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10 Common Spiders in Colorado (Pictures)

Spiders are often feared and maligned, but many of them are actually harmless (and even beneficial) members of the animal kingdom. If you live in Colorado, there’s a good chance you’ve come across one or more of these common spider species. Here’s a closer look at some of the most common spiders you’re likely to encounter in the Centennial State.

10 Common Spiders in Colorado

From ground spiders and jumping spiders to house spiders and yellow sac spiders, below are among the most common spiders in Colorado, as well as their habits and how to deal with them if they become a nuisance:

1. Yellow Sac Spiders

Yellow sac spider on a leaf
Yellow sac spider on a leaf

Scientific Name: Cheiracanthium inclusum

The Yellow sac spiders are tiny and light-colored arachnids, typically between ¼ and ½ an inch in length. It has a dark stripe running down the middle of its abdomen and is sometimes mistaken for a young brown recluse spider.

They get their name from the silken sacs, where they spend much of their time, both as larvae and adults. During the day, yellow sac spiders often hide in these sacs, coming out at night to hunt for food. These spiders are generalist predators and will eat just about any small arthropod they can catch, including insects, mites, and other spiders.

While they don’t typically bite humans, yellow sac spiders can be aggressive if they feel threatened. If you do get bitten, it’s not usually serious and will only cause minor swelling, redness, and pain that subsides after a few minutes.

2. Cellar spiders

Long bodied cellar spider
Long-bodied Cellar Spider | image by Judy Gallagher via Flickr | CC BY 2.0

Scentific Name: Pholcidae

Cellar spiders get their common name from their habit of living in dark, secluded areas like cellars, garages, and crawl spaces. They are long-legged with small bodies and often confused with daddy-long-legs. Cellar spiders range in color from light brown to gray, and they spin large, messy webs which they use to catch insects.

These spiders are not aggressive and are not known to bite humans. When threatened, these spiders often bounce on their webs or drop to the ground and play dead. The females often carry their eggs in a sac attached to their jaw or chelicerae until they’re ready to hatch.

3. Banded Garden spider

Banded garden spider
Banded garden spider | by USFWS Mountain-Prairie via Flickr

Scietific Name: Argiope trifasciata

The banded garden spider is common in gardens and fields across Colorado. They are large with a distinctive black and white pattern on their abdomen, while the females are silver with yellow and dark-colored stripes.

The female spiders can grow up to an inch long, while the males are usually smaller. These spiders spin large, circular, and highly symmetrical orb webs, often seen in the center of their web with their legs outstretched.

The banded garden spider is not aggressive, and it’s not known to bite humans. When threatened, they may drop from their web or curl up into a ball. The female spiders lay eggs in a silken sac attached to their web, which they guard until they hatch.

4. Wolf Spiders

wolf spider close shot
Wolf spider | image by Jean and Fred Hort via Flickr | CC BY 2.0

Scientific Name:  Lycosidae

The wolf spider is a large, hairy spider. They are brown or gray and have markings on their backs that look like a wolf’s face.

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These spiders live in burrows in the ground and are often found in fields and woods. Wolf spiders hunt at night and are not aggressive. They will bite if they feel threatened.

Symptoms of a wolf spider bite are pain, swelling, and redness at the site of the bite. Their bite may also cause nausea, vomiting, and headache. If a wolf spider bites you, seek medical attention immediately.

5. Western Widow Spiders

Western black widow
Male Western Black Widow | image by Alan Moore via Flickr | CC BY-ND 2.0

Scientific Name: Latrodectus hesperus

Among common spiders in Colorado, the western widow spiders stand out for their distinctive black and red coloration. These spiders are part of the common cobweb spider family and build their webs in dark, sheltered areas.

Western widows are shy creatures that generally only come out at night but can sometimes be seen during the day if disturbed. These spiders are venomous, but their bites are typically not fatal to humans.

However, it can cause severe pain and other symptoms such as nausea, muscle cramps, and seizures. If you are bitten by a Western widow spider, seek medical attention immediately.

6. Brown Recluse

Brown recluse on denim
Brown recluse on denim | Image by Robby Lockeby from Pixabay

Scietific Name: Loxosceles reclusa

There are many common spiders in Colorado, but the Brown Recluse is one of the most feared. This spider is venomous, and its bite can cause serious health problems.

The Brown Recluse is a tiny spider about half an inch long. It is brown in color, with a distinctive violin-shaped marking on its back.

The Brown Recluse is shy and reclusive, and it is not aggressive. However, if it feels threatened, it will bite.

The venom of the Brown Recluse can cause tissue death or necrosis. In severe cases, it can lead to amputation or even death.

7. Funnel Web Spider

Funnel web spider on its cobweb
Funnel web spider on its cobweb | Image by Erik Karits from Pixabay

Scientific Name: Atracidae

Also known as the funnel weaver spider, this arachnid is commonly found in Colorado. Its legs have dark bands and a brown or gray carapace with light markings.

The funnel web spider is not aggressive and only bites when provoked. Its venom is not fatal to humans but can cause allergic reactions in some people.

8. The Hobo Spider

Hobo spider
Hobo spider | image by Géry Parent via Flickr | CC BY-ND 2.0

Scientific Name: Eratigena agrestis

The hobo spider is another common type of spider found in Colorado. It is brown or reddish-brown and has a v-shaped mark on its abdomen.

This spider is often found in homes and can be aggressive if it feels threatened. Its bite is not fatal to humans, but can cause serious health problems.

The hobo spider is commonly mistaken for the brown recluse spider because of its similar appearance. However, the hobo spider is not as dangerous as the brown recluse, and its larger size makes it easier to identify.

9. Tarantula

Baboon tarantula
Baboon tarantula | Image by Steve Buissinne from Pixabay

Scientific Name: Theraphosidae

The tarantula is one of the largest spiders in the world, with some species exceeding 10 inches in length. Although they are often feared because of their size and appearance, tarantulas are pretty docile and are only aggressive when provoked. They are typically found in warm, dry climates and prefer to live in burrows or trees.

Tarantulas generally only come out at night to hunt for food, mainly insects. When they catch their prey, they use their potent venom to paralyze it before wrapping it in webbing and devouring it whole.

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While their venom is not lethal to humans, a tarantula bite can cause intense pain and swelling. Despite their fearsome reputation, tarantulas are gentle creatures that make interesting pets.

10. Apache Jumping Spider

Apache jumping spider on a leaf
Apache jumping spider on a leaf | image by David Hill via Flickr | CC BY 2.0

Scientific Name: Phidippus apacheanus

The Apache jumping spider is a small but mighty creature native to the deserts of the southwestern United States. Despite its size, this spider is a skilled hunter, preying on larger insects such as crickets and grasshoppers.

The Apache jumping spider gets its name from its unique hunting technique: instead of spinning a web, it stalks its prey and then jumps on it to subdue it. This spider is also known for its large eyes and impressive vision. In fact, researchers believe that the Apache jumping spider has better eyesight than many birds of prey.

Thanks to these keen eyes, the Apache jumping spider is able to locate and pounce on its prey with surprising accuracy. So the next time you see a tiny spider leaping through the air, there’s a good chance it’s an Apache jumping spider on the hunt.