Brazilian Wandering Spider: How to Identify and Avoid

The Brazilian wandering spider is one of the world’s most feared and aggressive spiders. Disturb one, and it instantly will rear up on its back legs and attack. Even an accidental encounter can result in a potentially fatal bite.

Whether or not the Brazilian wandering spider is the deadliest in the world is debatable. What isn’t is the fact that this spider does not like to run away from a fight. And lately, this spider keeps showing up in bananas bought by U.K. shoppers.

So, just in case you live in Brazil or just saw a giant spider crawl out of your fruit bowl while watching BBC news, here’s how to identify and avoid a Brazilian wandering spider.

Related: Is that a black widow spider?

Related: Meet the scary Huntsman spider.

Brazilian wandering spider
Brazilian wandering spider (family Ctenidae, genus Phoneutria) eating a cockroach in the nature. Photo credit: Ara.

Brazilian wandering spider: Description.

The Brazilian wandering spider (often called the banana or armed spider) is a member of Phoneutria genus of spiders from the family Ctenidae. Primarily found in South America and Central America, they frequently survive within fruit shipments to emerge in non-native regions.

Brazilian wandering spiders can have leg spans over 7 inches and bodies as long as 2 inches. Usually gray and brown, with a few species having light-colored spots on the abdomens, most have distinctive yellow and black or white ventral bands on the bottom of their two front legs.

The Brazilian wandering spider is most easily identifiable for its classic defensive posture. It’s the habit of rearing up on its back legs and displaying the colored ventral bands on its two front legs. Once in this position, the Brazilian wandering spider sways from side to side (like a knife fighter) with both hind legs cocked and ready to strike.

Related: Meet the adorable and harmless Jumping spider.

Brazilian wandering spider: Behavior and diet.

The Brazilian wandering spider isn’t lost; it just doesn’t maintain a regular nest or web of its own. Instead, it “wanders,” or hunts and patrols the jungle floor of Brazil at night and spends the heat of the day under logs, rocks, and tucked into banana plants. 

The species Phoneutria nigriventer, which mates from April to June, is known to hide in the darker, moisture reaches just outside or even inside human residences.

Brazilian wandering spiders eat tree frogs, small lizards, mice, and larger insects. However, they do not eat bananas.

The defensive display is just that, a display. We have the mistaken notion that there are only two options when attacked in the natural world—fight or flight. The Brazilian wandering spider offers you a third option—posture (so do chimps, apes, and others, by the way). 

Posturing means making yourself appear as large and dangerous as possible, thus making your attacker reconsider the profit vs. a loss of continuing to disturb you.

When the Brazilian wandering spider rears back, it exposes the reddish hair around its fangs and sends a clear warning—“I won’t back down or be taken without a fight.”

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Brazilian wandering spider
Brazilian wandering spider – Phoneutria boliviensis species of a medically important spider in family Ctenidae, found in Central and South America, dry and humid tropical forests. Photo credit: Pelanek

The dangers of being bitten by a Brazilian wandering spider.

It is the “wandering” nature of the Brazilian wandering spider that makes it so dangerous to humans.
Most venomous spiders strictly use their venom to kill prey. Venom is a limited (if replenishable) resource needed for food consumption.

Spiders have adapted their defensive bites to drive off an attacker using injury and pain while conserving their venom for later use on smaller prey.

Therefore, most defensive bites delivered to large mammals (like humans) are considered to be “dry” and do not contain venom.

The Brazilian wandering spider’s habit of seeking shelter during the day under logs and blankets, in boots and inside clothing, or amongst banana plants often leads to accidental envenomation of humans. It is these venomous bites that dangerous to humans.

Related: How long do ants live?

Related: What do ants eat?

The effects of the venom of Brazilian wandering spiders.

The effects of a venomous note from a Brazilian wandering spider on a human include:

  • Severe radiating pain that quickly spreads throughout the effected limb.
  • Tacycardia.
  • Fever.
  • Visual hallucinations.
  • Increased blood pressure.
  • Vertigo.
  • Sweating.
  • Nausea.
  • Vomiting.
  • Paralysis.
  • Breathing difficulties.
  • Death by respiratory failure.

Most symptoms onset within 30 minutes of the bite and death for those untreated by anti venom can occur within 2-6 hours.

Noted without comment, some human male’s suffer long painful erections as a result of being bitten by Brazilian wandering spiders. So, of course, the venom is being studied as a treatment for erectile dysfunction.

Related: Tarantula bites.

Related: Tarantulas: Appearance, diet, and mating.

When is anti venom used in Brazil for Brazilian wandering spider bites?

According to this case report, “Systemic envenomation caused by the wandering spider Phoneutria nigriventer, with quantification of circulating venom.”

“Antivenom has been used to treat envenoming by Phoneutria spp. in Brazil since 1925.

Current guidelines of the Brazilian Ministry of Health recommend that antivenom be given only to patients who develop important systemic clinical manifestations such as severe arterial hypertension, diaphoresis, convulsions, priapism, pulmonary edema, and shock; these manifestations occur in less than 3.3% of cases, including children.

The clinical state of our patient improved rapidly following antivenom administration (within 1–2 h after infusion), in agreement with the outcome of early cases.”

Brazilian wander spider: Mating and reproduction.

While the female Brazilian wandering spider is larger than the male (as in all spider species), she is much pickier in selecting a mate. Indeed, even the males have a more challenging time getting access to her, usually fighting off rivals before getting her attention.

Pity the poor male Brazilian wandering spider. He has to engage in leg-to-leg combat, perform a flawless and attractive dance, and then avoid (due to the male’s much smaller size), end up being a post-coitous meal.

If the male is accepted, the female will store up his sperm until she is ready to fertilize them. Then, she will lay hundreds of eggs and safely store them in a woven silk sac until they hatch. The emerging Brazilian wandering spiders will live for between 1-2 years.

Brazilian wandering spiders: Taxonomy.

As of March 2021, the World Spider Catalog accepted the following species:[1]

  • Phoneutria bahiensis Simó & Brescovit, 2001 – Brazil
  • Phoneutria boliviensis (F. O. Pickard-Cambridge, 1897) – Central, South America
  • Phoneutria depilata (Strand, 1909) – Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Ecuador
  • Phoneutria eickstedtae Martins & Bertani, 2007 – Brazil
  • Phoneutria fera Perty, 1833 (type) – Colombia, Ecuador, Peru, Brazil, Suriname, Guyana
  • Phoneutria keyserlingi (F. O. Pickard-Cambridge, 1897) – Brazil
  • Phoneutria nigriventer (Keyserling, 1891) – Brazil, Uruguay, Paraguay, Argentina
  • Phoneutria pertyi (F. O. Pickard-Cambridge, 1897) – Brazil
  • Phoneutria reidyi (F. O. Pickard-Cambridge, 1897) – Colombia, Venezuela, Peru, Brazil, Guyana

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Dennis V. Gilmore Jr.

Dennis V. Gilmore Jr. is a former Marine Sergeant and the author of several books, including two on night hunting coyotes and red and gray fox. He has written several hundred articles on predator hunting for

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