Michigan is home to many species of spider. Most of them are quite small, and harmless, although there are a couple of them that you need to be careful around. Here are some of the most common spiders in Michigan.
18 Common Spiders in Michigan
1. Starbellied Orb Weaver
Scientific name: Acanthepeira Stellata
A striking and unforgettable species, the starbellied orb weaver is also widespread- it can be found from southern Canada all the way down into northern Mexico, and from coast to coast. Like many orb weavers, it’s a small spider, with the females only growing to about half an inch long, and males are considerably smaller.
It’s large abdomen is adorned with several spikes that give it a crown-like appearance, especially since it protrudes over the cephalothorax, making it appear as if it’s sitting on top of the spider’s head.
They spin a vertical, twelve-inch wide web a few feet above the ground, and then sit in the very center of the web, waiting for their prey to get stuck in it. When it feels threatened, it drops from the web and plays dead until the danger has passed. Bites from this spider are essentially unheard of, and it’s not considered dangerous to humans.
2. American Grass Spider
Scientific name: Agelenopsis
This is a large genus of spiders that consists of many different species, and the taxonomy of each species isn’t always clear, since they are all similar in appearance and their ranges overlap. They’re also quite difficult to tell apart from wolf spiders, which have a similar appearance and range.
The biggest difference between grass spiders and wolf spiders is that grass spiders actually build and use webs, while wolf spiders do not. A grass spider’s web is horizontal, and leads to a funnel at one end, in which the spider hides.
The web isn’t sticky, and it’s not used to trap prey. Instead, when an insect crosses the horizontal webbing, the spider hiding in it’s funnel can feel the vibrations through the web, and it runs out to ambush it’s prey.
3. Giant Lichen Orb Weaver
Scientific name: Araneus Bicentenarius
The heaviest orb weaver, although not the largest, the giant lichen orb weaver can grow to one inch across, and it’s massive, thick abdomen is the reason for its weight. It has orange legs with black bands on them, and intricate green and gray markings on it’s abdomen.
It spins a huge web that can be as big as eight feet across, making it one of the most impressive spider webs you’ll ever see in Michigan. While most orb weavers like to sit in the middle of their web, the giant lichen orb weaver prefers to wait along the edges of the web.
This is likely due to it’s large size- a spider this big sitting in the middle of it’s web all day long would be easy pickings for predators. It’s a nocturnal spider, and so it tends to remain inactive along the edge of the web all day long.
4. European Garden Spider
Scientific name: Araneus diadematus
As you may have guessed from the name, this spider isn’t native to Michigan. It’s been introduced to all of the northern US, however, and it’s become quite common. It can be identified by the white markings on its abdomen which form the shape of a cross. While it’s body rarely exceeds ¾ of an inch long, when you include it’s legspan, it can easily measure over an inch across.
It’s web is a vertical, circular shape that’s effective for catching flying insects. These spiders are rarely seen during the day, when they tend to hide near the edge of the web. As the sun begins to go down they can be observed crawling out to the center of their web, where they’ll hang with their head pointed toward the ground, waiting for their prey to be trapped in the web.
5. Cat-faced Spider
Scientific name: Araneus gemmoides
Also called the jewel spider, this is a orb-weaver that’s named for the appearance of its abdomen. When viewed from the front, it’s abdomen gives the distinct impression of a cat’s face. Some people perceive it as being diamond-shaped, though, which led to it’s other common name, the jewel spider.
It can grow up to an inch long, and it’s characterized by short legs and an oversized abdomen. Their bite is considered harmless to humans, and since they often build their webs around homes, they’re actually a beneficial species that can help with pest control.
6. Marbled Orb Weaver
Scientific name: Araneus marmoreus
An orange spider with a darker marbling along it’s abdomen, this species is also known as the pumpkin spider. This is only in part because of their orange color; it’s also because they tend to be most active during the fall, and at this time of year their abdomens also become more swollen and round, like a pumpkin.
