Is Daddy Longlegs Venomous?

Daddy Longlegs (Opiliones)

Ed Reschke / Photolibrary / Getty Images 

Many people believe that daddy longlegs is deadly or at least venomous. It's also common to hear that they can't bite humans because their fangs are too short to penetrate the skin. The fact that this information is repeated so often causes many people to assume that the sayings must be true. However, the real truth is that you do not need to fear "daddy longlegs." When discussing "daddy longlegs," two people may not even be talking about the same creature.

What You Should Know About the Daddy Longlegs

First of all, there are three kinds of critters that are commonly called daddy longlegs, two of which are not spiders, one of which isn't 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 at all, do not spin webs, and are not venomous. They prefer moist environments, such as under logs and rocks, though some can be found in desert climates.
  • The nickname "daddy longlegs" may 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 do not pose a threat to people either.
  • Sometimes, the name "daddy longlegs" or "daddy longlegs spiders" is used for a group of arachnids, the spiders of the family Pholcidae. These spiders are also 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 spin webs.

    Can Cellar Spiders Harm You?

    Even though cellar spiders have venom glands, there is no scientific evidence whatsoever to confirm 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 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 can and does bite humans. 

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

    The results? Savage reported nothing more than a very mild, short-lived burning sensation. Analysis of the daddy longlegs' venom revealed it's 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 receive venom from the black widow spider, either. Some just receive a bite. That means that you don't need to worry about daddy longlegs of any variety.