5 of the Most Dangerous Animals in Wisconsin

Tom Giffey |

Brown Recluse Spider (Image: Lisa Zins, CC BY 2.0)

1. Brown Recluse Spider

The brown recluse – a one-third-inch-long spider with a violin-shaped marking near its head – recently made headlines for apparently biting some Chippewa Valley residents. While this bite can lead to swelling, pain, and even necrosis (tissue death), fortunately the species is rare in Wisconsin. It is one of only two venomous spiders in Wisconsin, the other being the northern black widow.

2. Rattlesnakes

Two species of rattlesnakes – the timber rattler and the eastern massasauga – are native to Wisconsin. Fortunately for you ophidiophobes, both critters are usually found only in southwestern Wisconsin and both are fairly rare: Massasaugas are actually an endangered species and Timber Rattlers are most frequently found playing minor league baseball in Appleton. And while they are venomous, they are rarely deadly: There’s been only one rattlesnake-related death in the state since 1900.

Massasauga Rattlesnake (Image: Tim Vicekrs)
Massasauga Rattlesnake (Image: Tim Vicekrs)

3. Ticks

When it comes to bites, you’re far more likely to be targeted by ticks than snakes. The worst is the tiny black-legged tick – a.k.a. the deer or bear tick – which often carries Lyme disease. About 40,000 cases of Lyme have been identified in Wisconsin since 1990. Ticks can carry other nasty infections, too, including babesiosis, ehrlichiosis, anaplasmosis, and spotted fever rickettsiosis. If you’re headed into the underbrush, spray down with DEET, wear long pants and sleeves, and check your bodily nooks and crannies for the critters.

4. Mosquitoes

Fun fact: More than 50 mosquito species call Wisconsin home! Unfun fact: Their females are looking for their next "blood meal," and it could be you! Besides their annoying bites, mosquitoes can carry West Nile virus and La Crosse encephalitis. In rare cases, both ailments can be deadly, which is all the more reason to generally avoid these bloodsuckers.

White-Tailed Deer (Image: USDA photo by Scott Bauer)
White-Tailed Deer (Image: USDA photo by Scott Bauer)

5. White-Tailed Deer

The white-tailed deer is actually one of Wisconsin’s deadliest animals. According to the Department of Transportation, there are at least 20,000 vehicle/deer crashes annually, 15 to 20 percent of which cause injury. In 2017 alone, nine people died as a result of these crashes.