Mice in winter: how Saskatchewan homes get invaded

Three nights below -10°C and the phone starts ringing. Every November our Regina office takes a wave of calls from homes that didn't see a mouse all summer and now have droppings in the pantry drawer. Mice don't appear in winter — they move from the perimeter into the warm space they were already living next to. The thermal gradient at a 6mm gap in late November is the loudest signal in the building envelope.

Why winter forces them inside

A mouse can squeeze through a gap the width of a pencil — about 6mm. Every Saskatchewan house has gaps that size: dryer vents that didn't quite seal, foundation cracks, the corners of garage doors that warp in the cold, gas-line entries, and (the classic) the gap behind the kitchen stove where the gas line comes through the wall. In July, the yard has seeds, grasshoppers, and shelter under the deck — your house is irrelevant. In January, the heat plume from a leaky dryer vent is visible to a mouse from 10 metres away. That's the migration we treat against.

Snap traps aren't the answer (alone)

The most common mistake we see in Regina: snap traps in the pantry, nothing on the perimeter. You catch four mice in three nights, the traps go quiet, and you think you're done. The population outside backfills through the same 6mm gap within 7–10 days. The fix is perimeter first, traps second — every time.

A proper winter mouse plan looks like:

1. Walk the perimeter. Document every gap a pencil fits through. Don't miss vents, utility penetrations, weather-strip gaps, or the underside of garage doors.
2. Seal with the right material. Stainless-steel mesh or copper wool packed tight for gaps under 25mm. Steel-reinforced expanding foam for anything larger. Plain hardware-store foam alone is a waste of an afternoon — mice chew through it inside 72 hours, and we've pulled out plugs with tunnel marks to prove it.
3. Bait outside, trap inside. Tamper-resistant bait stations spaced every 9–12 metres along the foundation intercept mice before they cross the envelope. Snap traps (T-Rex or Victor metal-pedal — wood snap traps misfire below 0°C) on the inside catch what's already there.
4. Re-inspect after two weeks. Activity should stop. If it hasn't, there's a gap we missed.

When to call us

If you've got droppings in two or more rooms, or you're hearing scratching in the wall behind the bed at 2 a.m., the population has already established a nesting harborage somewhere — usually in attic insulation, behind a basement utility chase, or under a bathtub. DIY catches the slow ones at the food source and misses the ten others using a different route. A proper inspection finds the entry points and the harborage; the 60-day warranty covers any return inside that window.

If you're not sure whether what you're seeing is mice, voles, or something else, text us a photo of the droppings against a coin for scale — we can usually call it from the picture. For the bigger picture across our service area, see our mice control work in Regina, and pair this with fall wasp prep since the two sealing jobs share a checklist.