Are Daddy Longlegs Venomous? The Famous Myth Explained

Which animal is the “daddy longlegs”?

The answer depends on where you live, because three quite different animals share the nickname:

In North America, “daddy longlegs” usually means a harvestman, such as the common harvestman or the eastern harvestman. In Britain and Ireland the name usually means the crane fly, the gangly flying insect that blunders into lit rooms in late summer. Many people everywhere also use it for the cellar spider, the thin, pale spider that hangs upside down in loose webs in corners.

Harvestmen have no venom at all

Harvestmen are arachnids, related to spiders, but they belong to a separate order. Not one of the more than 6,600 known species has venom glands. Their mouthparts, called chelicerae, are small pincers used to grab and tear food, not hollow fangs that inject anything.

This is why the myth fails completely for harvestmen. They are not holding back a deadly venom because their fangs are too short; they simply have no venom to deliver. They also do not spin silk or build webs.

Harvestmen do have a chemical defense, but it is not venom. A pair of scent glands near the front of the body releases a strong-smelling fluid when the animal is grabbed. In some species it contains irritating compounds called quinones. It makes harvestmen taste bad to ants, spiders and other predators, but it is not dangerous to people.

Cellar spiders: venomous, but not dangerous

Cellar spiders, including the common Pholcus phalangioides, are true spiders, and like almost all spiders they use venom to subdue prey. Their venom works well on insects and other spiders, including some much larger than themselves. This hunting reputation probably helped feed the idea that their venom must be extremely powerful.

There is no scientific evidence, however, that cellar spider venom is unusually strong for mammals, and no record of it causing serious harm to a person. Their fangs are short, and bites to people are very rare. In a widely seen 2004 episode of the TV show MythBusters, a presenter let a cellar spider bite him and reported only a faint burning feeling that faded within seconds.

The claim “most venomous but can’t bite” therefore mixes up two separate questions. How toxic a venom is to insects says little about its effect on humans. To compare cellar spiders with spiders that really matter medically, see are all spiders venomous? and our list of the most venomous spiders.

Crane flies cannot bite or sting

Crane flies are true flies with two narrow wings and very long, fragile legs. Adults have no venom, no stinger and no biting mouthparts. Many adult crane flies feed little or not at all during their short adult life, which is focused on mating and laying eggs.

Crane flies are often mistaken for giant mosquitoes, and some people call them “mosquito hawks,” but they do not suck blood and they do not eat mosquitoes. Their larvae, sometimes called leatherjackets, live in soil and lawns, and those larvae cannot hurt people either.

Where did the myth come from?

Nobody knows exactly how the story started, but it spread widely by word of mouth and was repeated in school playgrounds and on the internet for decades. Its appeal is easy to see: it turns a harmless, fragile-looking animal into a secret menace and offers a neat explanation for why nobody is ever hurt.

Part of the confusion comes from the shared name. A fact about one “daddy longlegs” is easily applied to another. Harvestmen have no venom, so the claim cannot be about them. Cellar spiders do have venom, but it has never been measured as the most potent in the world, and no study has shown it to be dangerous to people. Crane flies have nothing to do with venom at all.

Why daddy longlegs are good neighbors

Rather than fearing them, many naturalists welcome daddy longlegs. Harvestmen eat aphids, caterpillars, mites, small insects and dead material in gardens and fields. Cellar spiders catch flies, mosquitoes and other spiders, including some that people find less welcome indoors. Crane flies are an important food for birds, bats and frogs.

None of them spreads disease or damages buildings. The kindest and simplest approach is to leave them alone or gently move them outdoors. Handling a harvestman roughly can make it drop a leg, a defense explained in why do daddy longlegs lose their legs?, and lost legs never grow back.