The Life Cycle of a Common House Spider

Male and female common house spiders frequently occupy the same web and, unlike many other species, will mate several times.

Females create silky, brownish egg sacs that are tough and paper-like on the outside. The sacs are oval-shaped or sometimes flask-shaped. In these sacs, the female will deposit about 250 eggs. A web may contain more than one egg sac at a time. In her lifetime, a female house spider can produce as many as 17 egg sacs.

The female will usually situate the egg sacs in the middle of the web, but if necessary, she will sometimes move them to a warmer or cooler spot. The eggs hatch fairly quickly, in approximately a week to ten days. The young spiders, or spiderlings, will stay in the sac until they molt once. After that, they will emerge from the sac and use their silk threads to catch an air current and disperse.

Female house spiders will molt seven times before reaching maturity, and the male will molt 6 or 7 times. After the young spiders reach maturity, they typically live for a year or more.

These spiders create webs in protected areas, sometimes high off the ground. Indoors, they are found in upper corners and ceilings, in window frames, and in higher humidity areas like crawl spaces and basements. Outdoors, they build webs under eaves, around windows, and near light fixtures that attract their prey. Their likelihood of survival is greatest outdoors in protected areas and least likely in low-humidity areas where prey is scarce.

Often times, house spiders will abandon one web and create another, giving the appearance of a more widespread spider population. House spiders can be beneficial because they eliminate other types of pests, such as mosquitoes or flies.