When you picture dangerous pests, you probably think of a prehistoric moth the size of a sudan living in a distant misty jungle. You almost certainly don’t think “Michigan.” Nevertheless, there are several types of highly poisonous pests living in Michigan today. Some of them are even Michigan natives!

We’re not (just) freaking you out because it’s fun. Learning to identify Michigan’s biggest baddies is important, so you can learn how to stay safe from them. They may not be the bloodthirsty, terrorizing monsters you picture, but any of these four pests could ruin your day and then some.


black widow spider

Black Widow

The Northern black widow spider’s habitat ranges throughout the eastern and central US. Michigan’s trees and prey make it the ideal environment for the poisonous spider to thrive in. Northern black widows are inch-and-a-half long, black spiders with a red “hour glass” marking on the back of their abdomens. The spider is common around Michigan’s lower peninsula, especially in the Southwest.  

While it’s true that they are common in Michigan, widow bites are quite rare. Black widows are timid and only bite if their web is threatened. Widows build their webs anywhere they can catch prey. They’re most commonly found in dark, damp locations like old stumps, hollow logs, fence posts, sheds, crawlspaces, basements, and woodpiles. Symptoms of black widow bites appear after 30 to 60 minutes and include muscle spasms, chills, nausea, fever, sweating, aches and pain, and headaches. If you’re bitten by a black widow, seek medical help immediately.


brown recluse spider

Brown Recluse Spider

The brown recluse is a poisonous spider native to the Southeast US. Experts traditionally believed that Michigan winters keep brown recluses out. However, from 2011 to 2017, six populations of brown recluse spiders have been identified in Michigan. The most recent population in Davison, Genesee County, lived in an unheated, detached garage. The fact that they lived through the winter in an unheated environment may imply that they can establish themselves in Michigan permanently.   

Recluses are around 6 to 20 millimeters long and tan or dark brown. They have a dark, violin-shaped mark on their thorax, or the back upper torso. Brown recluses seek out warmth and dampness and are usually found in rotting wood or cardboard. Brown recluse bites can rarely cause potentially life-threatening necrosis, or flesh death. If you think you’ve spotted or been bitten by a brown recluse, let the experts know right away.


eastern massasauga rattlesnake

Eastern Massasauga Rattlesnake

The Eastern Massasauga is Michigan’s only venomous snake. During cold winter months, inhabits the wetlands and woods of the lower peninsula. Come late spring, they slither up from hibernation sites seeking food. Massasauga adults are about 2 to 3 feet long, with thick bodies, small heart-shaped heads, and vertical pupils. They are grey-ish, light brown, or tan with brown rectangular blotches on their backs and sides. They feed primarily on mice and voles.

Eastern Massasaugas are a special concern (endangered) species, and they play an important role in Michigan’s ecosystem. Avoid harming Massasaugas in the wild if possible. This shouldn’t be too hard; Massasauga are very timid, and prefer hiding to fighting. However, it’s important to remember that rattlesnakes are still wild animals, and must be handled with care and respect. Do not attempt to pick up or move a Massasauga; in fact, give it a wide berth. If you’re bitten, call 911 right away to receive help.


puss caterpillar

Puss Caterpillar

Caterpillars are probably about the last thing you think of when you picture dangerous pests, but watch out for this one nonetheless. The puss caterpillar (also known as the woolly slug) is the most poisonous caterpillar in the US. As a larvae, it undergoes several stages of development, or “instars,” until cocooning to metamorphosize into a southern flannel moth. The caterpillar derives its “woolly slug” nickname from the most identifiable of these instars. In mid-to-late stages, the caterpillar grows to around 1.2 to 1.4 inches long and develops a thick coat of hair that obscures its body.

This hair also obscures several hollow spines that contain poison. Coming into contact with these spines results in an intensely painful sting that can cause rashes, nausea, fevers, and cramps. Puss caterpillars feed on the leaves of oaks, elms, and sycamore. You may also encounter them on garden plants. If you’re stung by a puss caterpillar, remove any broken-off spines by hand, thoroughly wash the site of the sting, and contact your doctor.


Hopefully we haven’t made you afraid to live in your own state! While it’s true that we’ve got some dangerous pests up here, they’re all more afraid of you than you are of them. By learning to identify pests like these and staying out of their way, you shouldn’t have anything to worry about.

And, of course, if you do end up confronting dangerous pests in your home, you can give us a call anytime. Michigan’s big bads have nothing on us!

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