How long should you watch for mite bites in the Chicago area? – NBC Chicago

How long should Chicago area residents watch for mite bites associated with the area's historic cicada invasion?

In recent weeks, there has been an increase in seemingly mysterious insect bites throughout the Chicago area.

The increase in reports of itchy bites and rashes is likely linked to an increase in oak leaf itch mite populations in cicada egg nests laid during the historic 2024 emergence, experts say.

What you should know:

What is the oak leaf itch mite?

According to researchers at Pennsylvania State University, the mite first appeared in Kansas in the United States in the fall of 2004, when around 19,000 cases were reported. Since then, it has spread to Illinois, Nebraska, Ohio, Oklahoma, Missouri and other countries.

“This mite can cause an itchy rash that is often erythematous (a reddening of the skin) and papular (with small, raised, pimple-like bumps),” the university explained. “Although they have been reported to feed on many different insects, it is only when they have become very numerous and their current food source has been destroyed that they seek out alternative hosts and accidentally bite humans.”

The mites are described as reddish-brown in color, with shiny exoskeletons and four pairs of legs.

“Studies have shown that as many as 370,000 mites can fall from trees per day,” Penn State reported. “They are also easily carried by the wind and can potentially penetrate window screens, thus biting people who are not often outdoors. However, most bites occur during yard work, especially among those who rake up infested swamp oak leaves in the fall.”

What is the connection between insect bites and cicadas?

According to cicada expert Dr. Gene Kritsky of Mount St. Joseph University, after a cicada emerges, a particular mite known as the “oak leaf itch mite” can be observed in large numbers.

Kritsky noted that in 2007, “people in Chicago who had oak trees in their yards began complaining about stings after the cicadas showed up.”

“It turns out that the oak itch mite was found in the egg nests of Brood XIII cicadas,” Kritsky told NBC Chicago.

This same offspring was one of the two who appeared in Illinois during the historic 2024 event that Kritsky described as “biblical.”

But while the periodic emergence of cicadas appears to have declined significantly, giving way to the annual “dog day cicadas” that are now appearing throughout the region, the eggs laid months earlier are now leading to an increase in mites.

“This is kind of the last hurrah call of the cicadas that cause this itchy itch,” Kritsky said.

Those who experienced large numbers of cicadas during this emergence will likely still have thousands of eggs left to hatch.

Hatching occurs between six and ten weeks after the eggs are laid.

“The eggs hatch six to seven weeks [after they are laid]the nymphs fall to the ground and sink into the soil, and the cycle begins again,” the Natural History Museum reported.

In areas of heavy infestation, up to 40,000 eggs could be lying dormant on trees, Kritsky added.

How long should you watch for mites?

According to researchers, the bites occur most frequently in late summer and fall, when the mite population is at its highest.

“People should avoid sitting under the trees until the eggs hatch in mid-August,” Kritsky said.

But as August draws to a close, the mites could continue to wreak havoc into the fall.

What happens if you get bitten by an oak leaf itch mite?

The Illinois State Department of Health noted that mites typically spend about four hours on a person's body before biting.

“These bites cause a mild rash that causes itching and discomfort,” said Dr. Ben Flagel, chief of the emergency department at Endeavor Health Swedish Hospital.

How to tell if you have been bitten by an oak leaf mite

According to the IDPH, the bites resemble “red welts on the neck, face, arms and torso that look like bites from grass mites.”

“These bites do not usually occur on the legs, where grass mites usually bite,” the IDPH reported. “The welts from the itch mites form a pimple-like lesion after about 12 hours. The bites are very itchy and can last up to two weeks.”

Can mite bites be treated or prevented?

According to health authorities, the most important thing is to avoid itching and scratching the bites.

The IDPH recommends over-the-counter anti-itch creams or oral antihistamines that can help relieve itching, but if the itching becomes too severe or you feel like an infection has developed, officials advise contacting a doctor.

“The concern is that if the itching is too severe, the skin can be torn and a bacterial infection can occur,” Flagel said.

Controlling oak leaf mites can be difficult because many sprays do not specifically target the parts of the tree where the mites develop.

“The effectiveness of DEET (a mosquito and tick repellent) is mixed,” Penn State reported. “People can best protect themselves by minimizing time spent under infested trees and by immediately removing clothing, washing and then showering.”

The IDPH recommends the following tips to prevent stings:

• If you see brown and crusty edges on oak leaves, be aware that mite activity is possible. Do not sit under oak trees or on nearby lawns.
• If you are in an area where rashes caused by scabies mites are occurring, or if nearby oak trees have brown and crusty edges:
  • If the weather is good, keep the windows closed from August to October, as there can be heavy showers of mites during this time.
  • Remove and wash your clothes every day. Take a warm shower with soap after entering the house, especially after gardening, raking leaves, or other outdoor activities.