Chiggers, also known as "red bugs", are the tiny orange, yellow, or red parasitic larvae of mites in the family Trombiculidae. The feeding behavior of these larvae can cause intense itching and small, reddish welts on the skin of humans. Chiggers feed on a range of hosts, including small mammals and preferentially birds, reptiles and amphibians. Humans are an accidental host. Chiggers that attach to humans are usually brushed off and die within hours.
Chiggers ( Trombicula alfreddugesi ) are about 1/150" in length. In order to see chigger larvae, you must use a magnifying glass. They are born red or orange, but once they have fed on the skin cells of their host, they change to a yellowish color. They have six legs and a hairy body.
Adult chiggers can over-winter below the soil or in other protected places. In the spring, females lay up to 15 eggs per day in vegetation or soil. Eggs hatch into six-legged larvae. After they hatch, chigger larvae climb up vegetation to seek a host. Once they find a suitable host, they attach to delicate areas of the skin and feed from one to several days. When they are completely engorged, they drop off the host and transform into eight-legged nymphs, which then mature into adults. The life cycle is generally complete within 50-70 days. In northern states, only about two to three generations develop each year.
Chiggers are usually encountered in the late spring and summertime. They can be found in overgrown areas, lawns, leaf litter, shrubbery, and anywhere that is damp and shaded. Once the chigger larvae have found their way onto a suitable host, they proceed to areas of the body where clothing fits tightly over the skin (e.g., the beltline, waistline, undergarments, and socks) or where the skin is delicate and/or wrinkled (e.g., ankles, armpits, back of the knees, front of the elbow, or in the pubic region).
Contrary to popular belief, chiggers do not burrow under the skin, nor do they suck blood. Larvae pierce the skin with their mouthparts and inject a salivary secretion containing powerful digestive enzymes that attack the surrounding skin cells and cause the cell walls to break down. Essentially, the skin becomes digested and is subsequently sucked up by the chigger. The other function of the digestive fluid is to cause hardening of the surrounding tissues, forming a straw-like feeding tube called the "stylosome". The bite sites generally erupt into a red welt with a hard, white central area. People who are bitten by chiggers usually experience intense itching at the bite site within several hours. These welts itch persistently for up to a week or more.
People who do not remove the chiggers promptly may still suffer from bites and are advised not to scratch the welts excessively as this may lead to secondary infection. Temporary relief of itching can be achieved by applying benzocaine, hydrocortisone, calamine lotion, or other topical anti-itch creams that your pharmacist or physician can recommend.
People who know they have been in chigger-infested areas should immediately launder their clothes in hot water (125oF) for at least 30 minutes. As soon as possible, they should take a hot bath or shower and lather themselves with soap several times. Chiggers and their itchy bites can also be avoided by wearing loose clothing, using insect repellant and avoiding their preferred habitat. Clearing your yard of potential chigger habitat can help eliminate chiggers.
To assess whether you have chiggers in your yard, place a piece of black cardboard upright in a section of the lawn. If chiggers are present in the area they will move very rapidly toward the new object in their area. They will appear as pinkish dots moving across the cardboard. You may then want to consider possible extermination methods.
To determine the best course of action for removal of chiggers on your property, contact a licensed pest control operator. He or she will be able to advise you as to the best and most effective method for removal of the chigger populations.