5 Dangerous Spiders Found in Colorado

Most spiders that you see probably won’t hurt you. However, as you’re getting out there and exploring this beautiful state, it’s important to know which types of bugs to watch out for. Here’s our list of potentially dangerous spiders in Colorado and where you should watch out for them. Note that most of the time, interactions with dangerous spiders are rare and quite preventable. However, one step of prevention is awareness.

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1. Brown Recluse

To be clear, brown recluse spiders are very rare in Colorado, but there have been confirmed cases in which they’ve been present. Though Colorado is outside of the typical range of the brown recluse, this spider can be transported to a new location by relocated residents – something Colorado is full of. Their bites aren’t generally painful at first, but do carry a potentially deadly venom. Though their fangs can’t penetrate most fabrics, they are notorious for nesting in clothes and gloves that are undisturbed for long periods of time. If you’ve recently moved to Colorado or are around possessions of someone that has recently moved, keep an eye out for this one.

Editor’s Note: While Colorado is not in the typical range of the brown recluse, it’s important to be aware and know how to identify them as there have been a notable number of cases when they’ve been transported from another region. This is a growing concern, as more people are moving to Colorado from other areas of the country.

2. Hobo Spider

Causing necrosis in a similar but more mild fashion than the brown recluse, the hobo spider is generally referred to as an “aggressive house spider”. Bites are not known to be fatal to humans and there are no issues with roughly 50% of bites. That being said, symptoms of bites can include painful headaches, blisters, and lesions that can take several months to heal. Colorado is one spot where these spiders are commonly found.

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3. Black Widow

One of the most infamous spiders around, the black widow is known for its red markings. Believe it or not, only the females are actually dangerous to humans. Their bite is extremely painful and can cause permanent damage, though rarely results in death with modern medical treatment.

There are two species of “widow” spiders, with the western widow (Latrodectus hesperus) being most common in Colorado.

4. Tarantula

Though they might look intimidating, tarantulas can’t really cause serious damage in most cases. However, their bites are painful and their hair causes irritation so they should be handled with care.

Don’t believe tarantulas are here? Go watch thousands cross one Colorado valley.

5. Yellow Sac Spiders

Victims of yellow sac spider bites are advised to get medical attention immediately as the effects of these encounters is still relatively unknown. Their venom can cause small lesions on humans, though whether or not it is necrotic is up for debate. We debated including this one on this list as the verdict of risk is still out, but we figured it’s better to be safe than sorry.

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