Poisonous hobo spiders are the most common spiders in northern Utah. They can reach 12 to 18 mm in length, have short hair and are brown. Females have larger abdomens than males, but both have chevron-shaped ("V"-like) markings. They also have two big palps, or genitalia, that are swollen on the males. Hobo spiders are not aggressive, but they can bite a human if trapped in clothing, in bedding or anywhere next to the skin. Although a hobo spider's bite is not fatal, it can cause local pain and tissue death.
The bite of a female black widow is traumatic and painful. Black widows are the most poisonous spiders in North America. Although male and juvenile black widows cannot harm humans, the venom of females has neurotoxins that can spread through the lymphatic system. Black widows have shiny black bodies and a red hourglass shape on their underside. They are also nocturnal, sleeping during the day. Black widows are not aggressive and bite only upon accidental contact with a person.
Northern Utah also is the habitat of beneficial spiders that pose no threat to humans. Camel spiders are nocturnal and common in southern Utah, but they can be found in the northern part of the state as well. Camel spiders are about 2 inches long and do not have venomous glands. However, their bites can be extremely painful. Crab spiders blend in with plants to hunt or ambush their prey. Some crab spiders even change color, depending on the color of their immediate environment.
To protect against spider bites, check your shoes, gloves and clothes before putting them on. Also, if you find yourself in a spider habitat do not walk barefoot. Don't try to catch a spider. If a spider bites you, try to remember what it looked like so you can identify it later. However, do not panic. Spider bites are rarely fatal.