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''Trombicula'', known as chiggers, red bugs, scrub-itch mites, or berry bugs, are small
arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaro ...
s (eight-legged
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, o ...
s) in the
Trombiculidae Trombiculidae (); commonly referred to in North America as chiggers and in Britain as harvest mites, but also known as berry bugs, bush-mites, red bugs or scrub-itch mites, are a family of mites. Chiggers are often confused with jiggers – a t ...
family. In their larval stage, they attach to various animals, including humans, and feed on skin, often causing itching and
trombiculosis Trombiculosis is a rash caused by trombiculid mites, especially those of the genus '' Trombicula'' (chiggers). The rash is also often known as chigger bites. Prevention Chiggers are commonly found on the tip of blades of grasses to catch a h ...
. These relatives of
tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s 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 ''Trombicula alfreddugesi'', also called ''Eutrombicula alfreddugesi'', is a species in the genus '' Trombicula''. ('' Eutrombicula'' is a subgenus of mites in ''Trombicula'' of the family Trombiculidae.) It is the common chigger species of the ...
''. The larval mites feed on the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...
cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
s, but not blood, of
animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...
s. The six-legged parasitic
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. Th ...
feeds on a large variety of creatures, including
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, an ...
s,
rabbit Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit specie ...
s, wallabies,
toad Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. A distinction between frogs and toads is not made in scientif ...
s,
box turtle Box turtle is the common name for several species of turtle. It may refer to those of the genus '' Cuora'' or '' Pyxidea'', which are the Asian box turtles, or more commonly to species of the genus '' Terrapene'', the North American box turtles. ...
s,
quail Quail is a collective name for several genera of mid-sized birds generally placed in the order Galliformes. The collective noun for a group of quail is a flock, covey, or bevy. Old World quail are placed in the family Phasianidae, and New W ...
, and even some
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of ...
s. After crawling onto their
host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ...
s, 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 The stylostome is a funnel- or channel-like structure formed in response to trombiculid mites. The formation is not caused by the mouthparts of the mites, because these mites do not have needle-like mouthparts as other hematophagous animals have ...
, 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 (
papule A papule is a small, well-defined bump in the skin. It may have a rounded, pointed or flat top, and may have a dip. It can appear with a stalk, be thread-like or look warty. It can be soft or firm and its surface may be rough or smooth. Some h ...
s) or
hives Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and does not leave any long-lasti ...
and
skin rash A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cr ...
or lesions on a sun-exposed area. For humans, itching usually occurs after the larvae detach from the skin. After feeding on their hosts, the larvae drop to the ground and become nymphs, then mature into adults, which have eight legs and are harmless to humans. In the postlarval stage, they are not parasitic and feed on plant materials. The females lay three to eight eggs in a clutch, usually on a leaf or under the roots of a plant, and die by autumn.


Distribution

Species in the genus ''Trombicula'' are found throughout the world. In Europe and North America, they tend to dwell in hot and humid climates. In more temperate regions, they are found only in summer. (In France, for example, they are called ''aoûtat'', after ''août'', August; ''vendangeon'', after ''vendange'', harvest; or ''rouget'', after ''rouge'', red.) In the United States, they are found mostly in the southeast, the south, and the Midwest. They are rarely found in far northern areas, high mountains or deserts. They live in low, damp areas within forests and grasslands, as well as in drier environments places where vegetation is low-growing but profuse, such as lawns, golf courses and parks. They are most numerous in early summer when grass, weeds and other vegetation are most prevalent. Harvest mites can also find their way into homes via human hosts who have passed through such areas.


Taxonomy

Species include:IRMNG (2018). ''Trombicula'' Berlese, 1905. Accessed at: http://www.irmng.org/aphia.php?p=taxdetails&id=1102956 on 2019-01-16


See also

*
Chigger bite Trombiculosis is a rash caused by trombiculid mites, especially those of the genus '' Trombicula'' (chiggers). The rash is also often known as chigger bites. Prevention Chiggers are commonly found on the tip of blades of grasses to catch a ...
* Human parasite * List of human parasites


References

* '' The
World Book Encyclopedia The ''World Book Encyclopedia'' is an American encyclopedia. The encyclopedia is designed to cover major areas of knowledge uniformly, but it shows particular strength in scientific, technical, historical and medical subjects. ''World Book'' wa ...
'', 2000 ed. * ''
Encyclopædia Britannica The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various time ...
'', 2005 ed. . * *


External links


"Chiggers!" at Missouri Department of Conservation

Iowa State University Department of Entomology Insect Information Note




* ttp://www.the-piedpiper.co.uk/th5i.htm#harvestmite ''Trombicula autmunalis'' {{Taxonbar, from=Q14830884 Trombiculidae