What to Know About Chiggers Bites, Symptoms and Treatment

Dr. Stephanie Lareau whizzed through the trees on her mountain bike in Roanoke, Va., one day in 2018. When she wanted to stop for water and a snack, she didn’t think much of plunking down in a pile of leaves near a reservoir to rest.

The next day, Dr. Lareau found a cluster of red bumps along the waistband of her shorts. Her back started to itch intensely.

Dr. Lareau, an emergency medicine physician at Carilion Franklin Memorial Hospital in Virginia, had seen these marks once or twice before on patients. She knew what had caused them. They were from chiggers, a species of tiny, reddish-brown mites able to leave bites that remain itchy for days or weeks.

What is a chigger bite?

Chiggers are common in humid regions, like Southern and Midwestern states. Chiggers inhabit grasses, decaying leaf matter and low shrubs near bodies of water. Historically, chigger season in the United States has been from late spring to early fall. But this period is likely to expand as temperatures rise across the country, said Loganathan Ponnusamy, a principal research scholar in the department of entomology and plant pathology at North Carolina State University. He said that scientists in North Carolina were finding chiggers earlier compared with previous years.

After chiggers hatch, the larvae can cling to clothing or skin. Once on the skin, they secrete an enzyme to digest skin cells, said Dr. Avinash Patil, an associate professor of emergency medicine at Stanford University who is trained in wilderness medicine. The enzyme causes an immune response that can lead to skin irritation, itchiness and red bumps.

Hot spots for bites include folds of skin near tight clothing such as waistbands, the top of sock lines and the area behind the knees. (If you see red bites clustered around your waistband, you can assume they’re from chiggers rather than mosquitoes or other bugs, Dr. Lareau said.)