9 Poisonous Types of Spiders You Should Know

Poisonous Types of Spiders
Photo by Ben_Kerckx

Spiders are creepy crawlers found anywhere, from deserts to jungles and even homes. There are over 20,000 species of spiders worldwide, and they come in all shapes and sizes.

Though they all look scary, not all are poisonous. Some are harmless, some bite, and some even kill their prey.

While most spiders are perfectly safe, there are several poisonous ones out there that can cause severe harm or death. Keep reading, as we have highlighted the poisonous types of spiders in this post.

Spiders are fascinating creatures, and there are plenty of myths surrounding them. Learn about these venomous arachnids, from the deadly black widow to the tarantula hawk.

1. Brown Recluse Spider

The brown recluse spider is one of the most common and poisonous types of spiders. We can find them across the United States, including New York City, where they live in woodpiles and trash cans.

The brown recluse spider is native to North America and is throughout much of the continent. It is a member of the genus Loxosceles, including the black widow and hairy desert scorpion species.

Also, it’s active during the day, light attracts them, and its bites cause painful lacerations that take weeks to heal.

Its exoskeleton ranges from light tan to dark reddish brown, and people often confuse it with black widows, but there are some key differences.

Black widows tend to live in areas where people spend a lot of time indoors, whereas brown recluse spiders prefer living outdoors. They are also larger than black widows, measuring 2–4 inches long.

While brown recluse spiders are harmless to humans, they threaten pets and livestock. When bitten, the spider injects a toxin called alpha-latrotoxin into the bloodstream of its victims. This toxin causes severe pain within minutes of being injected.

If a brown recluse spider bites someone, they must seek medical attention immediately. A person allergic to insect bites might develop a rash around the bite area. However, the risk of developing severe symptoms is low.

2. Black Widow Spider

Black widows are among the world’s deadliest spider species and are famous for killing people. Their venom contains neurotoxins that cause paralysis within minutes of being injected.

So, most victims die within 24 hours because respiratory failure occurs due to a lack of oxygen. There are over 20 different types of black widow spiders, and each one varies slightly from the next.

All black widows are small, ranging from 2 to 4 inches long. Also, their bodies contain venom that causes severe pain and swelling.

This venom contains an alpha toxin, which affects nerve endings, causing intense burning pain. Some people describe the feeling as similar to being burned alive.

There are no known cases of death caused by black widow spider bites, but several documented instances of paralysis exist. In addition, some victims experience respiratory distress.

Symptoms include vomiting, diarrhea, abdominal cramps, weakness, dizziness, headaches, fever, chills, muscle aches, nausea, and seizures.

Young children and older adults are especially vulnerable to severe effects. In rare cases, death may follow several weeks later.

3. Brazilian Wandering Spider

The Brazilian Wandering Spider is another spider among the poisonous types of spiders worldwide. This large brown spider is similar to Wolf Spiders but larger and possesses a more potent neurotoxin.

Brazilian Wandering Spiders are nocturnal hunters and travel widely throughout Brazil. They prefer warm climates and often hide in places like under rocks, logs, and inside houses during the day. When disturbed, they usually retreat quickly into nearby vegetation.

However, if provoked, they may attack, biting people who touch them. Most bites occur while the victim is sleeping, and the bite is almost always painless.

Although some bites produce severe symptoms, most do not. Many victims don’t even realize they’ve been bitten.

If you’re ever stung by a wandering spider, wash the area thoroughly with soap and water immediately. Seek medical help if you notice swelling around the bite site, fever, nausea, vomiting, difficulty breathing, chest pains, or heart palpitations.

4. Brown Widow Spider

The brown widow evolved in Africa, but the earliest known specimen came from South America. It’s an invader elsewhere in the world, and populations have appeared in Southern California, the Caribbean, along the coast of the United States, as well as in New Zealand and Japan.

The species has a brownish appearance ranging from tannish to almost black, but some have ornate dark brown, black, white, or orange markings on their abdomens.

The spiders make homes in buildings, inside old car tires, beneath vehicles, and among plants and shrubbery. Also, we can find them near areas of human activity, such as roadsides, parks, gardens, and warehouses. 

A typical female brown widow spider measures about one inch long, while males are smaller. Their bodies have fine hairs that help protect against water loss, and they live in groups called colonies, where there are usually tens of thousands of individuals. Most females are solitary; however, some do build webs.

5. Yellow Sac Spider

The yellow sac spider is also among the poisonous types of spiders. It belongs to the genus Cheiracanthium and is native to North America.

Its scientific name translates into “inclusive stone,” referring to the fact that it builds a web under stones, and logs, rather than in vegetation.

