Spider mites are common evergreen pests. One spider mite is particularly damaging to evergreen trees and shrubs. The spruce spider mite is often found on pines, juniper, arborvitae and cedar, causing damage to the evergreen plant while feeding on its leaves. Spider mites are often quite difficult to control when large populations are present.
The spruce spider mite is active during periods of cool weather and disappears during the hot summer months. This spider mite affects over 40 different species of evergreens, states the University of Kentucky. Spider mites are members of the same family as spiders and ticks, and have eight legs. These pests feeds on evergreen shrubs with piercing mouthparts, sucking sap from evergreen leaves and needles. Evergreens damaged by the spruce spider mite often do not show damage until the following summer with the onset of hot, dry weather.
Evergreen shrubs infested with the spruce spider mite often have white-colored specks of flecks in their leaves or needles, which is known as stippling. Heavy or prolonged feeding also causes browning of leaves, leaf or needle yellowing and premature leaf drop. The spruce spider mite often leaves a fine silk webbing on the host tree and egg shells are often visible on the tree, as well. Heavy or repeated spruce spider mite infestations can kill evergreen shrubs and trees.
Examine your evergreen trees and shrubs for signs of spruce spider mite damage. The leaves and needles will have a speckled appearance if mites are present, or may have webbing on the leaves. Shaking the limbs of your shrub or tree over a white sheet of paper often reveals spider mites as they fall from the tree. Spruce spider mites are typically dark brown or dark green in color, and leave a green or brown stain when squashed.
Evergreen shrubs suffering from infestations of the spruce spider mite usually require chemical controls to prevent severe infestation and damage to the host tree. There are miticides available at local garden centers designed for the treatment of spider mites. Cover the shrub thoroughly for best results, as these products work on contact to kill spider mites. You can also use predatory insects that feed on the spruce spider mite, such as lady beetles and parasitic wasps. If large numbers of predatory insects are present on your evergreen shrub, chemical controls are not recommended.