There are several species of chiggers, but only two are troublesome. One, Eutrombicula alfreddugesi, inhabits disturbed grassy and weedy upland areas and may be encountered in overgrown briar patches and along the edges of wooded areas. The other, Eutrombicula splendens, prefers moist habitats such as swamps and bogs, rotten logs and stumps. Even within favorable habitats, distribution of chiggers often is spotty. Chiggers may be concentrated heavily in one spot while virtually absent nearby.

Chiggers of the genus Eutrombicula prefer birds, reptiles, rodents or other small mammals as hosts. Although chiggers readily bite people if given a chance, humans do not make good hosts. Chiggers often do not survive on humans more than 1 or 2 days, because of people’s adverse skin reactions and scratching.

Chiggers readily hitch rides on people who walk through infested vegetation. They grab onto shoes or clothing and typically explore a host for several hours before choosing a place to feed. Chigger bites are most common in areas where clothing is tight or where skin is thinnest. Bites are most common at sites around sock lines on the ankles where socks fit tightly, around the waist and near the groin. Bites also may occur in other areas, such as behind the knee and in forearm and underarm pits.

Contrary to common belief, chiggers do not burrow into a host’s skin or suck blood. They pierce the skin with their sharp mouthparts and inject a digestive enzyme, disintegrating skin cells for food. Itching usually begins within 3 to 6 hours after an initial bite, followed by development of reddish areas and sometimes clear pustules or bumps. Sometimes, as the skin becomes red and swollen, it may completely envelop the feeding chigger, making it appear that the chigger has burrowed into the host’s skin. Itching typically peaks 24 to 48 hours after chigger bites occur, but redness and itching may persist for a week or more for some people.