53-540: Trombiculidae ( / t r ɒ m b ɪ ˈ k juː l ɪ d iː / ), 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 type of flea . Several species of Trombiculidae in their larva stage bite their animal host and by embedding their mouthparts into
106-425: A cephalothorax (with no separate head) or prosoma, and an opisthosoma or abdomen. Segmentation has almost entirely been lost and the prosoma and opisthosoma are fused, only the positioning of the limbs indicating the location of the segments. At the front of the body is the gnathosoma or capitulum. This is not a head and does not contain the eyes or the brain, but is a retractable feeding apparatus consisting of
159-563: A chrome-orange hue. There is a marked constriction in the front part of the body in the nymph and adult stages. The best known species of chigger in North America is the hard-biting Trombicula alfreddugesi of the Southeastern United States , humid Midwest and Mexico . In the UK, the most prevalent harvest mite is Neotrombicula autumnalis , which is distributed through Western Europe to Eastern Asia. Trombiculid mites go through
212-408: A prion disease of sheep. The mite Varroa destructor is a serious pest of honey bees , contributing to colony collapse disorder in commercial hives . This organism is an obligate external parasite, able to reproduce only in bee colonies. It directly weakens its host by sucking up the bee's fat, and can spread RNA viruses including deformed wing virus . Heavy infestation causes the death of
265-577: A colony, generally over the winter. Since 2006, more than 10 million beehives have been lost. Various mites prey on other invertebrates and can be used to control their populations. Phytoseiidae , especially members of Amblyseius , Metaseiulus , and Phytoseiulus , are used to control pests such as spider mites. Among the Laelapidae , Gaeolaelaps aculeifer and Stratiolaelaps scimitus are used to control fungus gnats , poultry red mites and various soil pests. Mites were first observed under
318-662: A doctor should be consulted. According to an Ohio State University Extension Fact Sheet: ... After returning from a chigger-infested area, launder the field clothes in soapy, hot water (50 °C (125 °F).) ... As soon as possible, take a good hot bath or shower and soap repeatedly. The chiggers may be dislodged, but you will still have the stylostomes, causing the severe itch. Scratching deep to remove stylostomes can cause secondary infections. 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 sooner
371-522: A few phylogenomic studies have found strong support for monophyly of Acari and a sister relationship between Acariformes and Parasitiformes, although this finding has been questioned, with other studies suggesting that this likely represents a long branch attraction artefact. Mites are tiny members of the class Arachnida ; most are in the size range 250 to 750 μm (0.01 to 0.03 in) but some are larger and some are no bigger than 100 μm (0.004 in) as adults. The body plan has two regions ,
424-477: A hole in the skin called a stylostome and chew up tiny parts of the inner skin, thus causing irritation and swelling. The 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. 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
477-404: A lifecycle of egg, larva, nymph , and adult. The larval mites feed on the skin cells of animals. The six-legged parasitic larvae feed on a large variety of creatures, including humans, rabbits, 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
530-439: A million or more species as yet undescribed. The tropical species Archegozetes longisetosus is one of the strongest animals in the world, relative to its mass (100 μg): It lifts up to 1,182 times its own weight, over five times more than would be expected of such a minute animal. A mite also holds a speed record: for its length, Paratarsotomus macropalpis is the fastest animal on Earth. The mites living in soil consist of
583-765: A network of sinuses and most mites lacks a heart, movement of fluid being driven by the contraction of body muscles. But ticks, and some of the larger species of mites, have a dorsal, longitudinal heart. Gas exchange is carried out across the body surface, but many species additionally have between one and four pairs of tracheae . The excretory system includes a nephridium and one or two pairs of Malpighian tubules . Several families of mites, such as Tetranychidae, Eriophyidae, Camerobiidae, Cunaxidae, Trombidiidae, Trombiculidae, Erythraeidae and Bdellidae have silk glands used to produce silk for various purposes. Additionally, water mites (Hydrachnidia) produce long thin threads that may be silk. The sexes are separate in mites; males have
