How Do I Seal Entry Points to Keep Wasps From Entering My Home?

UNH Cooperative Extension notes that a crack roughly 3/16 of an inch wide is enough to let most wasps through, which is smaller than many homeowners would think to check for. That means a thorough inspection needs to look past the obviously large gaps — a compressed gasket around a pipe, a gap where trim has pulled slightly away from siding, or a small tear in a vent screen are all realistic entry points at that scale.

Never seal an opening that an active nest is currently using as its only exit. If wasps are actively entering and leaving through a gap, sealing it traps them inside rather than keeping them out, and Penn State Extension warns that trapped wasps can chew through interior sheetrock looking for another way out — turning a simple sealing job into wasps ending up inside the living space. The safe windows for this work are late fall or winter, once a colony has died off for the season, or early spring, before new queens are actively scouting for sites. In southern New Hampshire (Manchester, USDA hardiness zone 5b–6a), those windows are concrete: the average first hard freeze arrives around October 19 by National Weather Service climate normals, and it's the sustained cold after that point that ends colonies — so late fall into winter is the safe post-season window, and early spring means finishing before overwintered queens scout in April and May.

Caulk or expanding foam works for cracks and gaps around trim, siding, and utility penetrations; fine mesh screening covers larger openings like vents without blocking their intended airflow function. Go around the full exterior methodically rather than only checking spots where you've previously seen activity, since a 3/16-inch gap is easy to miss without a deliberate check. If you're unsure whether a specific opening currently has activity, that uncertainty is a reason to confirm before sealing, not to seal anyway.