What winter pests eat stored food in garages or basements?

It's easy to lump 'pests eating stored food' into one category, but rodents and stored-product insects are functionally different problems that happen to share a location. A rodent is an opportunistic forager: it doesn't need the food to already be damaged, it creates the damage by chewing its way in, and it does this regardless of season or ambient temperature because it needs to eat and it needs shelter, and a garage full of dry goods offers both.

Stored-product insects are a different mechanism entirely. Extension guidance consistently notes that species like the Indianmeal moth and sawtoothed grain beetle 'live, eat, and grow inside stored products,' and a meaningful share of infestations start before the product is even carried into the house — the eggs or larvae were already present in the package at purchase (University of Minnesota Extension; NC State Extension). Cold slows their development but a warm basement resets the clock.

The busted assumption behind this whole question is that an unheated space is inherently pest-safe for stored food. For insects, that's a half-truth — activity does slow, but dormant eggs and larvae aren't killed by garage-cold the way a hard freezer would kill them, and once that same bag of birdseed comes inside to a heated basement, development resumes. For rodents, the assumption doesn't hold at all: cold weather is precisely what drives rodents toward indoor food sources in the first place, which is the same seasonal mechanism behind winter being documented peak season for indoor rodent activity generally.

The same container upgrade solves both categories. Glass and metal containers with tight lids exclude a gnawing rodent completely and make it much harder for stored-product insects to infest a fresh package from the outside — though it won't undo an infestation that arrived already inside the bag. That's why buying smaller quantities more often, checking new purchases before they go into long-term storage, and freezing a suspect item before it joins the rest of the pantry are the practical extension-backed habits worth adopting alongside the container swap.