Oak leaf itch mites could persist ‘for several more weeks’ (+video)

Master gardener Janie Chisholm had been itching for three weeks before she found out that the welts on her neck, torso and the insides of her arms were from oak leaf itch mites that had fallen on her unseen and unfelt from the leaves of oak and pin oak trees.

But she still had to mow under the oak tree in her yard and under the oak tree that casts shade into her yard from her neighbor’s.

“I really hurried past my tree, and then her tree … because I knew by then where the bites were coming from,” Chisholm said Wednesday.

She’d also found out that taking a shower within three or four hours of being under oak trees could mitigate the mites’ bite. But there was a total eclipse of the moon to be seen Sunday night, so she skipped the shower after mowing the lawn.

“I started to feel them toward the end of the eclipse,” Chisholm said. “It was toward 11 when I came in. Then Monday morning they were really bad.”

Chisholm is one of many people in the Wichita area who have been scratching their heads as well as their arms as to the cause of the mysterious, itchy bites on their bodies. Most years, the oak leaf itch mite is not an issue. The mites caused some trouble last year in Wichita, and they’ve exploded this year.

“We’ve had lots of calls,” Matthew McKernan, a horticulture extension agent for Sedgwick County, said Tuesday.

The oak leaf itch mite – Pyemotes herfsi, first identified just a decade ago – hangs around gall formations established on tree leaves by insects such as midges. The midges will lay eggs in the gall formations or the abnormal growth on the leaves that looks like bumps or blisters.

“This year we have had a spike in the number of these gall formations,” said Dennis Patton, horticulture agent in Johnson County.

The mites, meanwhile, feed on the insects in these gall formations. The microscopic mites, entomologists say, hold down the number of midge larvae. And because the mites are protected inside the galls, spraying trees with a pesticide won’t get rid of them.

With the coming of cooler temperatures and shorter days, the mites have been exiting the galls, Patton said. When the mites hatch, in just one day a tree could shed more than 370,000, entomologists say.

Anyone under or near one of these trees, or even downwind from them, likely has been visited by the mites, which are almost microscopic at just 0.2 millimeters in size.

The bites are usually found where clothing is loose, and more on the upper body because they fall out of trees. Routinely their bites will leave persistently itchy red marks, sometimes with a fluid-filled center. Products that can ease the itching include cortisone cream, an antihistamine and Calamine lotion.

Insect repellants don’t help, McKernan said. The extension office in Wichita is advising people to reduce the time they spend under pin oaks and red oaks, which have had more of the galls; wearing gloves when working with leaf debris; and showering or bathing after working in the garden and washing the clothes they were wearing outside.

The bites, while annoying, usually are not considered dangerous. The bigger risk is secondary infection caused by scratching, something both adults and children can find difficult to resist.

After weeks of suffering, Chisholm finally pulled out an old bottle of Benadryl gel and put that on her latest mite bites. “And I’m just amazed, because I’m still not itching,” she said Tuesday.

Two hard freezes, Patton said, should bring an end to the oak leaf itch mite invasion of 2015.

“It’s something we’ll see for several more weeks, I believe,” McKernan said.

This story was originally published September 30, 2015 at 7:40 PM with the headline "Oak leaf itch mites could persist ‘for several more weeks’ (+video)."