Nalepella, the rust mites, is a genus of very small Trombidiform mites in the family Phytoptidae.[2][3] They are commonly found on a variety of conifers, including hemlock, spruce, balsam fir, and pine.[3][4][5][6] They sometimes infest Christmas trees in nurseries.[3][5]Nalepella mites are vagrants, meaning they circulate around the tree; females overwinter in bark cracks.[5][7] Infested spruce emit a characteristic odour.[8]
^Baker, Whiteford L. (Whiteford Lee) (1972). Eastern forest insects. National Agricultural Library U. S. Department of Agriculture. Washington : U.S. Dept. of Agriculture, Forest Service ; for sale by the Supt. of Docs., U.S. G.P.O.