Pyemotes itch mites feeding on oak leaf gall maggots
This Can You Guess It?? photo appears in the September 2005 Nebline Newsletter.

Itch MitesUniversity of NebraskaĖLincoln (UNL) entomologists, are seeing signs of Pyemotes itch mites. The tiny mites may again be a problem in late summer and early fall.

Even though the numbers seem low now, populations of Pymotes itch mites can increase rapidly.

Each female can produce as many as 200-300 adult offspring. With a population doubling time of two days, Pyemotes mites can number in the millions quickly.

It could be similar to last yearís epidemic where thousands of Lincolnites reported suffering itchy red welts on their upper torsos, necks and arms. Most people were exposed to itch mites when spending leisure time outdoors or doing yard work. These mites dropped from oak leaves onto unsuspecting victims. UNL and KSU traced the problem to the itch mites known by the scientific name Pyemotes herfsi. This outbreak ó apparently the first widespread case in North America ó was noticed in Missouri and Texas, in addition to Nebraska and Kansas.

Leaf Edge Galls - Click for Larger ViewIf you have oak trees lining your street or in your yard, check trees for leaf edge galls (Photo right - click to enlarge). This includes pin oaks, red and black oaks. Burr oaks are not affected by this gall insect and wonít produce mites. Early reports suggest that, in some areas, galls are abundant again this year.

As things look right now, people spending time near leaf gall-infested oak trees will likely be exposed to mites from late August until frost or even later.

What you can do:

  • Wear an insect repellent. Check the label and follow directions for use.

  • Take a warm shower and lather well immediately after being near affected oak trees.

  • Donít handle grass clippings or leaves with bare hands, and plan to bathe soon after doing yard work.

  • After being outdoors, remove clothing immediately and donít wear it again until after itís laundered.

  • Use calamine lotion, benadryl or hydrocortisone cream to help reduce itching. Some sufferers have found benzocaine (cream, ointment or aerosol) to be helpful. Wash the site often with soap and use an appropriate antiseptic to keep affected areas clean and to promote healing. Donít scratch.

Unfortunately insecticide treatments of oak trees is of little value because mites are protected inside the leaf gall.

Whether the oak itch mite infestation turns out to be as bad as the one last year is yet to be known, but all the ingredients are present for history to repeat itself. Sources: Dave Keith, UNL and K-State Research & Extension News.

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