10 Most Venomous Spiders in the World

Of more than 4000 genera and 46,700 spider species, we have made a selection of 10 most venomous spiders in the world.

Many spiders are not venomous, but those who are are nasty. Spider venoms consist of many different toxins, and it is assumed that over 10 million spider toxins may exist, but around 1480 of them have been researched. Some spiders, like black widows for example, have venoms that are as much as 15 times stronger than those of rattlesnakes! Apart from black widows and rattlesnakes who share the same habitat, you might also be interested which are the States with the Most Venomous Snakes in America.

Being feared and hated, these creatures are actually very helpful, because they keep control over insects they feed on. Science has also benefited from researching spider venoms and silk. Did you also know that spider silk is the strongest and most elastic natural fiber? That is why scientists try to make synthesized silk for making fibers that could be used for parachutes and bullet-proof vests. Nevertheless, many people choose these exotic animals as pets, knowing that they are potentially highly dangerous.

For the ranking of venom strength of spiders on our list, we have used LD50 values, just like for the Most Venomous Snakes in the World. But this time, finding LD50 values for spiders was a bit more difficult. One reason is that there is no consistent list of summarized researches on this subject, rather there is a few analysis of spider venoms concerning certain genera or species. Some of the information and data we have gotten from scientific articles on different species like Sicarius and Loxosceles, Missulena, but also from other places like Principles and Practice of Toxicology in Public Health, Unbridled Optimist, La Tela Nera and Brown Widow Spiders. Some of the data was somewhat disagreeing, but we have tried to make the best out of it.

Let’s just quickly go through what the LD50 value is and why we’ve used it here for venom ranking. LD50 stands for a lethal dose of venom that kills 50% of sample – mice in this case. And the criteria is – the lower LD50 value is, the stronger the venom is. That means that the most venomous spiders are not also the most deadly ones, and not all would inject enough venom when biting nor are all harmful to humans and many other animals. But nevertheless, this value is a good indicator for determining the most venomous spiders in the world.

There has been a rumor that a tiny spider called Daddy Long Legs is one of the most venomous spiders in the world, but that its fangs are too small to bite humans. To find out if this claim is true, take a look at some of the most venomous spiders in the world:

10. Redback spider (Latrodectus hasselti)

LD50 value: 0.9

Although being one of the most famous indigenous Australian venomous spiders, Redback spider is in the last place on our list because of relatively high (comparing to others here) LD50 values of their venom. These spiders are easily recognized by a red strip on their back. They are infamous because they are responsible for 2,000-10,000 spider bites in Australia annually.

9. Chinese bird spider (Haplopelma  schmidti)

LD50 value: 0.7

Chinese bird spiders are species of tarantulas found in southern parts of China and in Vietnam. This is a highly aggressive species, and also very dangerous being highly venomous. It is also a rather large spider, being up to 8 inches long.

8. Black widow (Latrodectus mactans)

LD50 value: 0.59

Black widow ranks 8th in our list of the 10 most venomous spiders in the world. This species of black widow spiders is native to North America, and very well known for its highly toxic venom. The infamous name that this spider carries comes from the myth that female devours male after mating, but that claim remains a myth, as researches have shown.

7. Brown recluse spider, violin spider, fiddleback spider (Loxosceles reclusa)

LD50 value: 0.48

These spiders are found mostly throughout the south-central US, but are spread in Canada also. They can sometimes be found living in colonies of several thousand specimens. Although these spiders are somewhat common and highly venomous, bites in humans are not fatal, and even less than 10% are considered to be the “serious category” of bites.

6. Brown widow (Latrodectus geometricus)

LD50 value: 0.43

Although black widows are more famous spiders, their cousins, brown widows, have stronger venom. They are probably less dangerous because they are smaller than black widows. They are usually found in warmer areas of the Northern American continent, especially in Florida and surroundings.

5. Brazilian brown spider, grey recluse spider (Loxosceles similis)

LD50 value: 0.32

This spider that ranks 5th on our list of most venomous spiders in the world is a cousin of the above-mentioned brown recluse, together with whom it is one of the most venomous spiders in the world, and also very dangerous, because bites of this spider are quite frequent in Brazil.

4. Brazilian wandering spider (Phoneutria)

LD50 value: 0.3

These are very infamous venomous spiders of Phoneutria genus. They are also sometimes referred to as banana spiders as they are often found in banana shipments. The Guinness Book of World Records proclaimed this spider to be the most venomous animal in 2007, but that is not quite the case as we can see. They are highly aggressive large spiders (being 4-5 inches), and that is why they are one of the most dangerous spiders also.

3. Red headed mouse spider (Missulena occatoria)

LD50 value: 0.25

We are continuing our list of most venomous spiders in the world with this indigenous spider species in southern Australia. It is easily recognized by the red glossy head, but which is only red in males. Females, on the other hand, are evenly colored in black and sometimes have red jaws. They are also slightly larger than males. Although their venom is highly toxic, bites are very rare, and this spider is not considered to be a dangerous one.

2. Sydney funnel web spider (Atrax robustus)

LD50 value: 0.16

This spider is native to Eastern Australia, and most common around Sydney area. Interestingly, males are more dangerous than females, which is very unusual in the world of spiders. Although often a very small portion of venom is injected in recorded bites in humans, it is known that when a larger dose is injected, only 15 minutes is enough to kill a human. It is also interesting that their venom is specifically dangerous to primates.

1. Six eyed sand spider (Sicarius hahni)

LD50 value: 0.004

What makes this weird-named six eyed sand spider the most venomous spider in the world is the fact that very tiny dose of its venom painfully kills its victim. It is indigenous to South African deserts where it camouflages very nicely. It is not fond of making webs, and instead hunts its pray, sometimes by burying in the sand where it can spend a lot of time, being able to live without food for months. Of two known cases of bites in humans, one ended in death and the other in amputation!