There are several chemical and non-chemical remedies for controlling pests, particularly spider mites, on dwarf spruce trees, according to the Illinois Extension Service. However, the best way to avoid a spider mite infestation is to make sure the dwarf spruce is not stressed by overly wet conditions.
The first step is to make sure the problem is indeed spider mites. To check, simply hold a white piece of paper under a branch and shake the tree, says the Penn State Extension Service. The dark mites show up against the white background.
Next, you can either apply a chemical spray specifically for mites or a non-chemical remedy such as water or insecticidal oils. You can also use a biological control such as predatory mites or lacewings, according to the UC Davis Statewide Integrated Pest Management Program.