Harvest mite
| Harvest Mite Conservation status: Secure | ||||||||||||||
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| Missing image Chigger_larva.jpg Harvest mite larva | ||||||||||||||
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| Trombicula alfreddugesi |
Harvest mites (Trombicula alfreddugesi; also known as the Red bug, Trombiculid mite or Scrub-itch mite) are mites in the family Trombiculidae that live in berry patches, tall grass and weeds, woodland edges, pine straw, leaves, and treebark. These relatives of spiders are nearly microscopic measuring 0.4mm (1/100 of an inch) and have a chrome-orange hue. The chigger's six-legged parasitic larva will crawl onto humans, rabbits, toads, box turtles, quail, and even some insects, and bite the host. They inject digestive enzymes into the skin that break down skin cells.
Harvest mite larvae are small, red nymphs which have not yet become an adult mite. They are usually microscopic and can not be seen with the naked eye. The larvae often live in forests and grasslands, but some may also live in water.
The larvae mites feed on the skin cells, but not blood, of both humans and animals. The six-legged parasitic larva will crawl onto humans, rabbits, toads, box turtles, quail, and even some insects. After crawling onto their host, 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 and chew up tiny parts of the inner skin, thus causing severe irritation and swelling. The severe itching is accompanied with red pimple-like bumps (papules) or hives and skin rash or lesion on a sun-exposed area. For humans, itching usually occurs after the larvae detach from the skin.
Chigger_adult.jpg
After feeding on their hosts, the larvae drop to the ground and become nymphs. After they drop off their hosts, the larvae mature into adults, which have 8 legs and do not harm humans. During this stage, they are not parasitic and feed on plant materials. The females lay 3-8 eggs in a litter, usually on a leaf or under the roots of a plant, and die by autumn.
Contrary to popular belief, the larvae do not burrow deep into the skin and live there, and neither do coverings such as fingernail polish kill the chigger per se.
Though the harvest mite chigger usually does not carry diseases in North American temperate climates, the mites are considered a dangerous pest in East Asia and the South Pacific because they often carry scrub typhus, which is known alternatively as the Japanese river disease, scrub disease, or tsutsugamushi. The mites usually are infected by the disease by their infected rodent hosts. The disease is transmitted to the next generation of offspring by breeding mites. Symptoms of scrub typhus in humans include fever, headache, muscle pain, cough, and gastrointestinal symptoms.
If you have been "bitten" by chiggers, do not scratch the affected regions. Scratching could scrape off chigger larvae, but it may also cause more irritation by breaking the skin and leaving it vulnerable to infection. The most effective way of removing chiggers is by taking a hot shower and washing the affected areas with mildly hot water and soap. Do not rub and scratch the skin aggressively, but instead gently but firmly rub the irritated skin. A covering to reduce air exposure over the itchy area, such as calamine lotion, petroleum jelly, or baby oil, may help relieve the pain, but they do not cure the bites.
To avoid being attacked by chiggers, always wear tight weave, protective clothing and long pants. Spray insect repellent on your skin for further protection. Staying on trails, roads, or paths can help prevent you from meeting chiggers, ticks, spiders, snakes, and other nuisances and dangers.
Insect repellents generally contain one of the following active ingredients are recommended: DEET, Catnip oil extract - Nepetalactone, Citronella or eucalyptus oil extract.
See also
References
- The World Book Encyclopedia, 2000 ed.
- Encyclopaedia Britannica, 2005 ed. Accessed with paid subscription.
- Tideland Treasure: The Naturalist's Guide to the Beaches and Salt Marshes of Hilton Head Island and the Southeastern Coast, Revised Edition, by Todd Ballantine.
External links
- Description of chiggers
- Chiggers at Pestproducts.com
- Ohio State University Extension Fact Sheet, Entomology, Chiggers, HYG-2100-98
- Iowa State University Department of Entomology Insect Information Note
- NIH Medline Plus