Let’s talk about Michigan spiders: Some to fear and one to keep as a house guest

Take a virtual tour of Michigan State University’s Bug House

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I don’t know about you, but I’m starting to see a lot of spiders around my house.

Up until I started doing some digging for this article, I didn’t know much about spiders. The little knowledge I did have was mostly based on instinct (I either ran away or found something to squish it with.)

I did have a spider living in the side mirror on the driver’s side of my car for awhile. He (or she) would make a web from the edge of the mirror to the door and when I started driving the spider would duck behind the glass.

We had an agreement that as long as the spider kept to its designated area I would leave it be. One day, the spider was just gone. I’m not sure which type of spider it was, but it was alright in my book.

If you enjoy looking at spiders, then you might like this Reddit page which is dedicated to spiders being bros.


Brown Recluse

Brown recluse spider.

Michigan is not in the native range of the brown recluse, but they have been found in at least 10 Michigan counties as of 2018. They are believed to have traveled to Michigan in people’s suitcases or boxes.

  • Family: Sicariidae
  • Size: Quarter to a half inch long
  • Where are they hiding? Typically outside under rocks, utility boxes and woodpiles. Indoors they can be found in undisturbed areas like inside boxes, among papers and seldom-used apparel and shoes. They can also be found under furniture, in crevices of window moldings. They also hide in closets, attics, crawl spaces and basements.
  • Are they dangerous? The brown recluse spider tends to bite in defense and does not bite humans instinctively. Their bite results in a stinging sensation followed by intense pain as long as six to eight hours later. Symptoms include restlessness, fever and difficulty sleeping. The bites rarely kill people but you should seek medical attention.

READ: Venomous brown recluse spider found in 10 Michigan counties: What to know


Northern black widow spider

Black widows are more common in the western Lower Peninsula. They have a distinctive hourglass marking on the underside of the abdomen. The marking may be split in the middle and they may have a series of red spots along the dorsal midline of the abdomen. They also could have a series of lateral white stripes on the abdomen.

  • Family: Theridiidae
  • Size: 3 to 10 mm
  • Where are they hiding? Old stumps, hollow logs, fallen fence posts, abandoned animal burros or piles of crush. Or they’re in the corners of sheds and crawl spaces.
  • Are they dangerous? Bites are not common because the spider is timid. There is less than 1 percent mortality of persons bitten by black widows. The toxin affects the central nervous system. The severity of the bite depends on age, size and sensitivity of the victim. Pain is immediate and lasts for 1 to 3 hours or up to 24 hours.

Click here to read more about the northern black widow spider.


Wolf Spider

Wolf spider.

Wolf spiders feed on large insects and other spiders. They’re not known for being particularly aggressive, but they will be in self-defense. They tend to hunt their prey while on the move instead of making a web. Some burrow into the ground and ambush their prey as it crawls past. Because of their size, wolf spiders are often mistaken for an escaped pet tarantula.

  • Family: Lycosidae
  • Size: Large
  • Where are they hiding? Your basement, crawlspaces and breezeways. (But in low numbers, so usually only one or two of them are hiding there.)
  • Are they dangerous? Their venom is not particularly dangerous.

Click here to read more about wolf spiders.


Jumping spider

Jumping spider (Family Salticidae) (Michigan State University)

Jumping spiders are known for -- you guessed it -- jumping. They pounce on their prey. They are predators, they eat insects and other spiders.

They don’t spin webs. Instead, they make little silken shelters under leaves or bark. All species are small. They hunt during the day. Most are brightly colored. They have eight eyes and are known to have the sharpest vision of all spiders.

  • Species: Family Salticidae
  • Size: Usually less than 15mm long
  • Where are they hiding? They’re probably in your garden.
  • Are they dangerous? They’re more likely to run away from humans. While they can bite, the bite is not poisonous. The bite is usually asymptomatic or slightly painful.

Click here to read more about jumping spiders.


Yellow sac spider

Yellow sac spider (University of Nebraska)

Yellow sac spiders are active hunters. They search for their prey instead of using a web. If you’re going to encounter one, it will likely be at night.

They bite when they become trapped. The bite of C. inclusum is more destructive than the bite of C. mildei. People usually get bitten by C.inclusum while outside gardening during the summer. C. mildei is known to bite without being provoked.

Most C. mildei bites are painless and don’t require medical attention unless the person is particularly sensitive to spider bites. C. inclusum bites are usually very painful with a burning sensation lasting for up to an hour.

  • Species: Cheiracanthium inclusum and C. mildei
  • Size: Females are 5-10 mm and males are 4-8 mm.
  • Where are they hiding? Walking on foliage, under leaf litter, stones, boards and on buildings. They could be under window sills and siding. They also hide in the corners of walls and ceilings within homes.
  • Are they dangerous? Depending on the species of yellow sac spider the reaction to the bite can be more or less severe. They’re not known to be deadly. Their bites can be misdiagnosed as a brown recluse bite.

Click here to read more about yellow sac spiders.


Common house spider

Comb-footed spiders (Michigan State University)

This is an extremely common spider in North America. They build webs and usually try to remain quiet and efficient. They are usually dull in appearance with brown patterns.

They are not aggressive and have poor vision. These types of spiders try to stay close to their webs. Many species share a body shape and size that makes them similar to widow spiders, the main difference being the color.

  • Family: Theridiidae
  • Size: Their average body size is a quarter-inch long.
  • Where are they hiding? They build webs in secluded locations.
  • Are they dangerous? They are not known to bite people frequently. Their venom is not known to be dangerous to humans. Their bites can have recluse-like effects.
  • Other names: Comb-footed spiders, cobweb spiders, tangle-web spiders, American house spider.

Click here to read more about common house spiders


Want to learn more about arachnids or insects? You can take a virtual tour of Michigan State University’s Bug House via the embedded videos below. Click here to read more about the brown recluse and other spiders.

Bug House tour part 1:

Bug House tour part 2:


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