How To Identity The Most Common Utah Spiders

The dangers of spiders are well documented throughout history. Due to their creepy-crawly nature and the dangers posed by some of the more venomous species, spiders have become an international sign of horror. The good news? Not all venomous spiders have the ability, or even the desire, to seriously harm you. The bad news? Certain spiders can and will cause injuries if they feel threatened. Holmes Lawn & Pest wants to make sure you know what to watch out for when it comes to dangerous spiders on your property. This post is designed to give you a better idea of which spiders are dangerous and how you can identify them.

Dangerous Spider Species In Utah

Western Black Widow (Latrodectus hesperus)

The most feared of all venomous spiders in Utah, and in the United Stated as a whole, are black widow spiders. Black widow spiders are unquestionably the most dangerous spiders you could encounter in Utah. The black widow spiders in Utah are likely to be western black widows. The males are considerably smaller, they are usually a brown to greenish color, and their bites do not cause serious or life threatening injuries. The female black widow spider has the shiny black body and red hourglass shape under its plump abdomen that most people envision when they think of a black widow. Though the red hourglass is a reliable indicator, not all female black widows will have the same markings. Some black widows may be solid black, or some may have round or striped markings. Regardless of the shape of the markings, if an adult female black widow DOES have markings, they will always be bright red.

Western black widows…

• weave asymmetrical/erratic webs to catch prey.
• prefer dimly lit and secluded areas.
• can sometimes be found in attics, basements, and garages.
• spend most of their lives close to their webs (females).
• do not always inject venom when they bite.
• can inject venom and cause vomiting, dizziness, spasms, necrosis, and death (rare).

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Brown Recluse (Loxosceles reclusa)

Brown recluse spiders are not a common species of spider found in Utah, but they have been identified in parts of southern Utah on rare occasions. Similar to brown recluse spiders are desert recluse spiders, and some experts believe all reports of brown recluses in Utah are actually attributable to desert recluses. These two spiders are often difficult to differentiate, but the same level of caution should be taken with both species. Including the legs, these spiders are typically no bigger than the size of a quarter. They are a brown to tan color, but they can occasionally have pale black abdominal areas, and desert recluses are occasionally a lighter shade of brown. Brown recluses, and sometimes desert recluses, have markings on their backs that are frequently referred to as violin shaped. Another easy way to identify a recluse spider is by its six eyes; most spiders have eight eyes, and only a few other species have six.

Desert and brown recluse spiders…

• weave small webs for nesting, not catching prey.
• prefer dry, secluded habitats.
• are nocturnal hunters.
• enjoy solitude and usually bite only when they are physically touched.
• do not always inject venom when they bite.
• can inject venom and cause tissue damage, including necrosis.

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Yellow Sac Spider (Cheiracanthium inclusum)

This is one of the most common spiders found in Utah. The colors of yellow sac spiders are typically a pale yellow or tan, with a greenish tinge around their abdominal region. Their legs are mostly the same shade of yellow as their bodies, but the very tips of their legs are much darker. All eight eyes of the yellow sac spider are the same size and are found in two rows at the front of their heads. Including their legs, yellow sac spiders can grow up to a length of ⅝ of an inch. Yellow sac spiders are commonly misidentified as brown recluses due to their similar appearances.

Yellow sac spiders…

• weave cocoon-like sacs for hiding during the day.
• are nocturnal hunters.
• are often found in their sacs in corners of ceilings and walls.
• prefer to hide outside under leaf litter in warm weather.
• are unusually aggressive.
• inflict painful bites that could become infected.

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Wolf Spider (Hogna spp.)

There are several different species of wolf spiders in Utah, but differentiating them can be quite difficult due to the subtlety of the variations. A definitive characteristic of wolf spiders is the eye placement. Wolf spiders have eight eyes–two on the top of its head, two in the front of its head, and a row of four small eyes underneath the two forward-facing eyes. Wolf spiders vary widely in size depending on the species, with measurements anywhere from ⅜ of an inch to 3 inches long, though the vast majority in Utah are around 1 ½ inches. Wolf spiders are mistaken for tarantulas due to their hairy bodies and large fangs.

Wolf spiders…

• do not spin webs.
• stalk, hunt, and ambush their prey nocturnally.
• feed on insects and small invertebrates.
• are typically found on the ground level.
• produce a painful bite that will swell, but it is not life threatening.
• leave large fang marks when they bite.

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Hobo Spider (Eratigena agrestis)

This species of spider belongs to the funnel web family. Hobo spiders are notoriously difficult to identify, even to a trained eye. They are frequently mistaken for giant house spiders or wolf spiders; however, there are some subtle variations in appearance that will always indicate whether you are dealing with a hobo spider. Unlike similar spiders, the hobo spider has solid-colored legs that do not contain any bands of color, and its legs are shorter than a giant house spider’s legs. They are mostly brown, but they have a grayish abdominal area, with brown to yellow markings. Unlike larger species, the hobo spider rarely grows larger than 2 inches long.

