Many members of the Chicagoland area have been afflicted with painfully itchy rashes caused by a surge in oak leaf itch mites following the end of the cicada season. Mites are not thought to cause disease; however, excessive scratching can lead to bacterial infections.

“Mite bites are quite painful and appear as swollen, red bumps with small blisters in the center, showing up 10 to 16 hours after being bitten,” LT nurse Laura Byrne said. “They cause itching and skin irritation.” 

The bites resemble chigger bites but are more likely to be found on the neck, face, arms, and upper body than the legs where chigger bites tend to occur. Mite bites can be present for up to two weeks, whereas bites from better known insects like mosquitoes last only a few days. Oak mites, which are nearly invisible to the naked eye, feed on the larvae of midges, which are a type of small fly that often live in cicada nests. Thus, they experienced a surge in population during the 2024 Cicada Double Brood. 

In late summer, with their food sources gone, oak leaf itch mites tend to drop from oak trees and accidentally bite humans. A single large oak tree can drop up to 400,000 mites in a day. However, humans can still get bitten even when not under oak trees because mites can be blown by the wind or transfer from pet fur. For this reason, insect repellent may not be effective towards mites, the Illinois Department of Public Health website said. When mite activity is high, it is recommended to take preventative measures like not sitting near oak trees, wearing protective clothing like longer sleeves, pants, and hats, and keeping up proper hygiene after going outside. Over-the-counter anti-itch creams can help to alleviate scratching. 

“I just moved here from Texas, so when I was first bit I thought that the mosquitoes in Illinois were a lot worse because of how long the bites lasted,” Grace Rhoten ‘25 said. “I heard a lot of people talking about how there were mites from the cicadas, which made me realize I had the mite bites.”

The 2024 Cicada Double Brood was a rare convergence of Brood XIX which occurs every 13 years and Brood XIII every 17 years. This event will not reoccur for another 221 years. Cicadas emerged in June as they do annually, but in much larger numbers, before gradually disappearing underground during July and Aug..

Periodical cicadas are difficult to study because people will only witness a few cicada life cycles in their lifetime, so not much is known about the long-term effect on the ecosystem. What is known is that they temporarily disrupt the food chain because they become a food source for many other animals. Food chain disruptions can result in population surges in certain species, such as oak leaf itch mites.