Spider Mites are one of the most damaging pests to most varieties of Spruce, Arborvitae, and other conifers. Mites suck sap from individual needles, causing a ‘stippled’ appearance as the chlorophyll disappears. The damaged inner needles begin to yellow and eventually turn brown and fall from the tree. It is important to note that Mites will not attack first-year candle growth, but they will attack that new growth the following year.

Affected plants that were originally full, thick conifers (often planted as natural privacy screens) will begin to thin out to the point that you can see right through them, no longer providing the intended privacy. These plants then eventually die.

Mites enjoy the cool, damp weather that Illinois provides in spring and fall. Left unchecked, they build up in tremendous numbers, multiplying by the thousands every 10 to 17 days!

It is important to note that Mites are in their own category and are NOT considered insects! Therefore, traditional insecticides will not kill and control them. Mites require specialized products as a means of control. Another complication of treatment is that Mites tend to rapidly build up tolerances to Miticides that are used repeatedly. Because of this, most of the Miticides used during the past 10-30 years by homeowners and tree care companies are no longer effective.

To control Mites effectively, select a tree company that offers updated Miticide products and rotates their use to help prevent immunity.