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Although you might assume we've already covered the world's most dangerous spiders, Mytour has never compiled a list quite like this. While we've explored deadly snakes and other venomous creatures, venomous spiders have remained overlooked—until now.
Let's start by clearing up a common misunderstanding: spiders are generally venomous, not poisonous. For an organism to be poisonous, it must be harmful when ingested. Venomous creatures, on the other hand, cause harm by delivering venom, typically through their fangs. Now, let's dive into the list!
Globally, most people would agree that spiders are creatures they'd prefer to avoid. Arachnophobia, or the fear of spiders, is one of the most common phobias around the world, and it's not hard to see why.
Our fears don't come from nowhere; they’ve evolved as a survival mechanism in a dangerous world. Although most spiders are harmless to humans, a few species can deliver bites that are fatal, and it's these terrifying spiders that make arachnophobia a completely rational fear.
10. Wolf Spider—Hogna carolinensis
Part of the Lycosidae family, Wolf Spiders earn their name from their wolf-like behavior, hunting down and pouncing on prey. There are around 125 species in North America and 50 in Europe. Typically measuring about 2.5 cm (1 inch), with an additional 2.5 cm from their legs, they can appear black, gray, or brown. One of their most distinctive features is their eye arrangement: four small eyes at the bottom, two large ones in the middle, and two medium-sized eyes on top. These venomous spiders are often mistaken for brown recluses (due to their similar color) or tarantulas (due to their hairiness). Unlike many spiders, they don’t wait in webs to catch prey—they actively hunt and drag their catch back to their den, which they line with webbing to create a funnel-like structure.
Wolf spiders subdue their prey by injecting venom. While they’re not aggressive towards humans, they may bite if threatened. The bite typically causes a red, itchy welt as the body reacts to the venom. Some individuals, especially those with a sensitivity to spider bites, might experience nausea, rapid heart rate, dizziness, or even necrosis around the bite. In rare cases, a bite could be fatal, depending on the person's reaction, so immediate medical attention is advised if bitten.
9. Yellow Sac Spider—Cheiracanthium inclusum
Yellow Sac Spiders are commonly found and range in size from just 3 to 15 mm (0.1 to 0.67 inch). Although their small size might cause you to overlook them, the size of a spider doesn’t always matter when it comes to a bite. The venom of a Yellow Sac Spider contains a cytotoxin, a harmful substance that disrupts cellular functions and can cause cell death. If bitten, you'll immediately know, as their bites are extremely painful.
The good news is that a bite from a Yellow Sac Spider, while incredibly painful, is unlikely to be fatal. You may feel as if you'd prefer to die from the intense pain, but there have been no recorded deaths. These spiders fiercely protect their territory, so you definitely don’t want to threaten their egg sacs. The venom can cause localized necrosis, which can easily be mistaken for a Brown Recluse bite. Some species of Cheiracanthium are more severe than others, with C. inclusum and C. mildei being the most common.
8. Brown Recluse Spider—Loxosceles reclusa
The Brown Recluse Spider is one of the most feared spiders in the modern world due to the potency of its venom. While a bite from a Brown Recluse is unlikely to be deadly, it can cause significant tissue death because its venom is necrotic. Similar to a rattlesnake bite, the venom spreads through the veins at the site of the bite, leading to the destruction of the affected tissue. One of the issues with a Brown Recluse bite is that you might not feel it right away, and the pain may not be immediate. This delay can lead to the symptoms being misdiagnosed.
The extent of necrosis caused by a spider bite can vary, and not all bites result in tissue death. Only about 37% of bites lead to the death of skin tissue. A small number of individuals may experience hemolysis—the rupture of red blood cells. The fear of necrosis is what makes these spiders especially terrifying to humans, and they are commonly found throughout the central and southern United States. Despite their widespread presence, they are typically not aggressive. However, if left untreated, bites can cause large sections of skin to become gangrenous.
7. Redback Spider—Latrodectus hasseltii
The Redback Spider, often referred to as the Australian Black Widow, is frequently mistaken for a Black Widow due to its similar appearance and the distinctive red mark on the back of the female. This spider is highly venomous, possessing a mix of neurotoxins that can cause excruciating pain in humans. Fortunately, they typically do not inject their full venom load, reserving some for their prey. However, if a Redback Spider were to deliver all of its venom, the outcome could be fatal.
That said, no deaths have been reported from Redback Spider bites since the development of an antivenom in 1956. Before the antivenom was introduced, a bite could easily result in death, and it’s likely that this would still be the case without timely access to the antivenom. Symptoms of a bite include nausea, excessive sweating near the bite site, muscle weakness, and vomiting. These spiders aren’t shy and will bite if they feel threatened—just ask one unfortunate Australian man who encountered one while sitting on a toilet.
6. Brown Widow Spider—Latrodectus geometricus
The Brown Widow Spider is a particularly dangerous relative of the infamous Black Widow. These small but deadly creatures carry a potent neurotoxin in their venom, which can lead to a condition called Latrodectism, named after the spider itself. The venom of the Brown Widow is even more toxic than that of the Black Widow, but due to the spider's more cautious nature, it rarely delivers a full envenomation when it bites. These spiders are extremely timid and will only bite when they feel threatened or disturbed.
