The black widow spider (Latrodectus) is well-known for its potent venom and distinctive appearance. Although these spiders thrive in warmer climates, they have developed specific adaptations to survive cold weather. They do not perish with the first frost but instead seek protected microclimates to ensure their survival. Understanding this cold-weather strategy reveals that their absence is a temporary retreat rather than a die-off.
Surviving the Cold: The Dormant Stage
When temperatures consistently drop, black widow spiders enter a state of reduced activity known as dormancy or overwintering. This survival mechanism involves a significant slowdown of the spider’s metabolic rate, which conserves the energy needed to live through months without available prey. Spiders often tuck in their legs and curl up tightly to minimize surface area exposure to the cold.
While adult males typically die off as winter approaches, the adult female and immature spiderlings are the primary overwintering stages. The tightly woven, silken egg sacs are also crucial for survival, protecting hundreds of developing spiderlings until warm weather allows them to complete their development.
Common Winter Shelters and Retreats
Black widows actively search for environments that offer stability, insulation, and protection from freezing temperatures and moisture. Their preferred winter retreats are dark, secluded, and dry locations that buffer against drastic temperature swings.
Outdoors, they commonly seek shelter in stable locations such as:
- Deep within woodpiles.
- Under rocks or patio furniture.
- Inside hollow logs.
- Within utility or irrigation valve boxes.
The spiders frequently move into man-made structures as the weather turns cold, as these often offer superior insulation. Garages, sheds, barns, and outhouses are common locations, especially in cluttered corners or beneath stored items that remain undisturbed. Indoors, they may inhabit basements, attics, and crawl spaces. These indoor locations can sometimes be warm enough that the spiders remain semi-active, feeding occasionally if other pests are present.
When Black Widows Become Active Again
The return to activity is directly linked to a sustained rise in ambient and ground temperatures, which typically occurs in late spring or early summer. Black widow spiders generally become most active when temperatures reach approximately 50°F and higher. The warming weather increases their metabolic rate, prompting them to leave their dormant state and begin searching for food.
The end of the overwintering period signals the start of the breeding cycle and dispersal. Juvenile spiders that survived the winter complete their development into mature adults in the spring. Females begin constructing larger, more complex webs to capture prey and attract mates, leading to the production of new egg sacs and the continuation of the species’ life cycle.