Do homes with basements face higher pest risk in winter?

It's tempting to treat "having a basement" as the risk factor, but that framing leads to the wrong fix. Nobody is going to fill in their basement. The actual driver is what basements tend to have — sustained moisture, low light, and utility penetrations near ground level — and every one of those is independently fixable without touching the basement's existence at all.

This distinction matters because it changes what "fixing it" looks like. A dry, well-sealed basement carries much less of this risk than a damp one, even though both are still, definitionally, basements.

Sowbugs, pillbugs, and camel crickets aren't opportunists that show up anywhere convenient — their biology ties them to moisture in a fairly literal way. Sowbugs and pillbugs need consistently high humidity because they lack the ability to close off their respiratory system the way many insects can, so a basement that stays damp is one of the few indoor environments that can actually sustain them.

That's also why their presence is diagnostically useful: a lot of camel crickets in a basement is a signal worth acting on, not just a nuisance to spray away. It's telling you the space is damp enough to need attention.

Set moisture aside for a moment, and basements still carry an independent, geometry-based risk: they sit at or below grade, which is exactly where a mouse is already traveling along a foundation looking for a gap. Sill-plate seams and pipe penetrations at that level are shorter, more direct routes indoors than anything on an upper floor.

That's why the fix for the rodent half of this risk factor is straightforwardly about sealing — hardware cloth and steel wool at every visible penetration, backed with sealant, checked and maintained each fall before the ground freezes.