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#1732868933644636-418: A pair of testes in the mid-region of the body, each connected to the gonopore by a vas deferens , and in some species there is a chitinous penis ; females have a single ovary connected to the gonopore by an oviduct , as well as a seminal receptacle for the storage of sperm . In most mites, sperm is transferred to the female indirectly; the male either deposits a spermatophore on a surface from which it
689-448: A range of taxa. Oribatida and Prostigmata are more numerous in soil than Mesostigmata, and have more soil-dwelling species. When soil is affected by an ecological disturbance such as agriculture, most mites (Astigmata, Mesostigmata and Prostigmata) recolonise it within a few months, whereas Oribatida take multiple years. Many mites are parasitic on plants and animals. One family of mites, Pyroglyphidae , or nest mites, live primarily in
742-542: A small scale, walking is used to access other suitable locations in the immediate vicinity. Some species mount to a high point and adopt a dispersal posture and get carried away by the wind, while others waft a thread of silk aloft to balloon to a new position. Parasitic mites use their hosts to disperse, and spread from host to host by direct contact. Another strategy is phoresy ; the mite, often equipped with suitable claspers or suckers, grips onto an insect or other animal, and gets transported to another place. A phoretic mite
795-505: A total of eight). Lastly, it re-enters inactivity during its transitional tritonymph phase before growing to adulthood. 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. They live in soil, and are often found when digging in yards or gardens or in compost bins. Recently (2018), methods based on autofluorescence microscopy were developed to enable identification of trombiculid mites to
848-576: A tube formed by hardened skin cells called a stylostome . They do not burrow into the skin or suck blood, as is commonly assumed. Itching from a chigger bite may not develop until 24–48 hours after the bite, so the victim may not associate the specific exposure with the bite itself. The red welt/bump on the skin is not where a chigger laid eggs, as is sometimes believed. The larvae remain attached to suitable hosts for three to five days before dropping off to begin their nymphal stage. They tend to attach where clothing has restrictions, such as belt lines, or behind
901-853: Is considered a dangerous pest in East Asia and the South Pacific because it often carries Orientia tsutsugamushi , the tiny bacterium that causes scrub typhus , which is known alternatively as the Japanese river disease, scrub disease, or tsutsugamushi . The mites are infected by the Rickettsia passed down from parent to offspring before eggs are laid in a process called transovarial transmission . Symptoms of scrub typhus in humans include fever, headache, muscle pain, cough, and gastrointestinal symptoms . Mite Mites are small arachnids (eight-legged arthropods ). Mites span two large orders of arachnids,
954-440: Is just a hitch-hiker and does not feed during the time it is carried by its temporary host. These travelling mites are mostly species that reproduce rapidly and are quick to colonise new habitats. Mites are tiny and apart from those that are of economic concern to humans, little studied. The majority are beneficial, living in the soil or aqueous environments and assisting in the decomposition of decaying organic material, as part of
1007-491: Is located on the ventral surface between the fourth pair of legs. Some species have one to five median or lateral eyes but many species are blind, and slit and pit sense organs are common. Both body and limbs bear setae (bristles) which may be simple, flattened, club-shaped or sensory. Mites are usually some shade of brown, but some species are red, orange, black or green, or some combination of these colours. Many mites have stigmata (openings used in respiration). In some mites,
1060-458: Is picked up by the female, or he uses his chelicerae or third pair of legs to insert it into the female's gonopore. In some of the Acariformes , insemination is direct using the male's penis. The spermatophora in all mites are aflagellate. The eggs are laid in the substrate , or wherever the mite happens to live. They take up to six weeks to hatch, according to species, with the next stage being
1113-415: Is the only parasitic stage of the mite's lifecycle. They are parasites on many animals. About 30 of the many species in this family, in their larval stage, attach to various animals and feed on skin. This often causes intensely itchy, red bumps in humans. Chiggers attach to the host, pierce the skin, inject enzymes into the bite wound that digest cellular contents, and then suck up the digested tissue through
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#17328689336441166-723: The Acariformes and the Parasitiformes , which were historically grouped together in the subclass Acari . However, most recent genetic analyses do not recover the two as each other's closest relative within Arachnida, rendering the group non- monophyletic . Most mites are tiny, less than 1 mm (0.04 in) in length, and have a simple, unsegmented body plan. The small size of most species makes them easily overlooked; some species live in water, many live in soil as decomposers , others live on plants, sometimes creating galls , while others are predators or parasites . This last type includes
