“Daddy longlegs are the most venomous spiders but their fangs are too small to bite humans”

The enduring misconception that daddy longlegs are the world's most venomous spiders, but harmless to humans due to tiny fangs, stems from a common misidentification and the spread of urban legends. The term "daddy longlegs" is actually used interchangeably for two distinct types of arachnids, leading to significant confusion about their biological characteristics and potential danger. This ambiguity has allowed the myth to thrive, blending facts from one creature with the exaggerated dangers of another.

The creature most accurately referred to as a "daddy longlegs" is the harvestman, an arachnid belonging to the order Opiliones. Unlike true spiders, harvestmen have a fused body and, most importantly, possess no venom (Review) glands whatsoever. Their mouthparts are designed for scavenging and consuming decaying matter or very small, soft-bodied insects, not for injecting toxins. Therefore, any claim about their venom potency is completely baseless, as they simply do not produce venom.

The other arachnid sometimes called a "daddy longlegs" is the cellar spider, a true spider from the family Pholcidae. These spiders do indeed have venom glands and fangs capable of piercing human skin. However, scientific research indicates that their venom is quite mild, primarily effective against their insect prey, and not considered dangerous to humans. While a bite might occur, any symptoms are typically minor, often less significant than a mosquito bite or bee sting. The myth likely gained traction by conflating the visual appearance of cellar spiders with the non-venomous harvestman, then adding a sensational, unfounded claim about extreme venom.