Is the Daddy Longlegs Dangerous to Humans?

Many people believe that daddy longlegs are deadly, or at least venomous. It's also common to hear that the only reason they aren't a threat to humans is that their fangs are too short to penetrate human skin. The fact that this information is repeated so often causes many people to assume that the statements must be true.

The truth, however, is that you do not need to fear daddy longlegs. It's also true that when two people are discussing "daddy longlegs," they might not be talking about the same creature.

Daddy Longlegs

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Daddy Longlegs: Arachnids, but Not Spiders

By Debbie Hadley

Three kinds of critters are commonly referred to as daddy longlegs, two of which are not spiders, and one of those two is not even an arachnid.

• The common name daddy longlegs is most often used to describe Opiliones, which are also known as "harvestmen." Opiliones are arachnids but not spiders. They have no venom glands and do not spin webs. They prefer moist environments, such as under logs and rocks, though some can be found in desert climates.
• The nickname might also refer to a crane fly, which is a true fly and a member of the order Diptera. They have six legs and wings and look like gigantic mosquitoes. Crane flies are not spiders or arachnids and do not pose a threat to people.
• Sometimes, the name daddy longlegs is used for a group of spiders of the family Pholcidae. These spiders are commonly called cellar spiders, and they do have venom glands. One common cellar spider found across the United States is Pholcus phalangioides and is gray. Another is Holocnemus pluchei, common on the Pacific Coast and in desert areas. It has a brown stripe on its abdomen. Both of them spin webs.

Are Cellar Spiders Harmful?

Even though cellar spiders have venom glands, there is no scientific evidence that their venom can harm a human being. No studies have been done on cellar spider venom to measure its toxicity, according to spider experts at the University of California-Riverside.

Pholcid spiders do have short fangs, but no shorter than those of other spiders that have been known to bite humans. The cellar spider's fangs are similar in structure to those of a ​brown recluse spider, which often bites humans. 

The show "Mythbusters" tackled the daddy longlegs fangs legend back in 2004. Co-host Adam Savage subjected himself to a cellar spider bite, proving that this "daddy longlegs spider" is indeed capable of breaking human skin.

The results? Savage reported nothing more than a mild, short-lived burning sensation. Analysis of the venom revealed it is nowhere near as potent as venom from a black widow spider, which can kill people, though most people who are bitten recover in 24 hours. Not all people who are bitten by a black widow spider receive venom. Some people just get a bite.

All of this means that you do not need to worry about bites from daddy longlegs of any variety.