There are many candidates for the title of the world’s deadliest spider. One of the most important considerations in determining the deadliest, is who the spider is deadly to. Some spiders can efficiently poison even small mammals with their venom, and a few can make humans very ill as well. Typical listings for deadliest spider include the Brazilian Wandering Spider, which occasionally shows up in cluster of bananas in the US, the Funnel Web Spider, which lives in Australia, and the Brown Recluse.
Despite its bad reputation, the Black Widow is generally not considered the deadliest spider in the world, even though its bite can make you ill and does call for medical attention. It’s hard to identify harmless spiders that look like Black Widows unless one is a spider expert, or an arachnologist.
The Guinness Book of World Records considers the Brazilian wandering spider to be the world’s deadliest spider. This is based on the spider’s venom being able to kill a certain number of mice. For a human, a bite from a Brazilian spider, or any spider for that matter, is not likely to kill instantly. Only 7% of the cases of bites from the Brazilian Wandering Spider require antivenin. Additionally, of 7000 reported bites from the Brazilian wandering spider, only a few deaths have been recorded, less than 1% of those bitten.
The statement that the Funnel Web Spider is the deadliest spider also requires some consideration. While one child died within 15 minutes of having received a Funnel Web Spider bite, adult fatalities when the adult was not treated took two to three days to occur. Again, death rate for bites from these spiders are under 1%. Only about 10% of people who receive a bite from a Funnel Web Spider require antivenin, though all should see a doctor.
The Brown Recluse is yet another candidate for deadliest spider. It is said to cause a bite that results in skin necrosis, infection and possible amputation. It is also said to be frequently found in California, when in fact, only 10 specimens of Brown Recluse have ever been collected there. It is certainly possible that a Brown Recluse or two makes it to California via people moving from the Midwest, but California is not the spider’s natural habitat. Again, the Brown Recluse tends to be the victim of bad press, and though bites from the Brown Recluse do need medical care, they seldom result in people’s limbs being amputated, and they occur with much less frequency than is often purported.
People in the Pacific Northwest US who claim to have been bitten by a Brown Recluse may have suffered a bite from a Hobo Spider, which can cause bacterial deterioration of the skin. Even with the Hobo Spider, 50% of all bites are called dry bites because no venom is injected.
One urban legend that persists is that Daddy Long-legs are actually the deadliest spider in the world, but their mouths are too small to bite humans. There are several reasons why this myth has no value. First, Daddy Long-legs can refer to several species of spiders, and even the crane fly. Second, research on venom has not verified that spiders identified as Daddy Long-legs are particularly venomous.
What remains constant in all definitions of the world’s deadliest spider is that all spiders pose very little threat to humans. Among the vast number of spider species, very few are potentially harmful. No human is the natural prey of any spider, and bites are usually the result of an accidental meeting with a spider rather than the natural aggression of the spider. For the most part, even the deadliest spider, whichever receives the designation, remains a helpful rather than harmful part of the human environment. On the other hand, for an insect or small rodent, the designation of deadliest spider is worth noting.