Seems to love peas, that was where it was found, in Jackson Hole, WY.
Appears to be about 2″ long.
Prominent yellow ‘slashes’ along the side.
‘Tufts’, not spikes, along the body, which seems to be predominantly brown.
Your caterpillar is probably the salt marsh caterpillar. Without a clearer photo, especially of the head, we can not be positive. These caterpillars are highly variable, they can be a challenge to ID.
The caterpillars do vary a lot in color and look like several fall fuzzy caterpillars, but if it has a black face then you know it is a salt marsh. If it has a yellowish face then it is the other fuzzy caterpillar the Virginian Tiger moth.
They turn into white moths with black dots on the wings and with orange abdomens. The male moths have colored hind wings while the female hind wings are usually white.
The caterpillars come in various colors – whitish to brown to black, with long bristly hairs.
This caterpillar is found in weedy roadsides, prairie grasslands, meadows, and such areas. Larvae feed on many mostly weedy plants including pigweed, ground cherry and mallow, plus crops such as alfalfa, asparagus, bean, beet, cabbage, carrot, celery, clover, corn, cotton, lettuce, onion, pea, potato, soybean, tobacco, tomato, and turnip.
They are not considered a pest.
These insects are found all over North America.
The moths come to lights at night.
This caterpillar will not sting or cause a rash.