By Judy Kunz, Colorado Master Gardener

Invisible to the naked eye, the eriophyid mite (pronounced eerio–fid) causes damage to ornamental trees and shrubs by piercing leaves, sucking out the juices with stylet-like mouthparts and injecting toxic chemicals that can cause deformed growth. Look for signs such as blistering or bronzing of leaves and/or stunted growth of twigs, leaves, buds, or flowers, along with gall-like deformities. While damage is mostly cosmetic, mites are also known to transmit plant viruses. Since diagnosis can be difficult, the best option is to send or bring a sample to the nearest CSU Extension Office.