Utah State University Extension
Spiders are arachnids, a group that includes other 8-legged arthropods like ticks, mites, sun spiders, scorpions, and harvestmen (daddy longlegs). There are approximately 621 species of spiders known to occur in Utah (Allred and Kaston, 1983). Spiders are beneficial predators and the majority of them are harmless to humans.
Davis, Ryan S. and Ramirez, Ricardo A., "Spiders" (2013). All Current Publications. Paper 960.