A woman reportedly bitten by a brown recluse spider in Northern Michigan has become the latest in a handful of encounters with the poisonous spider in Michigan.
Entomologists have been uncertain about whether these sightings are spiders that have been transported north from their normal range, or if there are populations established in the state. However, an increase in documented brown recluse sightings suggest that small populations may have become established.
A lot of people who say they've seen a brown recluse in Michigan -- or been bitten by one -- are mistaken, according to Michigan State University entomologist Howard Russell.
He says he’s been collecting photos and specimens of suspected brown recluses and out of about 700 submissions, most have not been a brown recluse.
Although the brown recluse bite is known to generate an unusually severe reaction, in certain sensitive individuals, other spider bites can cause a similar reaction. So the presence of symptoms associated with a spider bite is not conclusive proof of the presence of a brown recluse.
“I've had cases where doctors, even at the U of M hospital, have diagnosed a bite as being a brown recluse bite, and the person actually had found the spider, and sent me the spider, and it was not a brown recluse,” says Russell.
However, Russell has confirmed enough of the sightings to expand the list of Michigan counties where they’ve been found. “We've had brown recluse, at least small isolated populations, confirmed in Genesee, Hillsdale, Ingham, Lenawee, Livingston, Oakland, Shiawassee, Washtenaw, and Wayne County,” says Russell. The brown recluse has also been confirmed in Kent County.
He says the brown recluse could survive milder Michigan winters, especially in sheltered areas like sheds and garages. They are normally temperature sensitive, and don’t range farther north than southern Ohio.
Russell is still collecting suspicious spiders and photos. Suspected brown recluse spiders can be sent to Dr. Russell at the MSU Extension.