Hobo spiders…

• weave non-sticky, funnel-shaped webs.
• hide and pounce on prey after feeling vibrations on their web.
• are often found outdoors around bushes, rock piles, wood piles, etc.
• feed mainly on insects, but they have been known to prey upon other arachnids.
• can inject venom, but the potency is debated.
• were taken off the dangerous spider list by the CDC in 2017.

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Golden Huntsman Spider (Olios fasciculatus/giganteus)

You have probably seen online videos of people finding huntsman spiders in their homes. The golden huntsman spider has been known to inhabit areas of Utah. They are also known as giant crab spiders because of their robust bodies and exceptionally long legs, similar to that of a crab. Golden huntsman spiders can grow up to 6 inches long and have brown to black bodies, and the golden huntsman is typically a yellowish color. Their bodies are generally flat, and they have two rows of four eyes.

Golden huntsman spiders…

• do not spin webs.
• hunt at night via chasing and jumping on prey.
• are typically found near shrubbery and rocks.
• can climb walls very well for a large spider.
• are aggressive to humans only when guarding eggs (females).
• have a low number of reported bites, which are not life threatening.

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Camel Spider (various genera/species)

Though it is even more terrifying looking than the huntsman spider, the camel spider is not technically a spider, but it is part of the arachnid family. These little monsters can grow as large as 6 inches in length, but the types of camel spiders commonly found in Utah are typically smaller. They have tan to brownish bodies that have tiny hairs all over them. Their mouthparts have strong pincers and sharp, tiny “teeth” that can cut through bones of their ground-dwelling prey. Camel spiders also have a trachea, which allows them to take in oxygen and move around more quickly than most spiders.

Camel spiders…

• do not spin webs.
• prefer desert climates, hiding under rocks to escape the sun.
• produce a hiss sound to warn predators.
• can feed on beetles, wasps, other insects, and even small rodents.
• cut prey into pieces with their sharp mouthparts.
• are not venomous, but their bites are painful and prone to infection.

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Woodlouse Spider (Dysdera crocata)

Populations of woodlouse spiders are traditionally found in coastal states, but they are also becoming one of the more common spiders in Utah. Woodlouse spiders have sandy-colored abdomens, with a smooth, red cephalothorax and legs of a similar bright color. Keep an eye out for their bright red bodies if you have to go to your garage, basement, or attic in the middle of the night. They are one of the rare spider species that have only six eyes located above their dangerously large and sharp fangs. Woodlouse spiders only grow to roughly ½ an inch in length.

Woodlouse spiders…

• do not spin webs.
• are nocturnal hunters.
• prefer to hide and ambush prey.
• eat insects, house centipedes, lice, etc.
• only bite humans when provoked.
• do not produce venom that is harmful to humans, dogs, or cats.

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Other Spiders In Utah

While some spiders are much more dangerous than others, no spider bite should ever be taken lightly, especially if you are not an expert and are not 100% sure what type of spider bit you. Every one of the aforementioned spiders has the capability of causing serious infection or injury. There are, of course, other spider species that may be able to bite you, but the effects of their bites are virtually harmless.

There are thousands of species of ground spiders, none of which is known to cause serious harm. Orb-weaving spiders spin beautiful wheel-shaped webs, prefer to stay away from humans, and they are considered a non-threatening species; their bites are infrequent and do not contain a venom potent enough to seriously harm humans. Below are just a few more of the spiders commonly found in Utah that typically do not cause serious, or even moderate, harm to you and your loved ones.

• American Grass Spider - These spiders look like tiny wolf spiders, but they are not dangerous. They rarely grow over 1 inch long, and they attack their prey using their famous speed when they feel something crawling on their webs. Their bites cause minimal irritation to humans.

• Jumping Spider - Tiny, hairy, and almost cute, jumping spiders in Utah are not known to be harmful. They will not exceed 1 inch in length, and they are usually identified by mostly black bodies that have tiny colorful markings on their abdomens. Small bites can occur, but they are much more likely to jump, run, and hide when people get close.

• Cellar Spider - You have probably heard these critters be referred to as “daddy long-legs.” Cellar spiders actually seem to embrace the presence of humans, and they even benefit people by feeding on flies and other bugs. If they do attempt to bite, they will be unable to penetrate human flesh, making them truly harmless to people.

We hope you found this article as informative as we did. While spiders are common pests you will find all over Utah, another common pest that will cause damage to your lawn if not taken care of are lawn grubs. Check out our blog to learn how you can prevent lawn grubs from destroying your lawn.