Owing to the length of their legs, pholcids are often called daddy long-legs, a colloquial label that is also used for the similarly long-legged and distantly related harvestmen. Unlike harvestmen, pholcids are true spiders, complete with web-building tendencies, two discrete body sections, and venom glands—although their venom is only mildly toxic to humans.
Cellar spiders are denizens of dark, damp, and undisturbed places, such as your basement and the nether regions behind that dresser you haven’t moved in years. Left to their own devices, they can cover considerable areas with silken tendrils as they continuously add to their lairs. There they wait for victims to blunder into the haphazardly constructed webs. Their awkward appearance belies their agility; they move with dazzling speed to wrap prey—including insects such as ants and roaches—in silk. In fact, pholcids are so adept in webs that they raid other spiders’ webs to steal prey or even eat the current inhabitants.
Not being content to simply eat their fellow spiders, cellar spiders also outperform them. When disturbed in their webs, cellar spiders gyrate wildly—a behavior that may blur their silhouettes to confuse potential predators or flex and slacken their webs to further entangle prey. Either way, their dancing definitely makes them worthy of observation, if not entirely justifying their presence indoors.