Spruce spider mites are a member of the arachnid family and are distinguishable by their dark green appearance. Adults are approximately 0.5mm long. Spruce spider mites are tolerant of colder temperatures and tend to be inactive during the heat of the summer months. There are several treatment options for spider mites.
Unless you suspect the population of spruce spider mites is very large, the most cost-efficient treatment is to spray high-pressure water on the underside of the leaves or needles of the affected plant or tree. Repeated, daily sprays will dislodge mites missed on previous occasions.
The spraying of chemical insecticides or miticides is not recommended unless there is a large infestation of spider mites. Generally, sprays that contain clofentezine, bifenazate or Hexygon are most effective. Some insecticides and miticides are only available to licensed professionals.
Insecticidal or miticidal soaps are more readily available to the public. Soaps are most effective when used during summer months, the height of the plant's growth cycle.
Horticultural oils may also be applied during the summer months. For spruce spider mites, however, a dormant oil--comprised of petroleum products--is most effective. This is because the dormant oil kills the mites' eggs during the winter.
There are several natural predators of spider mites. These include the lacewing, the lady and rove beetles, minute pirate bugs and predatory mites. Predatory mites can be purchased. Never use insecticides if attempting biological control of spider mites.