Where Do Spiders Go In The Winter?

The reason generic answers to this question feel unsatisfying is that they treat "spiders" as a single species with a single winter strategy, when the honest answer splits cleanly into two groups with opposite stories. Group one lives indoors permanently and experiences no winter at all — for them, the question doesn't really apply. Group two lives outdoors, and for them winter genuinely is the end of the visible adult population, with survival handled entirely by the next generation in a form most people don't expect.

Common house spiders and cellar spiders are synanthropic — a term entomologists use for species that specifically thrive in human-built environments rather than merely tolerating them. Penn State Extension and UF IFAS both note these spiders live continuously in basements, crawl spaces, garages and similar quiet corners, cycling through generations indoors without any seasonal migration in or out. Peer-reviewed research on the common house spider documents an indoor life cycle of roughly two to three months, with females producing egg sacs continuously — meaning the spider in your basement corner in January could easily be a descendant of one that overwintered there the year before, not a new arrival at all.

The line "spiders lay eggs that survive winter" is repeated everywhere and is subtly wrong. A raw, undeveloped spider egg generally can't survive a hard freeze. What actually happens is more specific: eggs hatch inside the protective silk sac in late summer or early fall, and the spiderlings themselves undergo a physiological cold-hardening process, producing glycerol and related cryoprotectant compounds that lower the point at which their body fluids freeze. Peer-reviewed cold-tolerance research on overwintering spider stages documents supercooling points as low as roughly -33°F for cold-hardened juveniles — meaning the animal that survives your New Hampshire winter in the leaf litter is already a living spider, just one equipped with a genuine antifreeze system, not a dormant egg waiting passively for spring.

Because the correction here is less dramatic than the rodent pages, it's tempting to treat the spider page as trivia. But the practical cost is real: believing indoor spiders are seasonal drives people toward winter pest treatments aimed at an animal that was never coming from outside, wasting effort on prevention against an event that isn't happening. Worse, it removes a genuinely useful predator — house spiders eat other small indoor insects — for no actual benefit. The honest winter action for the vast majority of NH homes is simply reducing clutter and vacuuming, not treating.