Not all spiders die during the winter. While they are cold-blooded, they have adapted several ways to survive the cold seasons. Some overwinter in egg sacs, others take shelter, and others actually produce an antifreeze-like chemical inside their bodies that lowers their freezing temperature.
What Temperatures do Spiders Prefer?
Spiders are a very diverse species and can be found everywhere on Earth except Antarctica. Because of their adaptability, it is difficult to nail down an ideal temperature range, but like most insects, once the temperature starts to dip below 50 degrees F consistently, they begin to slow down.
Most insects, including spiders, prefer temperatures around 70 degrees F, and spiders tend to be more active during the spring and fall months. Depending on the species, spring and fall is when spiders are maturing, mating, and laying their own eggs.
When temperatures become too hot or too cold, spiders become less active, either seeking shelter or, in the case of certain species, beginning to slowly lower their freezing point.
How do Spiders Survive During the Winter?
Some spiders can tolerate temperatures as cold as -5 degrees C, or about 23 degrees F — well below freezing. These spiders produce glycerol, which is similar to the antifreeze we put in our cars.
But it’s a slow process and it takes time for spiders to build up enough glycerol to survive the cold. So if you’re thinking about putting a spider you found outside to avoid killing them, you should reconsider. They won’t have built up the necessary cryoprotectant and will likely die.
When temperatures rise above 25 degrees F, these species of spider can become more active, hunting while the weather allows. You can sometimes see these spiders outside in the snow during a warm spell.
In Egg Sacs
Some spiders will lay their eggs in the fall. The eggs hatch, and then the spiderlings spend the winter inside the sac to stay warm. The spiderlings inside the sac also undergo cold hardening as the temperatures drop.
In the spring they emerge, mature, and will lay their own eggs the following fall.
Other spiders, including wolf spiders, jumping spiders, and running spiders, hatch in the spring. To survive the winter, they take shelter inside cracks and crevices, under leaf litter, and in spaces along the ground that stay warmer.
Some spiders also weave protective webs that they shelter in, and others build their webs in east/west facing patterns to better take advantage of the sun’s heat.
Can a Spider Infestation Happen During the Winter?
While you may notice a few extra spiders during the winter, it’s a myth that all spiders rush inside to avoid the cold. On the contrary, most outdoor spiders are not well adapted to survive inside where food and water are more scarce.
But some spiders, like the brown recluse do sometimes venture inside during the winter. Because they are venomous, brown recluse spiders can be concerning. If they do come inside, they typically find an out of the way spot to hide, like a forgotten corner of your garage or attic. But accidental bites can happen if they’re disturbed, so be careful.
Other spiders you’re likely to see in your home were most likely there the whole time. The American house spider, which is part of a group of cobweb spiders that build webs in common indoor areas like closets, basements, and crawl spaces, is a common house spider.
Other types of house spiders include long-bodied cellar spiders, or daddy longlegs, sac spiders, jumping spiders, wolf spiders, and hobo spiders. These spiders are well adapted to life inside and won’t survive being thrown out.
How to Eradicate Spiders During the Winter
Most of the time, spiders you spot inside during the winter are not harmful and are likely doing their part to keep indoor insect populations in check. Consider leaving them alone and letting them do their part for the good of the household. And most of them have probably been there the whole time and won’t survive being put out.
But if spiders are bothering you, you can transfer them to a barn or garage, where they’ll be out of your sight, but still sheltered from the weather. If you think your spider may be venomous, take precautions to avoid being accidentally bitten.
Once your spider has been “rehomed,” seal up any cracks or small openings with caulk to keep them from coming back in. Regularly vacuuming and keeping clutter picked up will also discourage spiders from taking up residence in high-traffic areas. Remember, they don’t want your attention and will seek out hidden areas of your home.