From the Smokies: Wait — Don’t Kill That Spider! How Spiders Protect Us and Our Ecosystems

From the Smokies: Wait — Don’t Kill That Spider!

Though the word "spider" often prompts a reflexive "ew," these much-maligned arachnids perform vital services for people and ecosystems by keeping herbivorous insects—and the diseases they can carry—in check.

New discoveries in the Smokies

Researchers working in and around Great Smoky Mountains National Park have recorded 553 spider species there, including several recently described by scientists. In 2023, Marshal Hedin and Marc Milne published a 130-page study of the Appalachian genus Nesticus, revealing ten species new to science; three of these live in the Smokies and were named to honor Wilma Dykeman (Nesticus dykemanae), arachnologist Dr. Greta Binford (Nesticus binfordae), and the Cherokee people (Nesticus cherokeensis).

Why spiders matter

Spiders are arthropods—small, often hidden animals that "run the world," as arachnologist Kefyn Catley describes them. Arthropods (insects, crustaceans, springtails, millipedes, centipedes and arachnids) make up more than half of the species recorded in the park and provide life-support functions essential to terrestrial ecosystems. Scientists estimate that without arthropod-driven ecosystem services, most life on land could collapse within months.

As predators, spiders play a central role in regulating herbivorous insect populations. For example, spiders across roughly two acres of Western North Carolina forest can consume about 48 metric tons (105,840 pounds) of insects each year. Globally, spiders are estimated to consume 400–800 million metric tons of insects annually—many of which would otherwise damage crops or spread disease.

What makes spiders so successful?

Spiders have existed for approximately 400 million years and possess two notable innovations: silk and venom. Silk, produced through spinnerets at the tip of the abdomen, is used for webs, shelter and egg sacs; it also inspires biomaterials research and biomedical applications. Venom—delivered via bites and not to be confused with poison, which is ingested—paralyzes prey and begins digestion. Catley notes that less than 1% of spider species are hazardous to humans, and most species are shy and avoid contact with people.

"Without spiders we would probably succumb to some nasty insect-borne disease while waiting to starve to death," — Kefyn Catley

Risk perspective

Danger from spiders is often overstated. In the United States between 1979 and 1991 there were 1,135 deaths from lightning strikes and 57 deaths attributed to alleged spider bites—though experts believe up to 80% of those spider-bite claims were misdiagnoses. For perspective, during that period a person was roughly 20 times more likely to die from lightning than from a spider.

Within the park, the brown recluse is not native (though it occurs elsewhere in the region); the only spider native to the park that very rarely harms people is the black widow, which—like most spiders—is reclusive.

Practical benefits and what you can do

Beyond natural pest control, spiders are valuable model organisms for research in ecology, biochemistry, behavior, venom chemistry and biomaterials science. Spider silk is already used in some biomedical contexts and inspires new technologies.

Many spiders live indoors year-round—cellar spiders and parson spiders, for example—and provide continuous pest suppression. If you prefer not to kill spiders, a humane approach is simple: capture it with a cup and a stiff piece of paper or a postcard and release it outside, or—if it’s not bothering you—leave it be.

Credits

This article is adapted from a "Word from the Smokies" column originally published in the Asheville Citizen-Times. Frances Figart is the creative services director for Smokies Life. For more information visit SmokiesLife.org or contact frances@smokieslife.org.