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Myths about "Dangerous" Spiders

Myth: Tarantulas are dangerous or deadly to humans.

Female European Tarantula (a wolf spider) in burrow Female Pink Toe Tarantula from above
European tarantula
Lycosa tarantula
Southern Europe; body length 2-3 cm
  (photo: Manuel J. Cabrero)
Click image to enlarge
Pink toe tarantula
Avicularia avicularia
Brazil to Trinidad; body length 6-7 cm
   (photo by Ron Taylor)
Click image to enlarge
Both the European wolf spiders (left) originally called tarantulas, and the theraphosid spiders (right), often kept as pets and called tarantulas now, have been reputed dangerous to humans. They aren't.

Fact: Outside of southern Europe (where the name is used for a wolf spider, famous in medieval superstition as the alleged cause of "tarantella" dancing), the word tarantula is most often used for the very large, furry spiders of the family Theraphosidae.

Hollywood is squarely to blame for these spiders' toxic-to-humans reputation. Tarantulas are large, photogenic and most are easily handled, and therefore they have been very widely used in horror and action-adventure movies. When some "venomous" creature is needed to menace James Bond or Indiana Jones, to invade a small town in enormous numbers, or to grow to gigantic size and prowl the Arizona desert for human prey, the special-effects team calls out the tarantulas!

In reality, the venom of these largest-of-all-spiders generally has very low toxicity to humans. I myself was once bitten by a Texan species and hardly even felt it. None of the North American species or those commonly kept as pets are considered to pose even a mild bite hazard. There have now been a few credible reports of moderate illness from the bites of a few exotic species that are definitely not standard pet store material. However, other people bitten by these same species reported no more than an initial "ouch" and perhaps a little muscle cramping.

The only health hazard posed by keeping pet tarantulas comes from the irritating hairs of the abdomen (in New World species), which can cause skin rashes or inflammation of eyes and nasal passages. To prevent such problems, simply keep tarantulas away from your face and wash your hands after handling one.

Compared to common pets such as dogs, tarantulas are not dangerous at all. (For more information see the American Tarantula Society).

Myth: Some spiders are deadly.

Fact: There is no spider species anywhere that can properly be called "deadly." Obviously, a few people have died from spider venom, but I know of no species anywhere on earth capable of causing death in humans in as much as 10% of cases, even if untreated. If the person bitten obtains medical aid, death from genuine spider bite ("mystery bites" falsely blamed on spiders don't count) is almost unknown in North America and a decided rarity worldwide. See the next section for a more detailed account of Australian and Brazilian spiders. "Deadly" spiders that can incapacitate you in minutes? Only in the movies!



Disclaimer: Information on this web site is not a substitute for professional medical advice, and should not be used to diagnose or treat a medical or health condition. You should consult a physician as to any symptoms that may require diagnosis or treatment. Genuine spider bites can sometimes require medical attention, but beyond that, several medical conditions commonly mistaken for spider bite can be even more serious. If you have what appears to be a serious spider bite, please contact your health care provider or local emergency services. If you have the actual spider that bit someone, always save it for identification by a professional arachnologist.

Text © 2003-2008, Burke Museum of Natural History & Culture,
University of Washington, Box 353010, Seattle, WA 98195, USA
Phone: 206-543-5590
Photos © as credited
Queries to Spider Myths author, Rod Crawford

This page last updated 2 September, 2010

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