few fir species, all may be hosts. The damage they cause is unknown. Nalepella haarlovi Nalepella haarlovi is known from Denmark and Finland. It has been recorded infesting Picea sitchensis. They are one of the most economically important members of the genus. This species has four to eight generations per year. Nalepella halourga Nalepella halourga, commonly known as the spruce rust mite, is restricted to Picea (spruce). Their colour varies throughout the year; during the growing season, they are colourless to pale yellow, but in the fall they turn reddish-purple. They are found in Eastern North America. Nalepella longoctonema Nalepella longoctonema was first described in 1991 from two fir species in Oregon. They grow to 206 µm in length, and have been collected in large numbers on fir plantations. They are one of the most economically important members of the genus. Nalepella shevtchenkoi Nalepella shevtchenkoi lives around the bases of the host plant's needles, as well as on its stems. It is known from Abies (fir) and Picea (spruce) species. The species is considered one of the most damaging of the eriophyoid mites. It is found in parts of central and eastern Europe. Nalepella tsugifoliae The hemlock rust mite is reddish-orange in colour, and has relatively large eggs. They infest fir, hemlock, larch, and yew to high densities- there may be as many as 100 mites on one needle. Infested trees turn bluish, then yellow, before beginning to drop needles. They feed on both sides of the tree's needles. Notes References Pest arthropods Trombidiformes Trombidiformes genera