Chiggers, also known as harvest mites or red bugs, are not insects but are the parasitic larval stage of a tiny mite, an arachnid related to spiders and ticks. These microscopic pests cause intense, localized irritation by briefly attaching to the skin to feed. They do not burrow into the host. The resulting rash and severe itching are caused by an allergic reaction to their digestive enzymes, not the physical presence of the mite itself. Chiggers do not live on human hosts for long, often dropping off or being removed shortly after the biting process begins.
The Brief Feeding Period
The young chigger larvae are the only stage that feeds on vertebrates, including humans. Once a chigger finds a host, it seeks a protected area of skin, often where clothing is tight or the skin is thin, such as near waistbands or ankles. The mite pierces the skin and injects a potent salivary secretion containing digestive enzymes.
This enzyme breaks down skin cells, liquefying the tissue which the chigger then consumes. The body’s reaction to this foreign enzyme causes the tissue around the feeding site to harden, forming a protective feeding tube called a stylostome. The chigger remains attached to this structure, using it like a straw to draw up the dissolved tissue.
If left undisturbed, the larval mite feeds for two to four days before dropping off naturally. However, itching usually starts within three to six hours of attachment, alerting the host. Most people scratch the area long before the chigger completes its meal, dislodging or crushing the mite and ending the feeding process prematurely.
Treating the Irritation and Bites
Although the chigger is gone quickly, the intense skin reaction can linger for a week or more. The severe itching and red welts are a delayed allergic response to the digestive enzymes and the remnants of the stylostome left in the skin. Symptoms typically peak 24 to 48 hours after the bite occurs.
The goal of treating chigger bites is to manage discomfort and control the urge to scratch. Over-the-counter topical treatments are effective for alleviating symptoms. These include anti-itch creams containing hydrocortisone or soothing lotions like calamine.
Oral antihistamines, such as diphenhydramine, can reduce the body’s allergic response and provide relief from persistent itching, especially if sleep is disrupted. Applying a cool compress or taking a bath with colloidal oatmeal can help calm the inflamed skin. Avoid scratching the irritated skin, as breaking the skin barrier can introduce bacteria and lead to a secondary skin infection.
Immediate Removal and Prevention
If you have spent time in areas where chiggers thrive, such as tall grass or wooded areas, immediate action can prevent bites. The most effective step is to take a hot shower or bath as soon as possible after coming indoors. Scrub the skin vigorously with soap and a washcloth to physically dislodge any chiggers that may still be crawling or attaching.
All exposed clothing should be immediately removed and washed in hot water, then dried on high heat to kill any remaining mites. Chiggers can remain on clothing and reattach to a host if not properly laundered.
Protective measures should be implemented before venturing outdoors. Wearing long-sleeved shirts and long pants, and tucking pant legs into socks, creates a physical barrier against the mites. Applying an insect repellent containing DEET to exposed skin provides a chemical deterrent. For more robust protection, clothing can be treated with permethrin, an insecticide that kills chiggers on contact and remains effective through several washings.