Black widow spiders, recognized by the distinct red hourglass marking on the underside of the female’s abdomen, are renowned for their potent venom. While their bite can cause muscle pain, nausea, and other symptoms in humans, fatalities are rare. Despite their reputation, black widows are not at the top of the food chain and play a role within their ecosystems, primarily by controlling insect populations. These spiders, found globally, construct messy, irregular webs typically low to the ground in sheltered, dry places like woodpiles or basements. The female’s prominent marking serves as a warning to potential predators.
Invertebrate Predators
Invertebrate species prey on black widow spiders. Mud dauber wasps, including the blue mud dauber, are significant predators. These wasps paralyze black widows with their sting and transport them to their nests to feed their larvae.
Other spiders prey on black widows. Cellar spiders, sometimes called daddy long-legs spiders, hunt and consume black widows. They use their long legs and dense, cage-like webs to entangle and subdue black widows, even though their own venom is comparatively mild. Praying mantises are another insect predator that can overpower and consume black widows, especially if larger than the spider.
Vertebrate Predators
Vertebrate animals prey on black widow spiders. Certain lizard species, such as alligator lizards and western fence lizards, consume them. Alligator lizards, in particular, are highly resistant to the black widow’s venom. Lizards may encounter black widows while foraging for other prey.
Birds, especially ground-feeding varieties, occasionally prey on black widows. While many birds might experience stomach upset from the spider’s toxins and avoid them, some still opportunistically consume them. Small mammals, such as shrews and mice, might also prey on black widows if the opportunity arises. Amphibians like frogs and toads can also become predators if black widows become entangled in their webs.
Predator Adaptations
Predators of black widows exhibit adaptations and strategies to overcome the spider’s potent venom and defensive behaviors. Some animals possess a natural resistance or immunity to the venom’s effects. For instance, alligator lizards show remarkable tolerance; studies indicate their muscles remain unaffected even by lethal doses. This suggests a physiological mechanism, possibly involving specialized proteins that neutralize toxins.
Physical attributes also play a role in successful predation. Predators with thick exoskeletons, shells, or scales may have a degree of physical protection against bites. Hunting techniques are often crucial; mud dauber wasps, for example, paralyze the spider with a precise sting, preventing it from biting. Other predators, like cellar spiders, use their unique web structure to entangle black widows, allowing them to subdue the prey without direct contact until it is incapacitated. These combined adaptations enable various animals to safely consume black widow spiders, integrating them into the broader food web.