Oak Gall Mites

Habitat

• The oak gall mite (Pyemotes herfsi) is minute and barely visible to the naked eye, measuring approximately 1/100th of an inch. The mite is attracted to oak galls, a structure caused by another insect feeding on the leaves of an oak tree. These galls are actually a part of the leaf, as the initial insect injects a liquid into the leaf that causes the cells to mutate and form the gall -- a protective object that serves as both shelter and a food source for the developing larvae of the first insect.

Significance

• The oak gall mite also inhabits the gall to feed on the host insect. Essentially, the oak gall mite is a parasite on a parasite. When there are not enough galls or larvae on the tree to satisfy the hunger of the oak gall mite, it will attach itself to a human who may not be able to view the mite, but can normally feel the pest moving about their skin as it seeks to make a home in hair follicles or pores.

Human Infestation

• The mite injects human skin with saliva, a technique that serves to desensitize the skin and allow the mite unlimited feeding time as it sucks lymph fluid from the body. The feeding normally is not noticed for several hours until an itching sensation and a welt or rash develops on the skin. The mites drop off soon after feeding. While the oak gall mite typically carries no disease, the reaction of the immune system to this bite varies in individuals.

Prevention/Solution

• Those who work in or nearby oak trees can protect themselves from the irritation caused by the oak gall mite, simply by wearing long-sleeved clothing and hats or by using insect repellent. A strong shower -- with soap -- is also helpful in removing the mite from skin. Immediately wash clothing because the mite can survive in fabric for several days. Unfortunately, the tiny mites are also capable of floating in the wind through window and door screens.