Chiggers are the larvae of the harvest mite or red bug. The tiny larvae, measuring only about a third of a millimeter in length, inhabit grasses, weeds, shrubs, and brush, primarily in the southern United States (although they may be found as far north as Canada).
They most often attach themselves to human hosts at the ankles and legs, since these are the parts of the body most commonly exposed to the low-lying vegetation where chiggers dwell. However, chiggers generally prefer warm, moist places and so may lodge in the groin area, the armpits, the crook of the elbow, beneath the waistband of clothing, or any region where clothing is tight.
Unlike ticks, chiggers do not feed off blood, nor do they spread disease. Instead, they inject enzymes into the host. Skin at the site of the chigger bite may react in a variety of ways. An allergic reaction is common, producing extremely itchy red patches. Blisters and swelling may also appear.
While serious diseases due to chigger bites are not a threat in the United States, minor secondary infections may ensue, especially if the sufferer scratches the itchy bumps until sores occur, which can then be invaded by bacteria. Although itching and discomfort may persist for weeks, chigger bites cause no permanent ill effects.
What Causes Chiggers?
- Spending time in the woods or fields during the summer increases the risk of chigger bites.
Symptoms of Chigger Bites
- Extremely itchy, scattered, small red bumps. Chiggers may be visible in the center of unscratched bumps. Itching may persist for weeks
- Hives, blisters, swelling, or large red patches at the site of the bite(s)
Prevention of Chigger Bites
- Use an insect repellent during outdoor summer activities. Products containing diethyl toluamide (DEET) or permethrin are most effective. Follow directions on the container.
- When walking in the woods or fields, wear long-sleeved shirts and pants tucked into your socks or boots.
- Take a hot shower using plenty of soap once you come in from an area where chiggers might be. Wash clothes worn outside in hot water to kill any chiggers on the clothing.
- Whenever possible, do not walk through uncut fields, brush or overgrown areas and instead, walk in the center of mowed trails to avoid brushing up against vegetation where chiggers may be.
- Mow regularly and remove brush, wood and other debris to create a less favorable habitat for chiggers and their hosts.
Diagnosis of of Chigger Bites
- Diagnosis is determined by visual observation and generally does not require a doctor.
How to Treat Chigger Bites
- Try not to scratch chigger bites (scratching increases the risk of infection).
- Calamine lotion, cool compresses, menthol or pramoxine anti-itch cream may be soothing.
- At bedtime, take an antihistamine such as diphenhydramine, which can both relieve nighttime itching and help you sleep.
- Over-the-counter corticosteroid creams (hydrocortisone) may alleviate itching. More potent hydrocortisone creams are available by prescription.
- Your doctor may prescribe antibiotics to treat a secondary infection.
When to Call a Doctor
- Call a doctor if you suffer an allergic reaction (such as hives) to chigger bites or if over-the-counter treatments fail to relieve severe itching or if you develop a secondary bacterial infection.
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media