The Spruce spider mite attacks predominately white, Colorado and Blue Spruce. It attacks the Conifer species making Cedars, Fir trees, Juniper, Larch and Pine susceptible as well. It is difficult to identify the spider mite as they are most often tiny and invisible to the eye. Holding a sheet of white paper under a branch, while shaking the limb will often times dislodge the mites, making them visible.
The mite originate in an egg which lays dormant during the winter under the bark, buds or at the base of the needles. In the spring (May-June), these eggs hatch into oval shaped larvae with three legs. These larvae feed off the needles and begin to turn from a pinkish color to green. They produce high amounts of offspring in a short period of time.
Needles will have a molted appearance.
Needles turn yellow and brown, they fall off prematurely.
Mites also spin webbing around the needles; the webbing can have a greyish appearance.
High amounts of webbing on the tree is one of the final stages and indicates a high mite population.
Mites do not thrive in high winds or humidity.
Removing the lower limbs increase light and air circulation reducing a favorable mite environment.
Smaller trees should be doused in water by a hose.
Removing the webbing and the nest can dislodge part of the mite population.
The spring and early summer is indicative of the high population growths of spider mite. If it is hot and dry ensure to water the entire tree frequently to change the environment to humid.
In severe cases pesticides may be necessary, however this is not recommended for residential areas due to the proximity of neighbors, children, dogs etc.