Trombiculidae

Common Name

Chiggers, Harvest Mites, Red Bugs

Overview

Trombiculidae is a family of mites known for their parasitic larval stage, colloquially referred to as chiggers. These mites are primarily found in soil and leaf litter, with a widespread distribution across the globe, particularly in tropical and subtropical regions.

Taxonomy

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Arachnida
• Order: Trombidiformes
• Family: Trombiculidae

Key Characteristics

• Appearance: Larvae are typically red to orange and less than 0.3 mm in size.
• Larval Stage: Parasitic; attaches to vertebrate hosts.
• Life Stages: Egg, larva, nymph, adult.
• Feeding: Larvae feed on skin cells through a stylostome (a feeding structure); nymphs and adults are generally free-living and often predatory.

Life Cycle

1. Egg: Laid in the soil or leaf litter.
2. Larva: Parasitic stage that attaches to a host to feed.
3. Nymph: Free-living and undergoes several molts.
4. Adult: Free-living, often predatory.

Behavior and Ecology

Chiggers are commonly found in grassy fields, forests, and moist areas. Larvae attach to a host, where they feed for several days and then drop off to continue development in the soil. Nymphs and adults play roles in the decomposition of organic matter and soil aeration.

Notable Species

• Trombicula alfreddugesi: Widespread in North America, commonly affecting humans.
• Leptotrombidium deliense: Known vector of scrub typhus in Asia.
• Eutrombicula splendens: Found in Europe, parasitizing various vertebrate hosts.

Conservation

Trombiculidae are not currently a major focal group in conservation efforts. Their widespread habitat and resilience contribute to their stable populations.

Significance to Humans

Chigger bites can cause intense itching and dermatitis, commonly referred to as "chigger dermatitis." In some parts of the world, species like Leptotrombidium deliense are vectors for scrub typhus, a serious disease.

Fun Facts

• Tiny But Mighty: Chigger larvae are less than 0.3 mm in size, but their bites can cause significant irritation.
• Short-Term Guests: Chigger larvae generally feed on a host for only 3-5 days before dropping off.
• Sticky Situation: Chiggers use their stylostome to digest tissue, unlike many parasites that simply suck blood.
• Seasonal Guests: Chigger infestations are more common in late spring to early autumn when temperatures and humidity are higher.