Meet the Most Dangerous Spider in the United States

by Taylor Cunningham
(Photo by Rob Stothard/Getty Images)

Meet the brown recluse, the most dangerous spider in the United States with venom capable of rotting human flesh.

We have the lowdown on the terrifying arachnid in time for Halloween just in case the slasher movie marathons aren’t scary enough.

Brown recluse spiders are plentiful in 16 states, including Alabama, Arkansas, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, Ohio, Oklahoma, Tennessee, and Texas. People can identify one by its chocolate brown color and three pairs of eyes. The spider also has violin-shaped marking on their backs.

Luckily, brown recluse spiders don’t like to live around humans—hence their name. Instead, they prefer to take shelter under rocks or boards. They also enjoy making homes out of bark or logs. However, though they don’t make themselves known like wolf spiders, they will live in houses. The creatures can often be found lurking inside cracks in walls and boards or behind or under stationary objects.

Because the arachnid prefers to live a life of solitude, bites are thankfully quite rare. When they do happen, it’s usually when someone accidentally comes in contact with them. That often occurs at night when the spider comes out of its hole and a peacefully sleeping person rolls on one. The second the venom hits the flesh, serious medical issues can arise.

The Brown Recluse Spider Carries a Necrosis-Causing Venom

The venom typically damages local tissues and then gives a variety of painful symptoms. Though, some people are lucky and have no symptoms at all.

“Brown recluse bite reactions may vary from no reaction at all, to a mild red wound, to a terrifying rotting flesh wound,” Jerome Goddard, a professor of medical entomology at Mississippi State University’s Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, told Newsweek.

The actual bite doesn’t feel like anything more than a pinprick—if the victim feels it at all. After three to eight hours though, the site may become swollen and red. As more hours pass, the central area may become pale or blue. It won’t be red. A black scab can form around 24 hours later. Then, the flesh around the bite may start to decay.

Those who suffer the worst of the symptoms can take months to heal, and as a reminder of the terrible experience, they’ll be left with a sunken scar.

“Their bites can produce nasty, slow-to-heal lesions that leave unsightly scars,” Goddard added.

Their venom contains an enzyme called sphingomyelinase D, which causes necrosis, or death of tissue. Scientists aren’t sure how many bites lead to rotting or why some people are affected while others aren’t. But they assume that some victims have an immune response that protects them.

“Or like venomous snakes, perhaps brown recluse spiders may deliver ‘dry’ bites wherein they withhold or don’t inject much venom,” Goddard suggested.

The good news is that necrotic bites are not fatal, just unsightly and painful. And treatment varies by doctor. If you do find yourself with a bite, there is some evidence that shows immediately applying ice to wounds can lessen necrosis because the enzyme works better in higher temperatures.