The most persistent myth surrounding “daddy longlegs” is that they are the world’s most venomous spider, but their fangs are not big enough to bite through human skin.
Daddy longlegs are not spiders
They are properly called “harvestmen,” and are in the order Opiliones. They are related to spiders in the sense of being arachnids like spiders, mites, and scorpions. Cellar spiders and crane flies are also called daddy longlegs, but harvestmen do not spin webs and do not have wings.
Daddy longlegs are not venomous
Harvestmen do not have venom glands, or fangs. They scavenge dead organic matter, are opportunistic predators on injured invertebrates, or both. No one knows for sure.
They do have chemical defenses
Grab a daddy longlegs and it is likely to secrete droplets of a milky-white liquid designed to repel all but the most determined predators. They also shed their legs at will. Better to lose a leg or two than your life. Young harvestmen that lose a leg may regenerate the facsimile of a new one when they molt (shed their exoskeleton to grow).
There is apparently no correct spelling
“Daddy longlegs” is also routinely spelled “daddy long-legs,” “daddy-longlegs,” or even “daddy-long-legs.” Now you have another reason to use the proper name “harvestman.”
More myths and folklore
One old wives’ tale held that if you killed a daddy longlegs it would rain the next day.
Another piece of folklore suggested using a harvestman to find your lost herd of cattle: Pick up a daddy longlegs by all legs but one, and that free leg will point you in the direction of your wayward livestock.
The county of Essex, England, had its own mythology surrounding harvestmen in the 1600s. According to this myth, each daddy longlegs possessed a scythe they would use to help local farmers harvest crops. Killing a “harvestman” was thus bad luck.
According to an old French peasant legend, seeing a daddy longlegs in the evening is a good thing, foretelling good fortune, happiness, and hope. Sounds better than the seriously venomous spider myth.