They aren’t always orange, though. Some individuals can be yellow with black marbling, some are cream-colored and some are even red. They grow to be about an inch long.
Their web is typical of orb-weavers: a large, round vertical web suspended high enough to capture flying insects. They sit and wait right in the center of the web, waiting for their prey to fly into the trap.
7. Shamrock Spider
Scientific name: Araneus trifolium
This species can come in several different colors, so the only surefire to identify one is to look at the legs. Shamrock spiders will usually have white bands on it’s legs, a feature no other orb weaver in Michigan shares.
They build a large web, often over 2 feet across. Like many orb weavers, they rebuild their web every night, completely tearing it down and constructing a brand new web.
The bite from this spider is similar to a bee sting, but it’s unusual for them to bite. Since they spend almost all of their time in their webs, it’s rare for them to be in a position to bite a human.
8. Black and Yellow Garden Spider
Scientific name: Argiope aurantia
This is one of the largest spiders in North America, and quite possibly the biggest spider in Michigan. There’s no mistaking one of these, and there’s no way you would fail to see one if it’s moved into your yard.
The body alone can be longer than an inch, and when you include the legs adult females can easily grow to over three inches across. They have bright yellow and black markings on their abdomen, and deep black legs with a silvery-white cephalothorax.
They construct huge webs, often 2-3 feet across or more, and their web has a distinctive zig-zag pattern that runs straight through the center of it. It’s believed that this pattern makes the spider appear larger and more dangerous to predators. They sit right in the middle of their web all day long, and their huge size, bright colors, and the height of their web- often well above head-height for a human- makes them easily visible.
9. Banded Garden Spider
Scientific name: Argiope trifasciata
A close relative of the black and yellow garden spider, and very similar in appearance. The quick way to distinguish it is that it’s abdomen has a base color of white, with thin, horizontal bands of black and yellow. They also tend to have orange legs with dark brown bands, instead of the black legs of the black and yellow garden spider.
They’re the same size as the black and yellow garden spider- three inches across when the legs are included. Webs are typically about 2 feet across but 6-foot webs are not uncommon, and like their cousins they build a distinctive zigzag pattern in the middle of it. Despite its large size, it’s not considered dangerous to humans, and it’s bite is no worse than a bee sting.
10. Red-spotted Ant Mimic
Scientific name: Castianeira descripta
This is a fascinating species that has evolved a unique appearance and behavior in order to fill a specific ecological niche. It doesn’t spin a web at all- instead, it uses trickery and subterfuge to hunt it’s prey.
It looks like an ant, and it even acts like one. In fact, it walks with it’s two front legs held up in the air in front of it, both to mimic an ant’s antennae and to give it the appearance of having only six legs. In this way, it tricks the ants it feeds on into letting it get very close, and then attacks when their guard is down.
Because is a small, black, hairless spider with a red hourglass marking on it’s abdomen, it’s often confused with the black widow. However, on this species, the hourglass mark is on the top of it’s abdomen, rather than the underside.
In addition, it’s cephalothorax and abdomen are much close in size, whereas the black widow has a very small cephalothorax and a large, rounded abdomen. Black widows also build webs and live in them, while the red-spotted ant mimic doesn’t use webs.
11. Northern Yellow Sac Spider
Scientific name: Cheiracanthium mildei
This spider’s characteristic yellow-green color makes it fairly easy to identify. During the day, it tends to hide under a blanket of silk in the leaf litter of the forest floor. It does enter homes from time to time, though.
They’re a small spider, about ⅜ of an inch long, and even when the legs are included they only about ⅝ of an inch across. They are a hunting spider, and so they don’t use a web to catch their prey. Instead, they build a cocoon-like structure of silk to hide in during the day.
You can often find these sacs in the crease where the wall meets the ceiling or under window sills. If you spot a little silk cocoon in one of these spots during the day, there’s a good chance a little spider is hiding inside.
