Chiggers
Trombicula spp., Trombiculidae, PROSTIGMATA


DESCRIPTION

Adult and Nymph -- Both stages are about 1.25 mm long, hairy, and usually brilliant red. Both have 4 pairs of legs.

Egg -- The minute, globular egg is light colored at first, changing to a darker color with age.

Larva -- Orange-yellow or light red, the hairy larva is about 0.16 mm in diameter. Larvae have 6 legs.


BIOLOGY

Distribution -- Chiggers are worldwide pests. They are most numerous in the coastal plains. They occur most frequently in pine straw, berry patches, in orchards, in woodlands, and along lake and stream margins.

Hosts -- The larvae of several species of chiggers attach themselves to the skin of man, domestic animals, wild animals, poultry, and birds. Nymphs and adults feed on insect eggs, small insects, and decaying organic matter.

Damage -- The fluid injected by a feeding larval chigger causes a reddish welt, swelling, itching, and sometimes a fever. The bites are primarily annoying, scratching by the host may break the skin and permit infection. No diseases are transmitted by chiggers in the United States.

Life History -- Chiggers pass through four developmental stages: egg, larva, nymph, and adult. Eggs hatch in about a week into the larval stage, which is six-legged. This is the parasitic stage which attaches itself to a vertebrate host until it is fully engorged with tissue fluids. After feeding, the larva drops off the host and molts to a nymphal stage, which in turn molts to an adult. Nymphs and adults are eight-legged and free-living. An entire life cycle requires about 50 days; there is usually only one generation per year in North Carolina. Little is known about the biology of the nymphs and adults or the overwintering stage.


CONTROL

Before entering areas where chiggers may exist, one may protect oneself by using a repellent. When applied to the skin and clothing, repellents do an effective job. For specific chemical controls, see the state extension service control recommendations.