# Brazilian wandering spider (Phoneutria nigriventer) > A large, ground‑active South American spider with medically significant venom; often found in leaf litter, houses and banana shipments. Source: https://insectscanner.com/species/brazilian-wandering-spider/ (updated 2026-10-10) ## Is it dangerous? **Venomous bite.** Phoneutria nigriventer has a neurotoxic venom that can produce severe symptoms in humans, including intense pain at the bite site, sweating, nausea, vomiting, elevated heart rate and blood pressure, breathing difficulties and, in reported cases, painful and prolonged erections (priapism). Children are at greater risk of severe effects. If bitten: keep the person calm and still, immobilize the bitten limb at heart level, clean the wound with soap and water, seek emergency medical care promptly. Antivenom is available in countries where these bites are treated routinely (for example Brazil). Do not attempt to cut or suck the wound. **Pets:** Bites can be dangerous to small pets (cats, small dogs). If a pet is bitten observe for weakness, vomiting, breathing difficulty, or severe pain and seek veterinary care immediately. ## Quick facts - Scientific name: Phoneutria nigriventer - Also called: Banana spider, Armadeira, Aranha-armadeira - Order: Araneae (Spiders) - Family: Ctenidae (Wandering spiders) - Size: 30-50 mm body length; legspan commonly 6-12 cm - Colours: Brown, Dark brown, Tan, Reddish-orange (ventral patch) - Habitat: Lowland and disturbed forests, plantations, gardens, leaf litter, inside buildings and stacked produce. - Range: Eastern and central South America — primarily Brazil, but also reported from neighboring areas such as Bolivia, Paraguay and northern Argentina. - Active: Primarily nocturnal; most active at night and during warm months. - Lifespan: Adults typically live around 1-2 years in the wild; exact lifespan varies with sex and local conditions. - Effect on plants: Harmless - Pest: no ## Overview Phoneutria nigriventer is a nocturnal, wandering ground spider native to parts of South America. Rather than building webs to trap prey it actively hunts insects, other spiders and small vertebrates on the forest floor and around human structures. It is notable because its venom is potent to humans and is a medically significant spider in countries where it occurs. These spiders are usually encountered at night and may enter houses, vehicles or stacked produce (notably banana shipments). They shelter in litter, under logs, in crevices and sometimes inside shoes, clothing or boxes. Encounters near homes increase where natural habitat overlaps with populated areas. ## How to identify it Adults are relatively large, with long legs and a robust cephalothorax and abdomen. Colour is generally brown to dark brown with lighter patterns on the abdomen and legs; the belly is dark (the name nigriventer means "black belly"), the undersides of the front legs show contrasting dark and pale bands, and the jaws (chelicerae) are covered in reddish hairs. Legs are long and spiny compared with many other spiders. Females are generally bulkier than males; males often have longer legs relative to body size. - Large, long-legged ground spider with robust body and spiny legs. - No web for catching prey — typically found wandering on the ground or sheltering in crevices, leaf litter, boxes or clothing. - Dark belly, banded undersides to the front legs and reddish hairs on the jaws; upper side brown with lighter markings. - When disturbed it may raise its front legs and adopt an alert posture; males slimmer and longer-legged than females. ## Lookalikes - **Other Phoneutria species** (Phoneutria spp.): Closely related wandering spiders with similar habits; distinguishing requires close examination of body markings and genitalia and is best done by a specialist. - **Cupiennius (banana spider)** (Cupiennius salei and relatives): Cupiennius are also large, ground/vegetation-active spiders often found in bananas; they are not considered medically significant and differ in leg spination and eye arrangement—expert comparison is needed. ## Life cycle - **Egg sac:** Females lay eggs in silk sacs and guard them. Development time depends on temperature and humidity. - **Spiderling (juvenile):** Spiderlings hatch from the sac and disperse; juveniles resemble small adults and go through several moults as they grow. - **Adult spider:** Sexually mature spiders hunt actively. Adults mate, and females produce one or more egg sacs during the breeding season. ## Diet and predators - Young eat: Small insects and arthropods; young spiders take appropriately sized prey they can overpower. - Adults eat: Insects, other spiders and occasionally small vertebrates such as frogs or lizards. - Predators of the young: Ground predators such as ants, larger spiders, insectivorous birds and small mammals. - Predators of adults: Birds, larger arthropod predators, some mammals, and parasitic wasps that target spiders are known predators. ## Effect on plants and gardens This species does not feed on plants and has no direct harmful effects on crops or gardens; it is a predator of insects and small animals. ## Where and when to find it Look at night on the ground, under logs and leaf litter, inside stacks of boxes, clothing, shoes, or in banana/produce shipments. Juveniles are found in similar sheltered spots but are smaller and harder to spot. - Best time: Warm months and at night; early evening to late night is when hunting activity is highest. - Tips: When photographing or observing, keep distance, use a zoom lens or long-handled tools to move objects, and wear gloves and closed shoes when checking stored items. ## Fun facts - Phoneutria nigriventer is one of the medically important spiders of South America and has been studied for the potent neurotoxins in its venom. - It is called a wandering spider because it does not build a capture web but actively hunts at night. - Encounters with people sometimes occur when spiders hide in clothing, shoes or boxes, which is why growers and workers check produce such as bananas. ## Frequently asked questions ### Do Brazilian wandering spiders bite? Yes — they will bite if provoked or handled. Bites can inject neurotoxic venom that may cause severe symptoms in humans, so medical attention is important. ### Are they aggressive toward people? They are defensive rather than unnecessarily aggressive. They may display or bite if trapped against skin, picked up, or disturbed in confined spaces. ### Why is one in my house? They seek shelter in clutter, boxes, clothing, shoes, leaf litter, and buildings near their habitat. Movement of produce and goods can also introduce them to houses. ### How can I get rid of them safely? Avoid handling. Reduce clutter, seal cracks and gaps, store shoes and clothing off the floor, check boxes or produce before bringing indoors and call pest control if you have recurring sightings. ### What should I do if bitten? Keep the person calm and still, immobilize the bitten area, clean the wound, and seek emergency medical care immediately. Do not cut or attempt to suck venom. Antivenom is used where available. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/53391), [Wikipedia](https://en.wikipedia.org/wiki/Phoneutria_nigriventer). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.