- Spider mites cause injury as they feed, creating symptoms that can include, speckled bark, discolored leaves, and gray or bronze coloring. If an oak is extremely infested, these tiny insects can kill the tree. A sign that the mites are colonizing an oak is the presence of webbing. Spider mites can overwinter in trees and their eggs and young are sheltered in the webs. The pests activity increase in warmer weather and young are full grown in one week. Spider mites are difficult to get rid of, but most insecticidal sprays are able to stop an infestation.
- Itch mites are a fairly new insect discovery, first noted in 2004, according to University of Nebraska at Lincoln Extension. They are microscopic insects that will bite humans causing itching and irritation. The oak leaf gall mite feeds on the larva of midges. More than 16,000 mites can fall from a single infected leaf, according to UNL Extension. The mites can land on people causing painful, itching bites. Mites need about four hours on a human before they start biting.
- Erineum mites are microscopic, but under a lens they look like tiny carrots crawling around on the oak leaf. The leaf will get patches of velvety growth on the underside, where the mites live and eat. They are able to get the leaf to produce a growth called a gall for their protection The erineum galls look like pink bumps on the underside of the leaf, covered with the velvet-like growth. Erineum mites do no permanent damage to oaks. Their effect is primarily cosmetic and causes no lasting problems.