The myth surrounding the “Daddy Long Legs” suggests it possesses the world’s deadliest venom but cannot bite humans due to its tiny fangs. This belief is often intertwined with the claim that this creature is a natural predator of the highly venomous Black Widow spider. To understand the truth, it is necessary to clarify which animal is being discussed, as the common name “Daddy Long Legs” refers to multiple distinct species. This clarification reveals the scientific mechanisms that allow one of these creatures to successfully hunt and kill the Black Widow, despite having relatively mild venom.
Defining the Name: Harvestmen vs. Cellar Spiders
The confusion over the “Daddy Long Legs” nickname stems from its application to multiple arthropods. The first group, Harvestmen (Order Opiliones), are not true spiders, possessing a single, fused body section instead of two. Harvestmen lack both venom glands and silk-producing spinnerets. They are primarily scavengers that feed on decaying matter, small insects, and fungi, making them incapable of killing a Black Widow.
The second group, the Cellar Spiders (Family Pholcidae), are true spiders and the actual subject of the Black Widow predation myth. These spiders are characterized by their extremely long, thin legs and are frequently found hanging upside down in messy, irregular webs in damp, dark areas like basements and cellars. Cellar Spiders possess venom and silk, which they use for predatory behavior against other spiders. Their success in killing Black Widows likely fueled the myth that they are the “most venomous spider.”
The Direct Answer: Cellar Spider Predation on Black Widows
The scientific truth is that Cellar Spiders, the true spiders referred to as “Daddy Long Legs,” do kill and consume Black Widow spiders. This predatory success is not due to superior venom, but rather a specialized hunting strategy. A Cellar Spider will deliberately venture onto the Black Widow’s strong, sticky web, which is typically built in a protected location.
Once on the web, the Cellar Spider uses its long legs to maintain distance while rapidly deploying fresh, non-sticky silk. This silk quickly entangles and immobilizes the much larger opponent. The Black Widow’s defense of throwing sticky silk is rendered ineffective against the attacker’s speed and reach.
After the Black Widow is completely wrapped and unable to move, the Cellar Spider approaches to deliver a bite, often targeting a vulnerable joint. This hunting method, known as araneophagy (spider-eating), is common for Cellar Spiders in areas where they coexist with Black Widows. The ability of the Cellar Spider to overpower a medically significant spider is the origin of its reputation for having potent venom.
Venom Capabilities and Human Risk
The myth that “Daddy Long Legs” possess deadly venom that their fangs cannot deliver to humans is false, especially regarding the Cellar Spider. Cellar Spiders are venomous, as are nearly all spiders, but their venom is considered relatively mild. Scientific studies show that Cellar Spider venom is significantly weaker than that of a Black Widow, and only a tiny fraction of the potency of Brown Recluse venom.
The idea that Cellar Spiders cannot bite through human skin is also inaccurate; they possess fangs and are capable of piercing the skin. When a bite occurs, typically only under duress, the effect is inconsequential, resulting in a mild, short-lived sting with no long-lasting effects. In contrast, the Black Widow’s venom contains a neurotoxin that can cause latrodectism in humans, characterized by severe muscle pain, cramping, and other systemic symptoms, making its bite medically significant.