Ask the doctors: Strategies for keeping chiggers at bay

Dear Doctors: Any advice on controlling chiggers? When I work in the yard, they eat me alive unless I wear long pants. My wife does not garden and is rarely bitten. My son worked with me last weekend and said they don’t bother him. Why not? When we took a walk later, I got bitten again.

Dear Reader: “Chiggers” is the name given to an early life stage of trombiculidae, a species of parasitic mite so small, they’re almost invisible to the naked eye. Classified as arachnids, they are closely related to spiders and ticks. Chiggers are found in warm, humid environments throughout the world. They thrive in dense, shaded vegetation where there is abundant moisture. Here in the United States, they are most common in the southeast, south central and Midwestern states.

As part of their life cycle, adult females lay eggs in moist, decomposing organic matter. The larvae that emerge from those eggs climb the surrounding vegetation and wait to attach to a passing host. These include birds, rodents, reptiles and, as many gardeners and outdoor enthusiasts in chigger country can attest, humans. Differences in body chemistry and even the texture or color of someone’s clothing can play a role in whether they become a host. That may explain why your son seems not to be bothered by them.

It’s when the larvae find a host that the trouble begins. The hard red welts and maddening itch of a chigger bite are the body’s response to the chemicals the larval mites inject into the skin as they feed. The discomfort can last for two or more days. There are medications to ease the itching. Treatments can include calamine lotion, hydrocortisone creams, antihistamines or corticosteroids. The one bit of good news is that, unlike in some parts of Asia and the Pacific, chiggers in the U.S. do not carry or transmit diseases.

When it comes to preventing chigger bites, the most effective method is to create a physical barrier. Since they climb from below, long pants tucked into socks and closed shoes help reduce exposure. Long sleeves will help protect you from larvae you may brush against in tall grass or low-hanging leaves. It can also be helpful to treat shoes, socks and the cuffs of your pants with chemical deterrents, such as insect repellents that contain DEET or picaridin.

Even then, the battle against chiggers isn’t over. After spending time outdoors, it’s a good idea to shower promptly to wash away any larvae before they attach. Chiggers are vulnerable to heat, so you can also tumble clothes and footwear in a hot dryer to make sure none survive the trip into your home.

Unfortunately, it’s not possible to rid an outdoor area of chiggers. Guidance from the Centers for Disease Control and Prevention recommends that you protect yourself by making your yard less inviting. You can do this by clearing away leaf litter, keeping the grass trimmed and pulling weeds. Combine these steps with vigilant personal protection and a first-aid kit stocked with anti-itch medications, and you can reduce the risk of itchy misery during chigger season.

Send your questions to askthedoctors@mednet.ucla.edu.