What are itch mites?

Itch mites are microscopic insect-like creatures that cannot be seen by the naked eye. There are several different kinds of itch mites in the United States. One type, the oak leaf gall mite, is believed to be responsible for outbreaks of human bites in 2004 in Kansas, Missouri, Nebraska and Texas. The mite feeds on the larvae of a small fly (midge) which forms a brown and crusty shell on the edge of an oak leaf (known as a gall).

Can people be bitten by itch mites?

Yes. Although the oak leaf gall mite feeds on midge larvae, they can accidentally bite people when looking for food. Mites usually need about four hours on your body before they bite. Once the mite’s regular food source is gone from the leaves, usually in late summer, the mites drop from the trees. Oak leaf gall mites are so small that they can float on the wind, and pass through window or door screens and loosely-woven clothing.

How will I know if I have been bitten?

You may develop red welts that look like chigger bites on your neck, face, arms and upper body. These bites are not usually on legs where chigger bites may be found. The itch mite welts form into a pimple-like lesion after about 12 hours. The bites are very itchy and can be present for up to two weeks.

What should I do if I think I’ve been bitten?

The most important thing is not to scratch the bites, since scratching can lead to an infection. Try over-the-counter topical anti-itch creams and oral anti-histamines to control itching. If the itching is intense, or you develop a skin infection, you should contact your health care provider.

• If you see brown and crusty edges on oak tree leaves, be aware that mite activity is possible. Don’t sit under oak trees or on nearby lawns.
• If you are in an area where itch mite associated rashes are occurring, or nearby oak trees have brown and crusty edges:
  • When weather permits, keep windows shut from August through October when “mite-showers” can occur.
  • Remove clothing items each day and launder them. Take a warm, soapy shower after coming indoors, especially after gardening, raking leaves or performing other outdoor activities.

Can I use DEET or other insect repellent?

Since the mites only bite people when they accidentally fall on them, DEET and other insect repellents may not work. However, to prevent being bitten by mosquitoes, which can carry West Nile virus, you should use insect repellents with DEET.

Can itch mites live in my home?

No, in order to survive, itch mites need to feed on insect larvae, which are usually found on the inside of tree leaves.

If the mites come from oak trees, should the trees be sprayed or removed?

No. Since mites feed on insect larvae that are inside the edge of leaves, chemical sprays are not effective. Removal of trees is not necessary because these mites are not likely to be a problem every year.

An opened “leaf edge” gall revealing dead midge larvae and itch mite females with enlarged abdomens.		Itch mite lesions on an arm.

Both photos courtesy of University of Nebraska Entomology Department.

References

Pyemotes Itch Mites - University of Nebraska–Lincoln

They're Back – Itch Mites on the Increase - University of Nebraska–Lincoln

Outbreak of Pruritic Rashes Associated with Mites --- Kansas, 2004 - CDC

For more information, contact the Illinois Department of Public Health, Division of Environmental Health, 525 W. Jefferson St., Springfield, IL 62761, 217-782-5830, TTY (hearing-impaired use only) 800-547-0466.