This little arachnid is about 2 inches long, is commonly outdoors, and lives in colonies where males and females occupy separate burrows.

Females lay eggs in a white sac attached to twigs and branches, and these sacs usually contain anywhere from 20 to 200 eggs. When the eggs hatch, the juvenile spiders emerge and disperse.

These spiders are harmless to people and pets, or the effects are usually minor. However, they threaten livestock because they prey upon insects, including flies, beetles, mites, and ticks.

Most bites affect children less than adults and do not cause severe symptoms. The most commonly reported effect is local itching.

However, there have been reports of mild systemic reactions, including fever, headache, nausea, vomiting, abdominal pain, dizziness, lightheadedness, and weakness.

6. Funnel-Web Spider

The funnel-web spider is one of the largest Australian spiders and also one of the most poisonous types of spiders. They build a silken web up to 2 m across, about 30 cm deep, and their body length ranges from 10–20 mm.

The name “funnel-webs” refers to the fact that the abdomen of the female contains a long, tubular silk cocoon in which she lays her eggs.

These spiders live throughout temperate regions of the world, including Africa, Asia, Australasia, Europe, and North America. In addition to being known for their neurotoxic venom, some species are notable for their vast size.

These spiders live in caves, under logs, rocks, and bark, and hunt mainly nocturnal insects such as cockroaches, beetles, grasshoppers, crickets, and ants.

Further, their venom contains neurotoxins called α-bungarotoxin and β- bungarotoxin, which block acetylcholine receptors. These cause paralysis and death within minutes.

7. Wolf Spider

The wolf spider belongs to the family Lycosidae, a large and widespread family of arachnids. There are around 40 genera and over 400 described species. Of those, approximately 125 occur in North America, while there are about 50 in European countries.

Its name derives from the resemblance of its face to a wolf’s snout. In addition, numerous species occur north of the polar circle, and most are small to medium-sized.

The name “wolf spider” refers to their hunting behavior; they chase down their prey and jump onto it from above. Also, it’s worth noting that members of this family are characterized by having eight eyes arranged around the periphery of the head.

These include four pairs of median ocelli, paired lateral eyes, and six pairs of posterior median eyes.

8. Six-Eyed Sand Spider

The Six-Eyed Sand Spiders are medium-sized spiders classified among the most poisonous types of spiders worldwide. They are cousins to the Recluses, which are found worldwide, and they live in dunes and similar habitats throughout much of sub-Saharan Africa. 

Due to their flattened stance, people sometimes call these dangerous spiders “Six-Eyed Crabs.” This spider bites people rarely but is deadly to rabbits within five to twelve hours.

9. Redback Spider

The Redback spider is a famous Australian spider belonging to the genus Latrodectus. They are famous for their distinctive red stripes on their backs, and the species name “hasseltii” refers to German entomologist Johann Georg Christian Lehmann, who described the species in 1817.

While the redback spider is not entirely dangerous to humans, it does pose a threat to pets. Its bite causes severe pain and swelling, followed by intense itching, nausea, vomiting, and muscle cramps.

In rare cases, pets bitten by redbacks have experienced respiratory failure, seizures, paralysis, and even death.

Also, the redback spider bites can transmit diseases like Lyme disease, encephalitis, and ehrlichiosis to humans.

Although it is not widely distributed outside of Australia, the redback spider has become established in some regions of California. Researchers believe the spider arrived in California during the 1990s via imported grapes.

In addition to their red markings, we can easily distinguish redback from other spiders by their long legs and large eyes near the front end of their bodies. Lastly, their venom is less toxic than that of some other spiders.

10. Red Widow Spider

The red widow spider is the last poisonous type of spider on our list. This species is very similar in appearance to the brown widow Latrodectus hesperus. However, it lacks distinctive markings on the underbelly of the abdomen.

Also, the red widow is smaller than L. hesperus, with females measuring approximately 1.5 to 2 inches long, compared to 3 to 4 inches for L. hesperus.

This venomous spider is aggressive behavior toward humans, and we can find it near human habitations because it feeds on insects attracted to light.

Moreover, its potent neurotoxic venom contains both α-latrotoxin and β-latrotoxin. These toxins are responsible for the symptoms associated with envenomation.

Although the bite of a red widow spider rarely causes death, severe effects include pain, muscle weakness, nausea, vomiting, abdominal cramps, diarrhea, and dizziness. In rare cases, victims experience cardiac arrest and even respiratory failure.


Spiders are fascinating creatures, and although they may be scary at first glance, some are pretty harmless. With this knowledge of some poisonous types of spiders, we should know the ones to avoid!

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