Are Daddy Long-Legs the Most Venomous Spider? The Arachnid Truth
False on two counts. The most common "daddy long-legs" — harvestmen (order Opiliones) — are not spiders and produce no venom whatsoever. Cellar spiders (Pholcus), which are true spiders, have venom but it is mild, not the most potent known.
"Daddy long-legs are the most venomous spiders in the world, but their fangs are too small to penetrate human skin." is a myth. The scientific consensus is clear, the primary sources are documented above, and the claim does not survive scrutiny. Read on for the full evidence.
"Daddy long-legs are the most venomous spiders in the world, but their fangs are too small to penetrate human skin."
Harvestmen (the most common "daddy long-legs") are not spiders and have no venom glands. Cellar spiders are true spiders with mild venom. Neither claim in the myth is accurate.
Few myths have achieved the longevity and confidence of the daddy long-legs claim. It is repeated by children, parents, and even some teachers with great certainty, often as a thrilling piece of hidden-danger trivia. The claim fails at the first check: the most commonly called "daddy long-legs" in most of the world — the harvestman — is not a spider. And it has no venom at all.
Three Very Different Creatures Share the Name
The name "daddy long-legs" is applied to three completely different arthropods depending on where you live. In most of the UK and Australia, it refers to crane flies — long-legged flying insects of the family Tipulidae. In most of North America, it refers to harvestmen (order Opiliones) — the brown, round-bodied creatures with eight extremely long legs that aggregate in corners and under logs. In some regions, it also refers to cellar spiders (family Pholcidae) — true spiders with long thin legs that build messy webs in house corners. Harvestmen are arachnids but not spiders; they are more closely related to mites and scorpions. They have no silk glands, no venom glands, and no fangs. They cannot bite in any meaningful sense.
What About Cellar Spiders?
Cellar spiders (Pholcus phalangioides and relatives) are true spiders with genuine fangs and functional venom. They regularly kill and eat other spiders, including species larger than themselves. The "most venomous" claim presumably refers to this group. However, cellar spider venom has been tested and found to be relatively mild. It is toxic to insects and effective for subduing prey, but it does not rank among the most potent venoms in any scientific comparison. A 2004 episode of the TV programme MythBusters had Adam Savage allow a cellar spider to bite him; he reported only a very mild, short-lived burning sensation. Their chelicerae (fangs) are perfectly capable of piercing human skin — the "can't bite humans" part of the myth is also incorrect.
Where Did the Myth Come From?
The origin is unclear, but the most plausible explanation is that the myth evolved as a piece of folk-safety reasoning: these are harmless creatures that look potentially dangerous, so the mythology framed them as secretly deadly but conveniently unable to harm us. A similar psychological mechanism produces myths about koalas (harmless appearance) and other familiar but potentially misunderstood animals. The claim also perpetuates because it is essentially unfalsifiable to casual listeners — the "but can't bite humans" rider makes it impossible to disprove through personal experience.
The Verdict
Harvestmen (the most common "daddy long-legs") have no venom — not mild venom, no venom. They cannot bite. They are harmless. Cellar spiders are true spiders with real but mild venom and fangs capable of piercing skin. Neither creature is the world's most venomous anything. The myth is false in every version.
Primary Sources
- [1] Pinto-da-Rocha, R. et al. (eds) (2007). Harvestmen: The Biology of Opiliones. ↗ Source
- [2] Zobel-Thropp, P.A. et al. (2014). Venom composition and toxicity of Pholcus phalangioides. ↗ Source
- [3] Bertone, M. & Burke, R., Burke Museum of Natural History (2010). Spider Myths: daddy long-legs. ↗ Source
Frequently Asked Questions
Are daddy long-legs the most venomous spider?
No. Harvestmen (the most common "daddy long-legs") are not spiders and produce no venom at all. Cellar spiders are true spiders with venom, but it is mild — not the most potent known. The "most venomous but can't bite humans" claim is false in both parts.
Can daddy long-legs bite humans?
Harvestmen cannot bite in any meaningful way — they have no venom or genuine fang apparatus. Cellar spiders can bite humans, though they rarely do. Adam Savage of MythBusters allowed one to bite him on camera; he reported a brief mild burning sensation that faded quickly.
Are harvestmen spiders?
No. Harvestmen (order Opiliones) are arachnids but not spiders. They differ from spiders in having their body segments fused (spiders have a distinct head-thorax and abdomen), no silk glands, no venom glands, and only two eyes. They are more closely related to mites and scorpions than to true spiders.
What is the most venomous spider in the world?
By toxicity, the Sydney funnel-web spider (Atrax robustus) and Brazilian wandering spider (Phoneutria) are often cited as the most dangerous to humans. The inland taipan snake produces the most toxic venom of any land animal, but among spiders, funnel-webs and wandering spiders are considered most dangerous based on documented human effects.
What do harvestmen eat if they have no venom?
Harvestmen are omnivores that eat small invertebrates, dead insects, fungi, plant material, and decaying organic matter. Rather than injecting venom to subdue prey, they use their chelicerae (small pincers) to mechanically manipulate and consume food. Some species will scavenge on carcasses.
How We Verified This Claim
SmartAss Facts evaluates every popular belief against a three-tier source hierarchy: primary sources (peer-reviewed research, government datasets, and institutional reports), secondary sources (reputable journalism citing the primary), and tertiary sources (general reference). Only primary sources are cited.
For this myth — Daddy long-legs are the most venomous spiders in the world, but their fangs are too small to penetrate human skin. — we reviewed the cited primary sources above, cross-referenced against independent scientific literature, and confirmed the verdict with the consensus position of relevant scientific bodies. Last reviewed: 2026-05-25.
More Myths Debunked
Every claim below has been examined against primary sources. Each one turned out to be false.