1219-514: The Parasitiformes (sometimes known as Anactinotrichida). Recent genetic research has suggested that Acari is polyphyletic (of multiple origins). A study using molecular data from the mitochondria and nucleus recovered Acariformes as sister to the Solifugae (camel spiders) and Parasitiformes as sister to the Pseudoscorpionida , with other arachnid orders separating these two groupings on
1272-548: The Rhynie Chert , Scotland, which dates to the early Devonian , around 410 million years ago while the earliest fossils of Parasitiformes are known from amber specimens dating to the mid- Cretaceous , around 100 million years ago. Most fossil acarids are no older than the Tertiary (up to 65 mya ). Members of the superorders Opilioacariformes and Acariformes (sometimes known as Actinotrichida) are mites, as well as some of
1325-417: The carbon cycle . Two species live on humans, namely Demodex folliculorum and Demodex brevis ; both are frequently referred to as eyelash mites. The majority of mite species are harmless to humans and domestic animals , but a few species can colonize mammals directly, acting as vectors for disease transmission, and causing or contributing to allergenic diseases. Mites which colonize human skin are
1378-625: The chelicerae , the pedipalps and the oral cavity. It is covered above by an extension of the body carapace and is connected to the body by a flexible section of cuticle . Two-segmented chelicerae is the ancestral condition in Acariformes, but in more derived groups they are single-segmented. And three-segmented chelicerae is the ancestral condition in Parasitiformes, but has been reduced to just two segments in more derived groups. The pedipalps differ between taxa depending on diet; in some species
1431-511: The microscope by the English polymath Robert Hooke . In his 1665 book Micrographia , he stated that far from being spontaneously generated from dirt, they were "very prettily shap'd Insects". In 1898, Arthur Conan Doyle wrote a satirical poem, "A Parable", with the conceit of some cheese mites disputing the origin of the round cheddar cheese in which they all lived. The world's first science documentary featured cheese mites , seen under
1484-593: The Acari has been relatively little studied, but molecular information from ribosomal DNA is being extensively used to understand relationships between groups. The 18 S rRNA gene provides information on relationships among phyla and superphyla, while the ITS2 , and the 18S ribosomal RNA and 28S ribosomal RNA genes, provide clues at deeper levels. The mite fossil record is sparse, due to their small size and low preservation potential. The oldest fossils of acariform mites are from
1537-779: The British Isles where they are called harvest mites, the species Neotrombicula autumnalis are found during the summer and autumn (in French , harvest mites are called aoûtat because they are common in August). In the United States, they are found mostly in the Southeast, the South, and the Midwest . They are not present, or barely found, in far northern areas, high mountains, and deserts. In North America,
1590-401: The adult. This stage consists of three phases, the protonymph, deutonymph, and tritonymph. The protonymph and tritonymph morphologies are unusual in species of Trombiculidae. The protonymph phase combines larval and protonymph characteristics with deutonymph and tritonymph morphology. The protonymph is an inactive transitional stage. The active deutonymph develops an additional pair of legs (for
1643-546: The appendages resemble legs while in others they are modified into chelicerae-like structures. The oral cavity connects posteriorly to the mouth and pharynx . Most mites have four pairs of legs (two pairs in Eriophyoidea ), each with six segments, which may be modified for swimming or other purposes. The dorsal surface of the body is clad in hardened tergites and the ventral surface by hardened sclerites ; sometimes these form transverse ridges. The gonopore (genital opening)
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1696-642: The body of honey bees , and Acarapis woodi (family Tarsonemidae ) lives in their tracheae . Hundreds of species are associated with other bees, mostly poorly described. They attach to bees in a variety of ways. For example, Trigona corvina workers have been found with mites attached to the outer face of their hind tibiae. Some are thought to be parasites, while others are beneficial symbionts . Mites also parasitize some ant species, such as Eciton burchellii . Most larvae of Parasitengona are ectoparasites of arthropods, while later life stages in this group tend to shift to being predators. Plant pests include
