Dangerous Brown Recluse Spiders Found In Michigan, Oddly Enough

A Flint, Michigan, area family found a pair of unwelcome guests — quarter-sized brown recluse spiders — living in their unheated garage last week, and they and entomologists are at a loss to explain not only how they got there, but also how they survived the winter. The spiders, known for their dangerous venomous bites, are generally found in southern states with warmer climates.

The family spotted the long-legged arachnids on the unheated floor, captured them and contacted Howard Russell, an entomologist at Michigan State University Diagnostic Services, who confirmed the spiders were brown recluses.

Brown recluse spiders typically bite only when they are threatened, but the bites can cause serious wounds. They’re typically painless, and many people who are bitten don’t even realize it until several hours later when redness, swelling and tenderness occur near the bite area. Most brown recluse spider bites heal within a few weeks, but people who are particularly sensitive may have symptoms that persist for several months and leave deep scars.

Russell has been identifying and studying spiders for 30 years, and he’s flummoxed by the appearance of brown recluse spiders in Michigan. They’re typically found in southern states with warmer climates.

Russell told CBS News that out of thousands of species of arachnids submitted to him for review, only eight turned out to be brown recluse spiders. “So they’re rare,” he said, adding their appearance in Michigan raises an “interesting question research-wise.”

“Do these represent sort of a transported population or does this represent the leading edge of a spread of these things to the Midwest?” he wonders.

Brown recluse spiders aren’t entirely unheard of in Michigan, but in the cases where they have been confirmed, they likely hitchhiked in some sort of packaging. In the recent discovery, there was no travel involved.

Isolated populations of brown recluse spiders were discovered in Michigan in 2011 in the Lansing, Hillsdale and Flint areas.

In 2015, a population discovered in Tecumseh likely arrived with new kitchen cabinets that had been installed in the home before a family of five moved in, according to a Michigan State University Extension report.

The species was found in Ann Arbor in 2016. According to the report, “the Ann Arbor specimen came from a building on the University of Michigan campus.”

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Russell says Michiganders shouldn’t worry too much. There are far more dangerous spiders in the state, including Northern Black Widow Spider, which he said is “probably as dangerous or more dangerous than recluse spiders.”

But the likelihood of being bitten by one is slim. They’re shy, according to MSU Extension, and they’d rather scramble away than bite.

“That’s a good thing because the venom of a widow spider is 15 times more toxic than that of rattlesnakes,” MSU Extension says. “However, due to the small amount of the venom injected into the bite, widow bites are far less serious.”

Photo by Mike Keeling via Flickr Commons