When temperatures drop and days shorten, many wonder what becomes of the spiders abundant during warmer months. Spiders, being cold-blooded, rely on their environment to regulate body temperature, which impacts their activity. Their survival through colder seasons involves adaptations allowing them to endure otherwise inhospitable conditions.
How Spiders Survive Cold
Spiders employ various physiological mechanisms to survive freezing temperatures. Many species produce cryoprotectants, such as glycerol, in their hemolymph (spider blood) as autumn approaches. These substances act as a natural antifreeze, lowering the freezing point of their bodily fluids and preventing ice crystals from forming inside their cells, a process known as supercooling. Some spiders can withstand temperatures as low as -20°C due to these adaptations.
Beyond chemical adaptations, spiders undergo a metabolic slowdown, often referred to as diapause. Their metabolic rate significantly decreases, allowing them to conserve energy when food sources are scarce and temperatures are low. Bodily functions, including respiration and digestion, slow down considerably, enabling them to survive for extended periods without sustenance.
Where Spiders Go in Winter
Spiders seek out sheltered locations to escape the harshest cold. Outdoors, common hiding spots include under rocks, within leaf litter, beneath loose tree bark, or inside hollow plant stems. These natural shelters offer insulation from wind, extreme cold, and precipitation, creating stable microclimates. Some species may burrow into the top layer of soil or construct silk-lined retreats in crevices for protection.
Certain spider species may also seek refuge in human dwellings when outdoor temperatures plummet. They can be found in undisturbed areas like attics, basements, wall voids, and crawl spaces where temperatures are more consistent. Spiders typically seen indoors are often house species adapted to indoor living, not usually migrating inside from outdoors solely for winter. Releasing a house spider outdoors in winter would likely result in its demise.
Spider Activity During Cold Months
During colder months, most spiders become largely inactive, entering diapause. This reduced activity minimizes their energy expenditure and exposure to potential threats. While not in full hibernation like some mammals, their movements and bodily functions are significantly slowed.
Some spiders, particularly those overwintering as adults or juveniles, may occasionally emerge from their shelters on warmer winter days. They might briefly hunt for available prey during these milder periods. Active hunting and extensive web-building largely cease for most species, as prey is scarce and the energy cost is high. A small percentage of species, such as some Linyphiidae, can remain active even below 0°C, maintaining webs and catching prey.
The Fate of Spider Eggs
The survival of spider eggs through winter is a crucial aspect of their life cycle. Many species lay their eggs in protective silk sacs during late summer or fall. These egg sacs are designed to shield developing embryos from harsh environmental conditions.
Female spiders typically place these sacs in sheltered locations, such as under bark, in rock piles, beneath leaves, or attached to vegetation. The silk provides insulation, and some female spiders may remain with their egg sacs to offer additional warmth and protection until they die. Spiderlings generally hatch in spring, emerging when temperatures rise and food sources become more readily available.