A persistent urban legend claims the “daddy long legs” is the most venomous creature in the world, but that its fangs are too small to pierce human skin. This vivid, yet entirely inaccurate, claim suggests a hidden potency in a common household arachnid. This misconception has made the animal a subject of curiosity and fear, but the scientific reality is far less dramatic. To address the question of how venomous a daddy long legs is, it is necessary to first understand exactly which creature is being discussed.
Clarifying the Three Creatures Called “Daddy Long Legs”
The difficulty in answering the question of venom lies in the fact that the common name “daddy long legs” is used for at least three distinct types of animals. Only one of these is a true spider; the others are separate classes of animals. The identification is split between two arachnids and one insect.
One creature commonly given this name is the Harvestman, an arachnid but not a spider, belonging to the Order Opiliones. The second is the Cellar Spider, a true spider belonging to the Family Pholcidae. Finally, the name is sometimes used for the Crane Fly, a large insect. Since crane flies are insects and lack the necessary mouthparts to bite, they are irrelevant to the venom question.
The distinction between the two arachnids is necessary for an accurate assessment of the venom myth. A Harvestman’s body is fused into a single oval shape. In contrast, the Cellar Spider, like all true spiders, has a segmented body with a clear separation between the cephalothorax and the abdomen. The presence and potency of venom varies drastically between these two groups.
Harvestmen: The Non-Spiders
Harvestmen (Opiliones) are the creatures most often mistakenly associated with the venom myth, yet they possess no venom. These arachnids are easily identified by their single, fused body section, which lacks the narrow waist found in spiders. They are not true spiders because they lack venom glands, silk-producing spinnerets, and the two-part body structure that defines the Order Araneae.
Harvestmen use chelicerae, which are small, pincer-like mouthparts designed for grasping and tearing food, not for injecting toxins. They are primarily scavengers, feeding on small insects, dead organisms, and plant matter. The absence of venom glands means they are biologically incapable of producing the toxins necessary to support the urban legend.
Some species of Harvestmen secrete a foul-smelling chemical when disturbed, which is a defense mechanism against predators. This chemical defense works by contact or ingestion, not as an injected venom. Therefore, the myth is entirely false for the Harvestman; they are completely harmless to humans and have no capacity to envenomate.
Cellar Spiders: The True Spiders
The Cellar Spider is a true spider and possesses venom glands and fangs. These spiders (Family Pholcidae) are often found dangling from their irregular webs in basements and dark corners. Their venom is primarily used to subdue the small insects and other spiders they catch, including medically significant species like the Black Widow.
Scientific analysis shows Cellar Spider venom contains proteins and neurotoxins potent against their insect prey. However, the venom is medically insignificant to mammals, including humans. Documented human bites from Cellar Spiders are rare and typically occur only when the spider is severely provoked. These bites have resulted in nothing more than a minor, short-lived stinging sensation.
The myth that their fangs are too short to pierce human skin is overstated, as some species’ fangs are structurally similar to those of the Brown Recluse. While they can sometimes penetrate the skin, the effect is negligible due to the venom’s low toxicity to our system. The overall consensus is that while the Cellar Spider is venomous, its venom poses no threat to human health, debunking the urban legend.