Twenty-three species of spider mites (Tetranychidae) are recognized for Utah and Idaho; three of these are described as new: Bryobia neoribis, Pseudobryobia knowltoni, and Schizotetranychus agropyron. Eleven species of Tenuipalpidae are recorded.
Tuttle, Donald M. and Baker, Edward W.
"New records and species of Tetranychidae and Tenuipalpidae (Acarina) from Utah and Idaho,"
Great Basin Naturalist: Vol. 36
, Article 3.
Available at: http://scholarsarchive.byu.edu/gbn/vol36/iss1/3