Spiders

Spiders are among the most feared household pests, but the vast majority of the 3,000+ species found in North America are completely harmless to humans — and many are actually beneficial, feeding on mosquitoes, flies, and other nuisance insects. Understanding which spiders are dangerous and which are helpful is key to making smart decisions about spider management in your home.

Only two spider species in the United States pose significant medical risks. The brown recluse (Loxosceles reclusa) is found primarily in the South-Central and Midwestern states (from Texas to Georgia, north to Iowa). It has a violin-shaped marking on its back, six eyes arranged in three pairs (most spiders have eight eyes), and uniform tan-to-brown coloring. Brown recluse bites can cause necrotic tissue damage that requires medical attention. The black widow (Latrodectus species) is found nationwide and is identifiable by its shiny black body with a red hourglass marking on the underside. Black widow venom is neurotoxic and can cause muscle pain, nausea, and difficulty breathing, though fatalities are extremely rare with modern medical treatment.

Common harmless house spiders include cellar spiders ("daddy long legs" with thin legs and small bodies), jumping spiders (compact, curious, excellent pest controllers), wolf spiders (large, brown, fast-moving ground hunters), and cobweb spiders (build messy webs in corners). These species are generally more beneficial than harmful.

An important principle of spider management is that a large spider population usually indicates a larger insect problem. Spiders go where the food is. If you are seeing many spiders indoors, it typically means there is a significant population of insects (ants, flies, moths, beetles) that is attracting and sustaining them. Addressing the underlying insect problem will naturally reduce spider numbers.

For homes in brown recluse or black widow territory, professional perimeter treatments using residual insecticides can create a barrier that reduces spider entry. Glue traps placed along baseboards and in closets are an effective monitoring tool and can help gauge the severity of a spider population.