Spiders of the United States

The brown recluse is one of two spider species in North America whose venom is established as capable of causing medically significant injury in humans. Its native range is tightly bounded - confirmed established populations occur in a band from southern Iowa through eastern Texas - and the species is frequently misidentified outside that range.

The southern black widow is the most familiar of the North American widow spiders, recognized by the glossy black female with a complete red hourglass on the underside of the abdomen. Bites are uncommon but medically significant; antivenom exists.

The western black widow occupies the arid western half of the continent and is the widow species responsible for the overwhelming majority of bites reported in California, Arizona, and the Mountain West.

An invasive widow that has rapidly displaced native black widows across the southern United States. The brown widow's venom is comparable in potency to the black widow's, but smaller venom yields produce milder envenomations.

Once listed by the CDC as a spider of medical concern, the hobo spider was formally removed from that list in 2017 after subsequent research failed to replicate the necrotic effects originally attributed to its bite.

A small pale spider commonly found indoors throughout North America. Although its bite is sometimes painful and was historically blamed for necrotic lesions, current evidence suggests true necrosis is rare.

A large, brightly colored orb weaver native to East Asia that was first documented in north Georgia in 2014. Joro spiders have since spread across much of the southeastern United States and are projected to continue expanding because of their unusual cold tolerance for a tropical-origin spider.

The northern black widow is the widow species of the northeastern United States and southeastern Canada. The female is distinguished from L. mactans by a broken (not continuous) red hourglass and a row of red spots running down the dorsal midline of the abdomen.

A Florida-endemic widow restricted to scrub-pine habitat in the central and southern peninsula. Distinct from other North American widows in coloration - orange-red cephalothorax and legs with a black abdomen marked by red spots, and no ventral hourglass.

The most frequently encountered indoor spider across temperate North America. Often confused with widow spiders because of its similar tangled cobweb and spherical abdomen, but its mottled brown coloration and small size distinguish it.

Wolf spiders are large, fast-moving ground-hunting spiders frequently mistaken for brown recluses because of their brown coloration. Unlike recluses, they have eight eyes in a distinctive three-row pattern, do not build prey-capture webs, and are not medically significant.

The long-bodied cellar spider is the source of the persistent 'most venomous spider in the world' myth. The claim is false: while the spider does bite humans, its venom is mild and has no documented medical significance. The species is also frequently confused with the harvestman (true daddy long-legs, Opiliones), which is not a spider at all.

The most commonly encountered jumping spider in North America. Recognized by its compact black body, iridescent green chelicerae, and three white or orange spots on the dorsal abdomen. Jumping spiders are diurnal active hunters with the sharpest vision of any arthropod and are not medically significant.

A large, conspicuous orb weaver of gardens and meadows across the Lower 48. Recognized by the female's bold black-and-yellow markings and the prominent zig-zag stabilimentum woven into the center of her web.

A large orb weaver of the southeastern United States, known for the golden tint of its silk and its very large, persistent webs. Frequently called 'banana spider' in the southeast - a common name that creates confusion with the unrelated and highly venomous Phoneutria of Central and South America.

Grass spiders are funnel-weaving agelenids that build sheet webs with a tubular retreat in lawns, ground cover, and along foundations. Frequently confused with wolf spiders and hobo spiders. They are not medically significant.

A large crevice-weaving spider common in the U.S. South. Males are large, leggy, and frequently mistaken for brown recluses; females are darker, robust, and stay hidden in crevices on the outsides of buildings.

A large funnel-weaving spider introduced to the Pacific Northwest from Europe. Closely related to the hobo spider and increasingly displacing it indoors. Conspicuous because of its size - leg span can exceed 100 mm - but not medically significant.

The most medically significant recluse worldwide. Native to South America and introduced to a few U.S. localities (notably Los Angeles County). Bites are responsible for the majority of confirmed loxoscelism worldwide and have a higher rate of systemic complications than L. reclusa.