Chiggers are the parasitic larval stage of a mite belonging to the Trombiculidae family, making them closely related to ticks and spiders. These nearly microscopic arachnids cause intensely itchy bites. The larvae attach to skin and inject a digestive enzyme to liquefy skin cells, which they then consume. The resulting red welts and irritation are a reaction to this enzyme, not burrowing into the skin.
Identifying the Chigger
Only the larval stage of the mite, often called “red bugs,” is parasitic and causes irritating bites. These larvae are tiny, measuring less than 1/150 of an inch in diameter, and are typically yellowish or light red. Chiggers prefer environments with high humidity, thriving in tall grasses, dense weeds, brushy areas, and along the edges of wooded areas.
The larvae position themselves on vegetation close to the ground, usually less than a foot high, waiting for a host. Once attached to clothing or shoes, they migrate in search of a suitable feeding site where the skin is thin or constricted, such as around the ankles or waistline. They remain attached for a few days to feed before dropping off.
Lethal High Temperatures
High heat generated by household appliances is the most reliable method for quickly eliminating chiggers from clothing. Chiggers actively avoid temperatures above 99°F (37°C), and temperatures around 120°F (49°C) are lethal to the mites. This thermal vulnerability provides an effective strategy for decontamination after exposure.
The most effective tool for destroying chiggers on clothing is the clothes dryer, running on a high-heat cycle. The sustained, high temperatures quickly kill any mites clinging to the fabric fibers. While a hot water wash cycle will also work, immediately transferring the exposed clothing to a high-heat dryer cycle ensures their rapid demise.
Surviving the Cold
Chiggers are highly dependent on warm temperatures for activity and survival; cold conditions force them into a dormant state or cause death. Larval chiggers become completely inactive when ground temperatures drop below 60°F (16°C), effectively ending the chigger season. The adult stage, which does not bite, is capable of overwintering by burrowing beneath the soil or in sheltered leaf litter.
A sustained ground temperature below 42°F (6°C) is lethal to the larval, egg, and nymph stages. While adult chiggers can survive a typical winter by entering a protected state, extended periods of hard freezing temperatures significantly reduce the population that emerges in the spring. Chigger activity is limited to the warmer months, typically from late spring through early fall.
Eradicating Chiggers from Clothing and Skin
Immediate action upon returning from a chigger-infested area is necessary to prevent the mites from attaching and feeding. The first step is to remove all worn clothing immediately and place it directly into a high-heat dryer cycle before washing. This dry heat process ensures that any attached chiggers are killed before they can dislodge elsewhere.
Next, a warm, soapy shower is essential to dislodge any larvae that may have transferred to the skin. Vigorously scrubbing the skin with a washcloth and soap helps to physically remove the mites before they attach and begin feeding. Using an insect repellent containing DEET on exposed skin or treating clothing with permethrin before exposure offers an effective preventive barrier.