Spiders that bite humans are generally not aggressive by nature. Most bites occur when the spider is disturbed or feels threatened. These incidents often happen accidentally, such as when a person reaches into dark corners, wears clothes left on the floor, or works outdoors among vegetation.
The venom of biting spiders varies widely. Some produce mild symptoms similar to a bee sting, while others can cause more serious effects such as tissue damage or systemic reactions. In most cases, the bite only results in localized pain, redness, and swelling.
Not all venomous spiders pose a danger to humans. In fact, most have fangs too small to penetrate human skin or venom too weak to cause significant harm. Severe reactions are rare and often depend on individual sensitivity or allergic response.
Some spiders are more commonly associated with medical attention. These tend to be species that dwell close to human environments, such as basements, sheds, or garages. Their bites may sometimes require first aid or even professional medical care, especially if symptoms worsen.
Despite their reputation, fatal spider bites are exceptionally rare. Prompt cleaning of the wound, applying ice, and monitoring symptoms is typically enough. In certain cases, antivenom or pain relief medication may be recommended.
It’s important to remember that most spiders serve valuable ecological roles, especially in pest control. Their presence in homes and gardens often goes unnoticed, and bites only occur in a small percentage of human-spider encounters.
Spiders That Bite Humans
Brown Recluse Spider (Loxosceles reclusa)
This spider is well-known for its necrotic venom, which can cause serious skin lesions in some individuals. It has a violin-shaped mark on its back and prefers undisturbed, dark areas such as basements, closets, and attics. Native to the central and southern United States, it rarely bites unless threatened.
Black Widow Spider (Latrodectus mactans)
Easily recognized by its shiny black body and red hourglass marking, this spider is found throughout North America in woodpiles, sheds, and dark corners. Its venom is neurotoxic and can cause muscle pain, cramps, and spasms, but bites are rarely fatal with medical care.
Yellow Sac Spider (Cheiracanthium inclusum)
Common in homes and gardens, especially in North America, this pale yellow to green spider hides in silken sacs during the day. Bites can cause mild to moderate irritation, redness, and sometimes blistering. It is often blamed for bites indoors.
Hobo Spider (Eratigena agrestis)
Native to Europe but now established in the Pacific Northwest, this spider builds funnel webs in cracks, basements, and sheds. Although its reputation as a harmful biter is debated, some cases have reported necrotic wounds similar to recluse bites.
Wolf Spider (Hogna spp.)
These large, hairy, fast-moving spiders are often found on the ground in grasslands, forests, and homes. While they are not aggressive, they may bite if handled. The bite is usually painful but not dangerous, causing swelling and redness.
Tarantula (Various Genera)
Though intimidating in size and appearance, tarantula bites are rarely serious. They are native to the Americas, especially the southwestern U.S. and Central and South America. A bite may cause localized pain similar to a bee sting, and some species can flick irritating hairs.
Brazilian Wandering Spider (Phoneutria spp.)
Among the most venomous spiders in the world, this aggressive hunter is found in tropical South and Central America. Its venom can cause serious symptoms, including muscle problems and breathing difficulty, but bites are rare due to limited human contact.
Redback Spider (Latrodectus hasselti)
Closely related to the black widow, this spider is found in Australia and parts of Southeast Asia. It has a black body with a prominent red stripe and delivers a venomous bite that can cause intense pain, sweating, and nausea.
Six-Eyed Sand Spider (Sicarius spp.)
Native to deserts of southern Africa, this spider is rarely encountered by humans, but its venom is potentially deadly, causing tissue destruction and bleeding. Its reclusive nature and excellent camouflage make bites extremely rare.
False Black Widow (Steatoda grossa)
Often mistaken for true black widows, this spider is found in Europe, North America, and Australia. Its bite may cause moderate symptoms such as pain, fever, and muscle cramps, but it is not considered dangerous.
Mouse Spider (Missulena spp.)
Native to Australia, these ground-dwelling spiders have powerful fangs and can deliver venomous bites. Some species have venom similar to that of funnel-web spiders, but bites are rare, and effective antivenom exists.
Australian Funnel-Web Spider (Atrax robustus)
Found in eastern Australia, especially near Sydney, this spider is one of the most venomous to humans. It lives in moist burrows and may be aggressive when threatened. Its bite can be fatal without antivenom, though fatalities are now extremely rare due to effective treatment.
Desert Recluse (Loxosceles deserta)
Closely related to the brown recluse, this spider inhabits arid regions of the southwestern United States. It prefers dry, undisturbed environments such as under rocks or debris. Its venom is necrotic and can cause ulcerating sores, though bites are rare due to its reclusive behavior.
Mediterranean Recluse (Loxosceles rufescens)
Originally from the Mediterranean region, this spider has spread to parts of the U.S., Asia, and South America. It has similar venom effects to other recluse spiders, causing skin necrosis in some individuals. It often hides in cracks, basements, and other sheltered spots.
Brown Widow (Latrodectus geometricus)
A relative of the black widow, the brown widow has a mottled tan to dark brown body and an orange or yellowish hourglass on its underside. It is less aggressive and its venom is less potent, but bites can still cause pain, redness, and muscle stiffness. It is found in warm climates around the world, especially in Florida, California, and tropical regions.
Katipo Spider (Latrodectus katipo)
Native to New Zealand, the katipo is a venomous spider related to the widow species. It typically dwells in coastal sand dunes under driftwood or foliage. Although now rare, its bite can cause systemic symptoms, including sweating, muscle pain, and nausea.
Chilean Recluse (Loxosceles laeta)
Considered the most dangerous recluse spider, the Chilean recluse is found in South America and occasionally in North America due to accidental importation. Its venom is highly necrotic and can lead to severe tissue damage or systemic illness. It hides in dark, quiet areas like closets and furniture.
Armed Spider / Banana Spider (Phoneutria nigriventer)
A member of the Brazilian wandering spider genus, this species is among the most venomous spiders globally. It is aggressive when threatened and is known for occasionally hiding in banana shipments, which is how it gets its nickname. Found in South America, its bite can cause severe pain, drooling, high blood pressure, and, rarely, death without treatment.
Six-Eyed Sand Spider (Sicarius hahni)
Native to deserts of southern Africa, this spider is related to the recluse family. It buries itself under sand and remains motionless to ambush prey. Its venom contains potent cytotoxins that can cause extensive tissue destruction. Although bites to humans are extremely rare due to its remote habitat and non-aggressive behavior, they can be medically serious.
Yellow Sac Spider (Cheiracanthium inclusum)
Common in homes across the United States, especially in corners of walls and ceilings, this small pale spider is often encountered indoors. Though not dangerous, its bite can be painful, causing redness, swelling, and a burning sensation. Secondary infection may occur if left untreated, but complications are rare.
Wolf Spider (Hogna spp.)
Large and hairy, wolf spiders are often found in gardens, fields, and homes. They are fast runners and hunt prey rather than using webs. Their bite may cause localized pain, itching, and swelling, but their venom is not harmful to humans. These spiders will bite in self-defense if provoked or handled roughly.