading, Not a Problem

A spider population is limited almost entirely by food supply. Web-building species stay where webs catch things and abandon places where they do not, so a wall covered in occupied webs is telling you that a lot of insects pass that spot.

Which means the useful question when someone has an unusual number of spiders is not what to spray, but what they are eating.

What They Are Usually Eating

Flies, midges, moths, gnats, lacewings and mosquitoes — mostly things drawn in by light at night. In most cases the answer is simply outdoor lighting, and that is not an infestation of anything.

So a heavy spider population around a porch with a dusk-to-dawn light is normal and expected, and the fix is the light rather than the spiders.

When It Does Point at Something Else

A sudden concentration of flies indoors, particularly clusters at a window in one room, can mean a dead animal or bird in a loft, a wall void or under a floor. Spiders will follow that quickly.

Persistent small flies around a kitchen or a bathroom can mean a drain fault or a blocked gully. Damp and standing water — a leaking gutter, a blocked drain, a wet cellar — supports midges and gnats. Any of those is worth finding.

The Ones Worth Investigating

Cluster flies gathering in a loft or a spare room in autumn. Small dark flies appearing at one window and nowhere else. Anything accompanied by a smell. Anything in a room with a known damp problem.

If your spiders are concentrated in a specific room rather than spread across the house, that localisation is the clue. Spiders are not evenly distributed by accident.

What This Means for Treatment

Treating spiders while the prey supply is unchanged buys a few weeks. Dealing with the cause — the lighting, the damp, the dead bird, the drain — changes the population for good.

We would rather tell you that than sell you a treatment that has to be repeated. Where there is a genuine persistent spider problem, it is £180 for the first room and £60 for each additional one, and we will say plainly what the treatment can and cannot achieve.