Trombicula, known as chiggers, red bugs, scrub-itch mites, or berry bugs, are small arachnids (eight-legged arthropods) in the Trombiculidae family. In their larval stage, they attach to various animals and humans, then feed on skin, often causing itching and trombiculosis. These relatives of ticks are nearly microscopic, measuring 0.4 mm (0.01 in), and have a chrome-orange hue. A common species of harvest mite in North America is Trombicula alfreddugesi.
The larval mites feed on the skin cells, but not blood, of animals. The six-legged parasitic larva feeds on a large variety of creatures, including humans, rabbits, wallabies, toads, box turtles, quail, and even some insects. After crawling onto their hosts, they inject digestive enzymes into the skin that break down skin cells. They do not actually "bite", but instead form a hole in the skin called a stylostome, and chew up tiny parts of the inner skin, thus causing severe irritation and swelling. The severe itching is accompanied by red pimple-like bumps (papules) or hives and skin rash or lesions on a sun-exposed area. For humans, itching usually occurs after the larvae detach from the skin.
