The best known species of chigger in North America[11] is the hard-biting Trombicula alfreddugesi of the Southeastern United States, humid Midwest[12] and Mexico.

In the UK, the most prevalent harvest mite is Neotrombicula autumnalis, which is distributed through Western Europe to Eastern Asia.

The six-legged parasitic larvae feed on a large variety of creatures, including humans, rabbits, toads, box turtles, quail, and even some insects.

The itching is accompanied by red, pimple-like bumps (papules) or hives and skin rash or lesions on a sun-exposed area.

[15] Trombiculidae, from Greek τρομειν ("to tremble") and Latin culex, genitive culicis ("gnat" or "midge"), was first described as an independent family by Henry Ellsworth Ewing in 1944.

Later, he erected the family Leeuwenhoekiidae for the genus and subfamily, having six genera; they have a pair of submedian setae present on the dorsal plate.

[17] References to chiggers, however, go as far back as sixth-century China, and by 1733, the first recognition of trombiculid mites in North America was made[citation needed].

[14] The larvae, commonly called chiggers, are about 170–210 μm (0.007–0.008 in) in diameter, normally light red in color, and covered in hairs; they move quickly relative to size.

The larvae congregate in groups on small clods of soil, in matted vegetation, and even on low bushes and plants, where they have more access to prospective hosts.

[14] As deutonymphs and adults, trombiculid mites are independent predators that feed on small arthropods and their eggs, and are also found to eat plant material.

Recently (2018), methods based on autofluorescence microscopy were developed to enable identification of trombiculid mites to the species level on the basis of morphological traits without any special preparation.

[29] Trombiculosis, also called trombiculiasis and trombiculidiasis, is the term coined for the rash or infestation caused by trombiculid mite larvae.

[30][31] Because chigger wounds are a complex combination of enzymatic and the resulting mechanical damage, plus allergy and immune responses, plus possible secondary bacterial infection subject to local influences, no one remedy works equally well for most people.

According to Mayo Clinic, the chiggers "fall off after a few days, leaving behind red, itchy welts", which normally heal on their own within one to two weeks.

According to an Ohio State University Extension Fact Sheet:[35] ... After returning from a chigger-infested area, launder the field clothes in soapy, hot water (50 °C (125 °F).)

For temporary relief of itching, apply ointments of benzocaine, hydrocortisone, calamine lotion, New Skin, After Bite, or others recommended by your pharmacist or medical doctor. ...

The mites are infected by the Rickettsia passed down from parent to offspring before eggs are laid in a process called transovarial transmission.