What they look like: These spiders are on the smaller side and have a round abdomen, says Marc Potzler, a board-certified entomologist and technical services manager with Ehrlich Pest Control. “Their web often looks very tangled or messy,” he adds.

Where you’ll find them: They like to hang out in dark, concealed areas. “They hide in corners, underneath cabinets, in basements, sometimes in garages around the windows where flies may be active,” Potzler says.

Size: Nickel-sized or less than a quarter of an inch (0.6 centimeters) long

Color: Gray or brown, sometimes with white markings

Can they harm you? Nope.

What they look like: There are over 200 species of wolf spiders crawling around, Potzler explains. And, since they’re hairy they can sometimes be mistaken for tarantulas. Also worth noting: “These are nomadic spiders that don’t spin webs to catch their prey—they hunt them down,” says Howard Russell, an entomologist at Michigan State University.

Where you’ll find them: You can find wolf spiders where other insects reside—like garages, basements, sheds, and other dark, enclosed areas, according to Potzler. You can also find wolf spiders outside in various locations: In our around debris, underneath boards, or in gaps around your home.

Size: Ranges up to 1 and 1/2 inches long

Color: Gray, brown, or black

Can they harm you? No: Russell assures that these spiders “would prefer to hide than bite.”

What they look like: The infamous black widow has a shiny black color along with their signature, red hourglass-shaped marking on their underside, explains Potzler. “They may also have red markings going up its back,” he adds.

Where you’ll find them: Black widows prefer to dwell in places containing edges and corners, as well as tall grass, Russell notes. You can also find them hiding in mailboxes or garages, he adds.

Size: 1/4 to 1/3 of an inch long

Color: Black and red

Can they harm you? “This is one of the few species of spider that can be dangerous to people,” says Potzler. “There are approximately 2,200 bites reported each year, but there has not been a death related to a widow spider in the U.S. since 1983.” Intense pain, muscle stiffness, possible nausea, and vomiting are the telltale signs of a black widow spider bite, and these symptoms will likely occur within a few hours after being bitten, Potzler explains. Head to the ER ASAP if you suspect you’ve been bitten to get immediate treatment.

What they look like: The brown recluse is a brown spider with a distinct “violin-shaped marking” on the top of its head and down its back, Potzler says. They also have six eyes instead of the eight that many other spiders have.

Where you’ll find them: The brown recluse likes to hang out in undisturbed corners of homes, in sheds, and in basements or cellars. “Many bites occur because the spider is hiding in folded towels and sheets, underneath a pile of clothes on the floor, or in shoes in a closet,” Potzler says. “If you live in an area where brown recluse is common, it’s a good idea to shake out your clothes and shoes, or wear gloves if you are working in your shed or garage.”

Size: Female bodies range from about 1⁄4 to 1⁄2 an inch with a leg span over 1 inch and males are generally half the size of females.

Color: Brown

Can they harm you? Yes. “The recluse can cause serious damage to people,” says Roberto M. Pereira, Ph.D., an insect research scientist with the University of Florida. “Bite sites are a serious problem.” A brown recluse bite can cause necrotizing wounds (meaning, it kills the cells and tissues around it), so you’ll want to see a doctor immediately if you think you’ve been bitten by one, Russell says.

What they look like: You’re probably pretty familiar with this one, but just in case: It has one round body part and very thin, long legs coming off of it.

Where you’ll find them: They like to live outside, they can sometimes hide under siding or be found on and under decks. “For the most part, you’ll find them on the lawn or up in trees,” says Potzler.

Size: Bodies range from the size of a pinhead to a quarter

Color: Brown

Can they harm you? No. “Contrary to myths found on the Internet, daddy longlegs are not venomous enough to kill a horse,” says Potzler. “They do not have venom glands. They pose no harm to humans.”

What they look like: Hobo spiders are tannish-brown and the top of the spider may look mottled, with darker and lighter spots, Potzler says. They look pretty hairy and have spiny hairs coming off the legs.

Where you’ll find them: While they’re usually outside, they sometimes venture indoors. “It can hide in clothing, beds, and shoes,” Potzler says.

Size: About 1/2 to 5/8 inches long

Color: Light brown with pale markings

Can they harm you? Yes. “The hobo spider can inflict a painful bite that results in localized red swelling and some pain, but no necrotic lesion,” Potzler says. Usually, symptoms will get better within 24 hours with OTC painkillers and ice.

What they look like: There are more than 300 species of these, and they all look a little different. “They are most easily distinguished by their very large, front middle set of eyes, although most people probably don’t want to get close enough to look at their eyes.”

Where you’ll find them: They can be just about anywhere in your house. They don’t build webs, but they’re what Potzler calls “active daytime hunters” so you can spot them at any time. “You may see them both inside climbing walls or ceilings, or hanging out in attics, or outside scaling buildings and trees,” he says.

Size: Ranges from 1/8 to ¾ of an inch

Color: “Their colors can vary from solid black with distinctive markings, to striped like a zebra, and some have iridescent markings,” Potzler says.

Can they harm you? Not really. While Russell says these spiders “may bite in defense,” it shouldn’t cause any issues for you.

What they look like: The spider will build a tent-like structure out of silk. “They hide in the sac during the day and then hunt at night,” Potzler says. They usually have a dark V shape on their bodies.

Where you’ll find them: Their webs are usually found at the top of the wall where it meets the ceiling or corner, Potzler says. He’s found them most often in living spaces, like living rooms, bedrooms, and kitchens.

Color: A pale beige or yellowish shade

Size: Body ranges from about 1/4 to 3/8 of
an inch in body size

Can they harm you? It’s not common for these spiders to bite “but there have been some reports of hospitalizations for individuals who have compromised immune systems or pre-existing health conditions,” Potzler says.

What they look like: These are the spiders that build huge webs that you can see in the morning covered in dew. “Orb weavers spin their web each day and then tear it down and rebuild the next day,” Potzler says. They can have spiny or smooth abdomens. There are tons of species and some can be difficult to distinguish from other spiders.

Where you’ll find them: They like to build their webs where they’re most likely to grab flying insects, Potzler says. They may build webs on decks or the exterior of your house, especially if you have outside lighting (which attracts the flying insects they like to eat).

Size: The larger species can exceed a body length of 1 inch
while the smallest species rarely reach ¼ of an inch

Color: Usually brown or gray

Can they harm you? Not really. While they can bite, it won’t usually cause an issue for most people, Potzler says.

What they look like: It’s a “very ordinary-looking” brown spider, Potzler says. It can be confused with the brown recluse, but grass spiders have long spinnerets (finger-like appendages at the end of the abdomen), which the brown recluse does not have, he says.

Where you’ll find them: They tend to like to hang out around the foundations of homes, but Potzler says that sometimes males will find their way inside while looking for a mate.

Size: Females are about ½ to ¾ inch long (not including legs) and males are slightly smaller

Color: Dark brown

Can they harm you? They can bite but “there are no reported cases of medical significance,” Potzler says.