You might be amazed to learn that the arthropod species make up roughly 85% of known animals in the world! But not all of them are spiders. Spiders are part of the larger family of arthropods, which includes lobsters and crabs.
Benefits and Dangers of Spiders
Spiders are a species of active hunters that either trap their prey in webs or wait to ambush their intended victims. Spiders are very beneficial though, especially when they hunt and entangle other pests in the insect family.
So, if you’re one who becomes horrified at the thought of spiders, let’s see if we can give you a new perspective of how these eight-legged critters help us. While we’re at it, though, we do need to identify some of the dangers a few of them pose if they are antagonized.
For most, the least desirable way to be introduced to these hunters is to wander through one of their webs. However, spiders are not seeking human contact and would rather avoid it if possible. Encounters with these wildlife creatures in Colorado don’t occur every day and they can definitely be avoided.
If you keep a watchful eye out for their webs and avoid areas where spiders like spinning them, your exploration of this beautiful state can be enjoyed without any unwelcome introductions to the 28 known species of spiders considered native to Colorado. Learning about them should help you feel a little less anxious if you spot one.
6 Venomous Spiders of Colorado
The lists below contain some of the most common spiders found in Colorado, starting with six of the most dangerous ones. It’s worth mentioning that some spiders end up in the area by accident, after climbing into things like suitcases and cars. So, it’s possible you could find a completely new spider species along your journeys.
Brown Recluse Spider
The Brown Recluse has a unique violin-shaped marking on its back. Their poison is quite potent. If you’re bitten, seek medical attention quickly. At first, the bite will seem very innocuous, but it will advance to a very painful condition and is potentially deadly if not treated promptly.
Black Window Spider
The Black Widow is a very distinctive black spider with a red hourglass shape on its underside. Remarkably, only the females of this species are harmful, so it’s kind of a guessing game. Better safe than sorry though as the female’s venom is painful and could cause irreversible damage. Despite its deadly name, this spider’s bite is rarely fatal to humans.
The Hobo spider is another one you should probably avoid if possible. It delivers a venomous bite which causes necrosis like that of the Brown Recluse, though much more mild and not known to be deadly to humans. The venom can cause lesions which take months to heal and even cause headaches.
Yellow Sac Spider
The Yellow Sac Spider is one that is venomous, though the actual risk to humans is still relatively unknown. The venom can cause lesions which are painful. These spiders spin more of a sac-style web, so it should be fairly easy to spot if you’re being observant of your surroundings.
The Tarantula is a large, hairy spider which some people keep as a pet. The bite from these critters can cause some discomfort and the hair can be irritating if it gets on your skin. These guys are not known to cause any real harm to humans even though they are a bit scary looking.
The Ground Spider or Mouse Spider is a spider which burrows approximately three feet underground. Because of this, you’ll most likely come across this spider after a rainstorm when they are driven from their underground abode by rising waters. This spider is not normally aggressive to humans, though it can cross that line if provoked enough. Their bite is delivered with large fangs that can cause a nasty cut or gash. The venom is not particularly dangerous to humans, though in younger children it can make them sick.
12 Common Non-Toxic Spiders of Colorado
The following spiders are common to Colorado yet do not pose a real danger. They may startle you on occasion or deliver a minor bite that requires cleaning, but other than that they are harmless to humans.
Funnel Weaver Spider
The Funnel Weaver or Funnel Web spiders are pretty common in and around the home. These are quite harmless, however, they spin a heavy silk web which could incite a pretty active reaction if you walked into one. These guys are often confused with their lighter brown cousins, the Brown Recluse (mentioned above).
The Wolf Spider is one that refuses to spin a web, preferring to stalk its prey. It is quite aggressive towards those insects it views as food, however, this little guy really doesn’t want to be around you…at all. This spider can bite and cause some localized numbness, however, the venom does not pose a danger to humans. Keeping the bite area clean to avoid infection should be all you need. Colorado is home to multiple variants of the Wolf Spider, so keep an eye out for them.
