Pest description and crop damage The adult is a small greenish to brown mite. Their feeding causes small whitish, yellowish, or bronze streaks that look like pin scratches on the upper leaf surface. Heavy infestations can cause premature leaf drop. Damage is common throughout the Willamette Valley of Oregon.
Scouting and thresholds Observe the leaves for mites and webbing and check for the number of pest and predator mites. Sufficient biological control usually is achieved by midsummer.
For more information
PNW Nursery IPM: Boxwood spider mite (http://oregonstate.edu/dept/nurspest/boxwood_spider_mite.htm)