That said, getting bitten by a Brown Widow Spider is extremely painful. While no fatalities have been recorded from its bite, the pain has been compared to being struck by a sledgehammer. The venom causes instant pain and muscle spasms, and if left untreated in a sensitive area, it could lead to paralysis of the spine or brain. Their range has expanded globally, and they are now found throughout the developed world.
5. Six-Eyed Sand Spider—Sicarius hahni
The Six-Eyed Sand Spider is a cousin of the Recluse Spiders, but it's found exclusively in the deserts of southern Africa. Some consider it the most venomous spider in the world. These spiders excel at blending into their surroundings, thanks to tiny hairs known as setae, which collect sand particles and form a natural camouflage. This allows the spider to bury itself beneath the sand and wait patiently to ambush unsuspecting prey. Although they rarely attack humans, a bite from this spider could be deadly.
Most of the time, bites from these spiders don’t lead to envenomation, as they typically reserve their venom for prey. However, their venom contains cryotoxins that can cause severe tissue and organ damage. A fully envenomated bite would likely result in hemorrhaging, followed by liver and kidney failure. Death would soon follow, and unfortunately, there is no known antivenom. Thankfully, there are no documented cases of these spiders biting humans, but based on the potency of their venom, that’s certainly a relief.
4. Black Widow Spider—Latrodectus mactans
Black Widow Spiders are among the most infamous arachnids on Earth, their danger reinforced by their constant presence in popular culture. The term 'Black Widow' has come to describe women who kill their husbands, and Marvel Comics even named a deadly assassin after these little creatures. Found across North America, Central America, Africa, and the West Indies, there's a good chance one could be lurking nearby right now.
National Geographic ranks the Black Widow Spider as the most venomous spider in North America, with venom that is 15 times more potent than that of a rattlesnake. A bite from a Black Widow may only leave a small puncture wound, but don’t be fooled by the size of the mark—there’s a dangerous amount of venom coursing through your bloodstream. This can lead to severe muscle cramps, nausea, and diaphragm paralysis, which makes breathing difficult. While bites can be fatal for infants or the elderly, no recorded deaths from a Black Widow bite have occurred.
3. Brazilian Wandering Spider—Phoneutria fera
If bitten, death can occur in less than an hour if left untreated. Fortunately, Brazilian Wandering Spiders rarely inject venom into humans, preferring to reserve it for their actual prey. However, bites can cause strange side effects, such as tachycardia, nausea, blurred vision, hypothermia, and death. One especially odd reaction is that males may experience a painful erection that can last for hours. If the embarrassment doesn’t kill them, not treating the bite certainly will. So, if you ever find one of these spiders among your bananas, avoid it at all costs.
If bitten, death can occur in less than an hour if left untreated. Fortunately, they don’t often envenomize their bites with people, preferring to save it for their actual prey. There are some unusual side effects of Brazilian Wandering Spider bites aside from tachycardia, nausea, blurred vision, hypothermia, and death; males may experience a painful erection, which will last for hours. If the embarrassment doesn’t kill them, not treating the bite certainly will, so if you ever find one of these spiders lurking in some bananas, avoid it at all costs.
2. Sydney Funnel Web Spider – Atrax robustus
Australia, often associated with its massive and ferocious creatures, is also home to a spider that claims the title of the most hazardous in the entire continent. The Sydney Funnel Web Spider is acknowledged by Guinness World Records as the 'most venomous' spider when it comes to human toxicity. Though the precise lethal dose of venom remains undetermined, its potency in causing harm to the crab-eating macaque has been recorded as 0.2 milligrams per kilogram. Typically, a male Sydney Funnel Web Spider produces around 176 milligrams of venom per bite.
The venom of the Sydney Funnel Web Spider is especially dangerous to primates, including humans. The venom contains δ-atracotoxin, a neurotoxin that disrupts the nervous system. Unlike snakes, which release venom in small doses with each strike, these spiders are far more aggressive, injecting a full dose of venom with a single bite. Many fatalities were reported from these spiders before an antivenom was developed in 1991.
1. Chilean Recluse Spider – Loxosceles laeta
While Brown Recluse spiders are feared for their venom that causes tissue death, they are far less dangerous than their Chilean relatives. The Chilean Recluse Spider is regarded as the deadliest of all Recluse species, with bites that can lead to severe damage or even death. Fortunately, like other Recluse spiders, they are not typically aggressive towards humans and will only bite if provoked. Their venom contains a powerful dermonecrotic toxin that destroys the tissue around the bite. In more serious cases, this can result in life-threatening complications.
In approximately 4% of incidents, the venom leads to catastrophic consequences, including death. This occurs when the venom is in large quantities or when it targets critical areas like the heart or kidneys. Renal failure is the most frequent severe outcome of a fully envenomated bite, but such occurrences are extremely rare. Their venom is 15 times more lethal than certain cobra species and up to 10 times more powerful than sulfuric acid.
