Released: July 08, 2005

Evidence Suggests More Itch Mite Outbreaks This Year

MANHATTAN, Kan. – The tiny pests that caused big problems for Midwesterners last year may be back.

Entomologists from Kansas State University, along with colleagues from the University of Nebraska and Pittsburg (Kan.) State University, have found evidence of itch mites in Lincoln, Neb., and Manhattan, Kan.

“The mites gained notoriety last summer when people in communities throughout the Midwest – as far north as Omaha, east to St. Louis and south to Houston – suffered from their itching, but painful bites,” said K-State Research and Extension entomologist Alberto Broce.

This year the scientists have been surveying oak leaf galls, which are mainly found on the leaves of pin oak and red oak trees. Galls are small structures caused by the larvae of different types of insects – in this case, by the larvae of tiny insects called midges. The itch mites are attracted to the galls, where they feed on the midges growing inside.

Female mites are capable of producing about 200 offspring each, most of which are daughters, Broce explained. These daughters disperse with the wind in search of hosts, but sometimes land on people. When that happens, their attempts to feed result in bites that typically produce quarter-size reddened welts with a pimple in the center. The bites are usually found on the unsuspecting “victim’s” neck and shoulders and on areas of the torso where clothing fits loosely.

“Most of the midge larvae in the oak leaf galls found in Lincoln and Manhattan still appear to be too small to support a female mite to complete reproduction on a single midge larva. However, a mite detected in Manhattan had completed reproduction on an unusually large larva,” Broce said. “Considering that each female mite is capable of producing (hundreds of ) progeny in just seven days, it is not difficult to comprehend that mite population levels as they were found last year can be reached rather rapidly.”

Broce said the species of itch mite that sent some Midwesterners to their doctors in 2004 was introduced from Europe. At just 0.2 millimeters or 1/125 inch long, it is barely visible to the naked eye.

“They appear to need to be in contact for about four to five hours before they are a problem to people (for a bite to be manifested),” he said. “Because the bites do not get painful or itch for about 16 hours, many people do not know they’ve been bitten until the next day.

“Because of the four to five hour time frame, it’s a good idea to change clothing and take a hot, soapy shower after being outdoors in areas that may be infested with these mites. It’s also important to wash the clothing in a washing machine as soon as possible. That should help in reducing the number of bites.”

The scientists have found evidence that insect repellents based on DEET also can aid in reducing the bites.

To help with data he is compiling on itch mite distribution, Broce is interested in hearing from those who suspect they have been bitten by the mites. His contact information is 785-532-4745 or abroce@oznet.ksu.edu.

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Mary Lou Peter
mlpeter@oznet.ksu.edu
K-State Research& Extension News