“Daddy longlegs are the most venomous spiders”

The widespread belief that "daddy longlegs" are the most venomous spiders in the world, but simply can't bite humans, is a persistent misconception. This myth often stems from a confusion over which creature the common name "daddy longlegs" actually refers to, as it's used for at least two very different arachnids, leading to a conflation of their characteristics.

Scientifically speaking, the creatures most commonly known as harvestmen (order Opiliones) are not spiders at all. While they are arachnids, like spiders, harvestmen completely lack venom (Review) glands and fangs, making it impossible for them to produce or inject venom. Therefore, they pose absolutely no threat to humans in terms of toxicity. The other creature sometimes called a "daddy longlegs" is the cellar spider (family Pholcidae). These *are* true spiders and possess venom, but their venom is extremely mild and has no significant effect on humans.

The enduring nature of this myth likely arises from several factors. The long, spindly legs and sometimes shadowy presence of both harvestmen and cellar spiders can evoke a sense of unease. Without clear information, it's easy to conflate the two distinct groups under a single, misleading name and then attribute exaggerated danger to them. The idea that something could be incredibly dangerous but conveniently harmless because of a physical limitation (like not being able to bite through skin) is also a compelling narrative that helps the myth spread, despite lacking scientific basis.