Chigger

Definition

The parasitic larval stage of trombiculid mites (family Trombiculidae), tiny arachnids that attach to vertebrate skin and feed on digested tissue, causing intense itching and the dermatological condition trombiculosis. Despite common misconception, chiggers do not burrow into skin or suck blood; instead they inject digestive enzymes that liquefy epidermal cells, which they then ingest. The six-legged larvae are bright orange-red, nearly microscopic (≈0.4 mm), and are often encountered in grassy or brushy habitats. Adults are free-living predators, not parasites.

Etymology

Origin uncertain; possibly from British dialect chig, chigge, or alteration of jigger (a flea or mite), with early 20th-century American usage solidifying the form.

Example

Field biologists working in tall grass often tape their pant cuffs to prevent chiggers from accessing skin; the larvae typically attach at clothing constriction points such as sock lines or waistbands.

Synonyms

• harvest mite
• red bug
• berry bug
• scrub-itch mite

Related Terms

• trombiculosis
• mite
• Trombiculidae
• Acari
• Ectoparasite
• Vector

Usage Notes

In North American vernacular, "chigger" refers specifically to the larval stage (e.g., Trombicula alfreddugesi), not the free-living nymph or adult. The term is sometimes misapplied to other parasitic larvae, including certain dipteran maggots (jiggers, Tunga penetrans), which are unrelated. Specialists distinguish chiggers from ticks (Ixodida) despite both being parasitiform arachnids—chiggers are far smaller, do not transmit systemic pathogens to humans in most regions, and feed superficially rather than taking a blood meal.