The common cellar spider, belonging to the family Pholcidae, is a familiar sight in homes due to its extremely long, thin legs and small, yellowish-gray body. This appearance often leads to its misidentification as a harvestman or crane fly, both of which are sometimes called “daddy long-legs.” Cellar spiders typically construct messy, irregular, tangled webs in dark, undisturbed areas like basements, sheds, and attics. The central question about this arachnid is whether it preys on other spiders, a behavior that is surprisingly common for this species.
Specialized Spider Predators
The answer to whether cellar spiders eat other spiders is a definitive yes. This diet focused on other arachnids is known scientifically as araneophagy, placing them among a specialized group of predators. The Pholcidae family is adapted to this lifestyle, making their presence a natural form of pest control against other, sometimes larger, spider species. Cellar spiders thrive in stable, enclosed environments like basements, where they compete directly with other resident spiders for resources. Hunting other spiders gives them a substantial advantage in these confined spaces, ensuring a steady food supply.
Hunting Techniques and Preferred Prey
Cellar spiders use sophisticated and deceptive hunting techniques that allow them to overcome prey significantly larger than themselves. Their most well-documented strategy is aggressive mimicry, where they invade another spider’s web and pluck the silk strands. By vibrating the web in a specific rhythm, the cellar spider mimics the struggles of a trapped insect, luring the unsuspecting web owner closer.
Once the host spider approaches, the cellar spider attacks by rapidly casting long swaths of silk over the victim from a safe distance. Their exceptionally long legs allow them to wrap and bind the prey securely without engaging in a direct, close-quarters struggle. After the victim is completely immobilized in silk, the cellar spider moves in for the venomous bite. This wrapping technique is so effective that cellar spiders are known to take down notoriously dangerous species, including black widows and hobo spiders.
Beyond the Web: Other Dietary Sources
While their preference and specialization lean toward araneophagy, cellar spiders are opportunistic hunters and will consume other small arthropods when spiders are scarce. Their messy, tangled webs lack the adhesive properties of other spider silks, but are still effective at trapping various small insects. Prey that gets tangled in the complex matrix of threads quickly becomes a meal.
The cellar spider’s diet includes common household pests like flies, mosquitoes, and mites. They are also known to eat ants and other small insects that happen upon their web. Furthermore, they have been observed scavenging, consuming dead arthropods they encounter. Although they will readily eat these other prey items, the cellar spider’s primary ecological role remains that of a specialized spider predator.