Cellar spiders, belonging to the family Pholcidae, are often called “Daddy Long-Legs Spiders.” These arachnids are commonly found in homes across the globe, frequently hanging in the dusty corners of rooms and garages. This article examines the physical realities of cellar spiders, analyzing the likelihood and potential medical outcome of a bite.
Identifying Cellar Spiders and Their Range
Cellar spiders are identified by their distinct, fragile appearance, characterized by extremely long, thin legs attached to a small, often translucent body. The body typically measures between six and eight millimeters, but the legs can span up to five or six times that length. The body color is generally a pale yellowish-brown or gray.
These spiders construct loose, irregular webs, often found in high corners or sheltered spaces. They are a cosmopolitan species found across the world, thriving in human-made structures. Cellar spiders prefer dark, damp, and undisturbed microclimates like basements, cellars, crawl spaces, and sheds.
The Mechanics and Likelihood of a Bite
Like most spiders, cellar spiders possess fangs (chelicerae) and venom glands, but this equipment does not translate into a threat to humans. The fangs are exceptionally small, typically measuring around 0.25 to 0.5 millimeters in length. This diminutive size makes it mechanically difficult for the spider to penetrate the relatively thick outer layer of human skin.
Bites are extremely rare because a cellar spider struggles to breach the skin. Biting usually only occurs under severe circumstances, such as when the spider is forcefully crushed against a person’s skin. Since they are non-aggressive and prefer to quickly vibrate their webs when disturbed, they do not actively seek out humans to bite.
The spider’s small mouthparts are adapted to subdue their typical prey, which consists of small insects and other spiders. When hunting, they primarily rely on silk to ensnare and immobilize their victim before biting. This reliance on silk over immediate venom injection demonstrates that their offensive mechanisms are not geared toward large mammals.
Medical Outcome and Common Misconceptions
If a successful bite were to occur, the medical consequence to a human is minimal. Documented instances suggest the result is a mild, localized reaction, similar to a pinprick or a slight sting. Symptoms may include brief, localized redness or minor irritation at the site of the bite, with no systemic or lasting effects.
The most persistent misconception is the urban legend that the cellar spider is the most venomous spider in the world, but its fangs are too small to harm a person. This is not supported by scientific evidence, as their venom is weak compared to medically significant species. While effective against insect prey, the venom is not potent enough to pose a danger to human health.
This myth likely originated because cellar spiders prey on more dangerous spiders, such as black widows. They overpower these larger arachnids not through venom strength, but by using their long legs to quickly wrap them in silk. One study analyzing the venom of a Pholcid species found its strength to be less than two percent of that of a brown recluse spider’s venom.