SPRUCE SPIDER MITE -Oligonychus ununguis or the Spruce spider mite causes damage that appears as tiny yellow dots on needles. The needles turn yellow and then brown. The damage is usually first observed on the older needles in the interior of the tree, eventually moving out the branches. When the mite population is very high, webbing may be noticed on the needles.  Lower branches may lose all of their needles, except new growth at the branch tips. Small trees may be killed and large trees may have some dieback.This spider mite prefers cooler temperatures and is active in the spring (March - June) and fall (September - November). Spider mites are very tiny, about 2 mm (can only be seen with some magnification, such as a hand lens). They have 8 legs and are yellowish green when young. When mature and fully fed they are grayish black, with a tan area behind the mouth parts. The eggs are spherical and reddish brown. There are several generations a year and eggs overwinter on the bark and needles. This mite prefers spruce, pine, hemlock, and arborvitae, but will attack other conifers. To check for mites, tap branches over white paper and look for the dark slow moving mites. Also look for predator mites which are fast moving, and tiny round, black ladybeetles that feed on the mites.If more than 10% of the tree is damaged and no predators are found, control may be needed.  Use a dormant oil in late winter to control overwintering eggs, if they are abundant. (They may be seen with a hand lens.) During the growing season, a summer rate of horticultural oil or insecticidal soap may be used.