Chiggers

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Chiggers

What are chiggers and where are they found?

A “chigger" is a type of mite that feeds on birds, reptiles, amphibians, mammals, and humans. There are about 20 species of chigger mites around the world that are known to feed on humans, and of those, only two species are known to bite humans in the United States. Chiggers live in a range of habitats from meadows to swampy areas, but are most commonly found in grassy or scrubby vegetation, shaded areas, leaf litter, rotten logs, and stumps.  ​​

What do chiggers look like?

Chiggers are the larval stage of a mite in the family Trombiculidae. The chigger mite has a lifecycle similar to a tick.  Adult females lay eggs, which hatch into six-legged larvae. These 6-legged larvae are the only life stage that feeds on humans.  The larvae develop into 8-legged nymphs and then into adults after feeding.  Chigger larvae are extremely small (1/100 to 1/120 inch) and will appear red, orange, or yellow through a magnifying glass.  The larvae are active from early spring through late fall. Chigger nymphs and adults do not bite humans; they feed on small, soil-dwelling insects and insect eggs.  Adult chigger mites are figure-eight shaped and covered in dense red, yellow, or orange hairs. Adults are active in the fall, overwinter in the soil, and lay eggs early in the spring.  

How do chiggers bite?

Contrary to popular belief, chiggers do not burrow into the skin or suck blood.  Using large claws located near their mouths, chigger larvae quickly attach to any exposed skin that contacts infested grass or soil in vegetated areas. The larvae then cut the skin with blade-like mouthparts called chelicerae and inject an enzyme into the cut that digests the skin at the bite site.  This makes the cells around the bite site harden into a “drinking straw”, which the chigger uses to suck up the liquefied tissue. Chigger larvae will feed for several hours and then drop off the host to find a sheltered place to digest the meal. The bite site stays irritated by the digestive enzymes long after the chigger finishes feeding and detaches​.

Can chigger bites make me sick?

In the United States, chiggers do not transmit diseases, but feeding larvae can cause extreme skin irritation. In parts of Southeast Asia and the islands of the southwest Pacific, chiggers transmit scrub typhus, a potentially life-threatening bacterial disease in humans. Scrub typhus can cause welts, swelling, and fever within several hours of chigger exposure.  Seek medical attention if you think you may have been exposed to scrub typhus.

 ​​​What are the signs and symptoms of chigger bites?

Chiggers prefer to bite skin where clothing fits tightly, such as around waistlines, sock lines, and behind the knees.  Skin begins to itch approximately 1-3​ hours after being bitten by chigger larvae. The skin will eventually develop itchy, red or puss-filled bumps at the site of attachment which can be extremely irritating. The itching persists for up to a week and complete healing of the skin lesions can take up to 2 weeks.

How do I prevent chigger bites?

The best defense against chiggers is to avoid them. Chigger infestations are less common in maintained lawns and landscaped environments.  Do not sit, lay down, or walk barefoot in chigger habitat. Cover your skin to limit access to your feet, ankles, and legs. Wear loose-fitting, tightly-woven fabrics to prevent chiggers from moving through clothing.  ​

Use the DOD Insect Repellent System for maximum protection from chigger bites​​​. It incorporates insect repellent on the uniform, DEET, picaridin, or IR3535 repellent on exposed skin, a properly worn uniform, and sleeping inside a insecticide-treated bed net.​

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