If you see one of these sacs, leave it alone. The spider isn’t aggressive, but it’s bite is one of the more painful spider bites, causing swelling and even leaving open sores in some cases.
12. Leaf-curling Sac Spider
Scientific name: Clubiona
This is a genus of spiders that all have a similar appearance, and many have overlapping ranges. They typically have a dark brown abdomen and lighter brown cephalothorax and legs. In fact, sometimes the head and legs appear to be translucent.
The name comes from their habit of hiding their egg sacs in the leaves that are folded over and sealed shut with spider silk, creating an excellent hiding spot for them. Like most sac spiders, their bite is quite painful, but not ultimately dangerous to humans or to larger pets.
13. Fishing Spider
Scientific name: Dolomedes tenebrosus
This species has patchy, brown and black coloring all over it’s body, with a black mask around the eyes. They can be quite large, with females reaching over 4 inches across including their long legs.
They’re semiaquatic, spending most of their lives near water. Instead of using a web to catch their prey, they sit at the water’s edge with their front legs resting on the surface of the water, sensing the vibrations of whatever is swimming underneath them. In this way they can catch aquatic insects as well as small fish and tadpoles.
14. Woodlouse Spider
Scientific name: Dysdera crocata
This spider has a fearsome appearance because of it’s abnormally long fangs and legs. It’s a hunting spider, so it relies on speed and power to catch and kill it’s prey, which consists almost entirely of woodlice.
The cephalothorax is a deep reddish brown and the abdomen is a lighter brown color. The two body segments are almost the same size, with the abdomen being just slightly larger. Their body length is about half an inch, and when you include their legs they can be about an inch long.
While it’s disproportionately long fangs give it a scary look, it’s quite harmless. The bite may be a bit painful, but its no worse than a bee sting.
15. Candy-striped Spider
Scientific name: Enoplognatha ovata
This spider is native to Europe but it’s been widely introduced in Canada and the United States. It’s one of the cobweb spiders, which means it’s related to the black widow. This is evident when you pay attention to it’s body shape- a large, rounded abdomen and a small cephalothorax- and it’s chaotic cobweb.
Beyond that, though, it’s completely different. It has a greenish white body with bright red stripes along the top of the abdomen. Fortunately, unlike it’s relative the black widow, the candy-striped spider is harmless, and it’s bite is not medically significant.
16. Northern Black Widow
Scientific name: Latrodectus variolus
About half an inch long, 1.5 inches when the legspan is included, this small spider is one of the most feared species in the world. It’s the most venomous spider in North America, but it’s actually quite rare for a bite to be fatal.
\It’s common for them to not inject any venom with they bite, and when they do, medical treatment is fairly straightforward. In addition, they aren’t aggressive, and only bite as a last resort in self defense.
They build chaotic, tangled-looking cobwebs and often hang upside down from them, making their red hourglass marking easily visible. They tend to build their webs in dark, secluded places like basements and woodpiles.
17. Wolf Spider
Scientific name: Lycosidae
Wolf spiders are a large genus of hunting spiders, and the individual species are impossible to identify without examining them under microscopes. Many species grow to over three inches across, making them quite large. They’re also fast.
These are hunting spiders, which rely on their speed to chase down their prey. They don’t spin webs at all, except when laying eggs. The female will construct a silk egg sac and attach it to her abdomen to carry the eggs around with her wherever she goes.
Wolf spiders frequently enter homes, but rarely stick around long. They wander a lot in search of prey, so if you find one in your house you can catch it in a cup and place it in your yard. It’s unlikely it will return to your home.
18. Common House Spider
Scientific name: Parasteatoda tepidariorum
This species is found all over the continental US, and it’s quite likely you have more than one of them in your home right now. At first glance, they’re similar in appearance to the black widow, but they’re paler in color and have banded legs. They’re also smaller than the black widow.
While they’re venom is actually similar in composition to the black widow’s, it’s nowhere near as potent, and they aren’t considered dangerous to humans. In fact, they’re quite beneficial, since they eat many household pests.
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