Wolf spiders are often brown, but some have white on their backs. They are active hunters that feed mainly on insects and are generally found on the ground under stones, leaves or fallen tree bark and branches. Wolf spiders like to dig burrows on the ground, where they hide and wait for insects to pass nearby. Common species that live in Colorado include the giant wolf spider (Hogna carolinensis), with females measuring up to 1.4 inches in body length, and the burrowing wolf spider (Geolycosa), often mistaken for a tarantula.
Orb-weaving spiders use their round webs to capture insects, rather than hunting on the ground. Argiope, also known as the black and yellow garden spider, is a common species across North America, including Colorado. Females are silvery with dark and yellow markings, and measure about one inch in body length. Males are much smaller and less colorful. Argiope is often found in gardens from late summer to early fall.
Jumping spiders are part of the family Salticidae, with more than 5,000 spread around the world. Ground hunters that often show metallic patterns on their heads, they can jump short distances to capture their prey. Most species found in North America measure about one inch in body length. In Colorado, common genera include Terralonus, Poultonella, Peckhamia and Marpissa.
Part of the family Theraphosidae, tarantulas are nocturnal hunters, common in southeastern and southwestern areas of Colorado. Tarantulas have long lifespans, with females living more than 20 years. Tarantulas have urticating hairs on their backs and legs, which they use for defense. Although their bite is not dangerous to humans, the toxin produced in the urticating hairs can cause skin irritation. The genus Aphonopelma is common in Colorado, with females reaching up to 1.5 inches.