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U-M undergraduate library reopens after venomous spider scare

Three Mediterranean recluse spiders were discovered in building in January

A brown recluse spider.
A brown recluse spider. (Wikimedia Commons)

ANN ARBOR – University of Michigan’s Shapiro Undergraduate Library reopened on Tuesday morning after a two-day closure due to reports that venomous spiders were on the loose.

As it turns out, three Mediterranean recluse spiders were discovered in the library’s basement in late January but were never seen in the building’s public spaces after the school’s pest management team treated the area.

U-M Public Affairs spokeswoman Kim Broekhuizen called the situation a “misunderstanding.”

“Based on what we know now, it was a mistake to close the building,” she wrote A4 via email. “As the name implies, they are reclusive and bites are extremely rare. Recluse spiders usually stay in mechanical spaces, tunnels and other hideaways. We apologize for the inconvenience to the university community.”

One of the more amusing aspects of this story were the reactions on Twitter:

According to associate professor of Biological Sciences at U-M Dearborn, Anne Danielson-Francois, Ph.D., Mediterranean recluse spiders are even more reclusive than the feared brown recluse spider.

“They are cave-loving,” said Danielson-Francois. “What happens is, they find a basement, a boiler room, a steam room and then that’s where a population develops. They don’t really seem to leave that area -- they stay contained there.”

She said that Mediterranean recluse spiders have been discovered in 22 states, largely due to hitchhiking.

As for the brown recluse spider, she said she has never found one in the field in Southeast Michigan.

“The people who would be most at risk would be plumbers crawling through a crawl space with lots of these spiders,” said Danielson-Francois. “Your average person is just not going to encounter these spiders. People don’t need to panic.”

As for bites, which are rare, she said it’s unlikely that a recluse would envenomate you.

“It would be a dry bite with red swelling, two little bumps right next to each other,” she said. “Really nothing happens. They’re not aggressive. You’d literally have to sit on one to get it to bite you.”

If it were to inject venom into a human, one could suffer a case of necrosis that would eat away at the affected tissue, but it would only be potentially life threatening if the person had an allergic reaction to the bite.

According to Broekhuizen, U-M’s pest management team continues to monitor the situation at the library.


About the Author:

Meredith has worked for WDIV since August 2017 and was voted one of Washtenaw County's best journalists in 2019 by eCurrent's readers. She covers the community of Ann Arbor and has a Master's degree in International Broadcast Journalism from City University London, UK.