Eggs of arborvitae spider mite lack a stipe and give the appearance of having two parts. They have a somewhat flattened base and are crimped to a conical top, resulting in a ridged or scalloped edge. All Platytetranychus mites, including arborvitae spider mite and honeylocust spider mite, overwinter as orange to red females in protected areas around bud scales and in bark crevices. In spring, they begin to deposit eggs which hatch into six-legged larvae. A chrysalis stage, during which the exoskeleton is shed, occurs between each active stage.
All active stages feed.
The arborvitae spider mite can be found on arborvitae from May through November. The occurrence on juniper is more constant throughout the growing season. All spider mites feed by inserting needlelike mouthparts into host tissue and withdrawing cell contents. Feeding damage generally appears as chlorosis, browning, or bronzing, with subsequent defoliation when damage is severe. Heavy infestations of this mite can cause serious fall and winter browning of foliage.