Banded Garden Spider
The Banded Garden Spider is pretty true to its name, preferring to occupy space between plants in garden-style settings. It spins its web low to the ground and in the shape of an orb which makes it fairly unique as well. Another unusual aspect of this little critter, is that it keeps its dark underside pointed south, believed to allow it to absorb extra solar energy. Often, this spider sits with its legs in pairs, making it appear as if it has four thick legs, rather than eight skinny ones. This spider is not dangerous to humans and is a gardener’s favorite as it helps control bugs within garden plants and shrubs.
Apache Jumping Spider
The Apache Jumping Spider does not await their prey, choosing to pounce on their intended victims. These bug-eyed creatures can jump several feet and, in some cases, use their silk as a tether, swinging in an arc to propel them vertically not unlike a comic book superhero. These guys would rather jump away from things as large as a human and are not known to be harmful. They can bite, but their venom is not dangerous to humans.
The Woodlouse Spider or “Roly-Poly Hunter”, feeds primarily upon woodlice. As the secondary common name implies, this spider can pick up nicknames based upon the things they might be feeding on when they are seen. If you are not actively picking up logs, rocks and bricks, the likelihood of finding one of these arachnids is pretty remote. These spiders have fairly large fangs considering their size. If you are bitten, it will likely be painful because of these fangs, but it shouldn’t require more medical attention than keeping the site clean to avoid infection.
Red Stripe Spider
The Red Stripe Spider prefers ants and other insects as prey. Using its back six legs to walk while raising its front pair to mimic the antennae of ants, gives it the appearance of an ant. This behavior masks their true intentions to their prey. This spider is considered harmless to humans, though.
Long-Legged Sac Spider
The Long-legged Sac Spider is a nocturnal creature, preferring to stalk its prey under the cover of darkness. The only web this spider spins is a small sac-like web to sleep in snug as a bug. Not really preferring to hang around humans, this spider will bite if it feels threatened. The bite can become red, irritated, and be painful for a short time (one or two hours). The bite will heal on its own, so keeping the bite clean should suffice.
Running Crab Spider
The Running Crab Spider prefers to chase its prey down rather then spin a web and wait. So as you can imagine, they are quite fast, easily out-maneuvering your hand should you feel the urge to catch one. A well-camouflaged mottled brown coloring on this critter makes it hard to see, but that’s okay, this species is not harmful to humans.
Striped Fishing Spider
The Striped Fishing Spider lives around lakes and docks giving it the nickname of “Dock Spider”. This critter skims along the water’s surface hunting insects, tadpoles and very small fish. These spiders will run away when you approach and unless you intentionally grab one or pose a threat to a mother protecting her young, the likelihood of being bitten is slim. Although it is a rather large spider, it is not considered harmful to humans.
Eastern Parsons Spider
The Eastern Parsons Spider is another nocturnal hunter preferring to hide in small cracks or under rocks during the day. It’s generally found in woodpiles and around rocky terrain, though it will be enticed into the home if there are plenty of insects to hunt. This spider’s bite can break the skin but it is no threat to humans.
Bridge Orb Weaver
The Bridge Orb Weaver is a spider that prefers to reside on steel objects. Bridges and other steel structures, particularly near lights, are its most favored locations. Its bite can break the skin, however, the toxicity of their venom won’t cause any damage to humans.
The Cellar Spider, or more commonly called Daddy Long-legs, is really common. Preferring to eat ants, these creatures will also hunt other insects including other spiders. These house-dwellers appreciate a warm and “inviting” home that protects them from the weather. They can be found most anywhere though, such as rock piles and loose mounds of leaves. One big misconception is these guys are harmful to humans. They do have venom, though it is not considered toxic to humans.
Spiders can be scary to some folks and there are some that carry a fair amount of danger to humans. Most are actually out there doing a lot of good work at keeping pest insects under control, as do many of Colorado’s native birds. In most cases, the bites are of little consequence to people.
As with anything involving the injection of venom, whether it is considered harmful to humans or not, there are inherent concerns. Some people may have allergies to the venom while other people’s immune systems are less tolerant. It’s important to note that smaller children are more susceptible to the effects of some of these venoms.
As you explore the great outdoors of Colorado or settle into a new home, be confident that most spiders you might see are fairly friendly “guests” to have around, just like most snakes are harmless. They don’t want to bother you any more than they want to be bothered, so if you can handle their presence, it might be worthwhile letting them go about their business.