Unlike stories shared on the playground, daddy long legs are not venomous and their mouthparts are too small to pierce human skin. Daddy long legs are also known to congregate in large masses with their legs interlaced. When disturbed, they shake violently, causing the mass to vibrate.

Why do daddy long legs vibrate?

Daddy long legs spider - Pholcus phalangioides

If disturbed they vibrate in their webs, which is probably a way to frighten predators. They feed on any insects found in homes and will also take other spiders, including surprisingly large house spiders (Tegenaria species).

What does it mean when daddy long legs bounce?

Bobbing. To deflect attacks and enhance escape, long-legged species – commonly known as daddy long-legs – from the Eupnoi suborder, use two mechanisms. One is bobbing, for which these particular individuals bounce their bodies.