The cellar spiders are often called “Daddy Long-legs” due to their very long, thin legs. However, the true Daddy Long-legs is another animal entirely, called the Harvestman. The cellar spiders are incapable of biting humans and are harmless to us and our pets. Their primary crime is the messiness of their webs, which are thin and flimsy but tend to gather dust and floating debris, as well as the remains of the insects the spiders have fed on. Webs typically appear under the eaves of roofs, around porch lights, within garages, and indoors around windows where the light may draw small insects that the spiders feed on. Their long legs make them very clumsy when attempting to walk. They hang upside down on their webs, and when disturbed they will begin to shake and bounce the web noticeably, or they may drop off the web and run to hide. These spiders have been known to feed on black widow spiders. The female creates an egg mass of about a dozen eggs, and holds it in her jaws until the eggs hatch.
Sweeping of webs to remove them is an important step in cellar spider control, as these spiders do not reuse their own silk, and the webs continue to accumulate. Sweeping is not likely to kill the spiders, but pyrethroid insecticides provide excellent knockdown and control. Reduction of other insects in and around a home will reduce the food available to the spiders, and removal of debris and lumber piles will help to reduce harborage sites. Reduction of outdoor lighting or changing white light bulbs to yellow will help to attract fewer night-flying insects and thus reduce the spider populations.