1749-407: The cause of several types of itchy skin rashes, such as gamasoidosis , rodent mite dermatitis , grain itch , grocer's itch , and scabies ; Sarcoptes scabiei is a parasitic mite responsible for scabies, which is one of the three most common skin disorders in children. Demodex mites, which are common cause of mange in dogs and other domesticated animals, have also been implicated in
1802-437: The commercially destructive Varroa parasite of honey bees , as well as scabies mites of humans. Most species are harmless to humans, but a few are associated with allergies or may transmit diseases. The scientific discipline devoted to the study of mites is called acarology . The mites are not a defined taxon, but is used for two distinct groups of arachnids, the Acariformes and the Parasitiformes . The phylogeny of
1855-450: The cycle might be continuous all year long. Adult harvest mites winter in protected places such as slightly below the soil surface. Females become active in the spring, and once the ground temperature is regularly above 16 °C (60 °F), they lay eggs in vegetation, up to 15 eggs per day. The eggs are round and are dormant for about six days, after which the nonfeeding prelarvae emerge, with only three pairs of legs. After about six days,
1908-428: The disease rickettsialpox . House dust mites , found in warm and humid places such as beds, cause several forms of allergic diseases, including hay fever , asthma and eczema , and are known to aggravate atopic dermatitis . Among domestic animals , sheep are affected by the mite Psoroptes ovis which lives on the skin, causing hypersensitivity and inflammation. Hay mites are a suspected reservoir for scrapie ,
1961-444: The family was first described, it included two subfamilies, Hemitrombiculinae and Trombiculinae . Womersley added another, Leeuwenhoekiinae, which at the time contained only Leeuwenhoekia . 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. References to chiggers, however, go as far back as sixth-century China, and by 1733,
2014-443: The first recognition of trombiculid mites in North America was made. In 1758, Carl Linnaeus described a single species, Acarus batatas (now Trombicula batatas ). However, most information about chiggers came from problems that arose during and after World War II. Trombiculid mites are found throughout the world. In Europe and North America, they tend to be more prevalent in the hot and humid regions. In northern Europe, including
2067-417: The human skin disease rosacea , although the mechanism by which demodex contributes to the disease is unclear. Ticks are well known for carrying diseases, such as Lyme disease and Rocky Mountain spotted fever . Chiggers are known primarily for their itchy bite , but they can also spread disease in some limited circumstances, such as scrub typhus . The house-mouse mite is the only known vector of
2120-443: The knees when wearing jeans. During the wet season, chiggers are usually found in tall grass and other vegetation. During dry seasons, chiggers are mostly found underneath brush and shady areas. Standing still or lying in tall grass gives them more time to climb onto a person. Once the larva has gorged itself on skin and has fallen off its host, it develops to its nymph stage. The nymph is sexually immature, but more closely resembles
2173-612: The most diverse and successful of all invertebrate groups. They have exploited a wide array of habitats , and because of their small size go largely unnoticed. They are found in freshwater (e.g. the water mites or Hydrachnidia ) and saltwater (most Halacaridae ), in the soil, in forests, pastures, agricultural crops, ornamental plants, thermal springs and caves. They inhabit organic debris of all kinds and are extremely numerous in leaf litter. They feed on animals, plants and fungi and some are parasites of plants and animals. Some 48,200 species of mites have been described, but there may be
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2226-506: The nests of birds and other animals. These mites are largely parasitic and consume blood , skin and keratin . Dust mites , which feed mostly on dead skin and hair shed from humans instead of consuming them from the organism directly, evolved from these parasitic ancestors. Ticks are a prominent group of mites that are parasitic on vertebrates, mostly mammal and birds, feeding on blood with specialised mouthparts. Parasitic mites sometimes infest insects. Varroa destructor attaches to
2279-413: The phylogenetic tree, as shown below. Palpigradi False scorpions [REDACTED] Ixodida (ticks) [REDACTED] Parasitic mites, inc. Varroa [REDACTED] Trombidiformes (chiggers, velvet mites, etc) [REDACTED] Sarcoptiformes (dust & fur mites, etc) [REDACTED] Camel spiders [REDACTED] other Arachnids including spiders and scorpions However,
2332-413: The postlarval stages, they are not parasitic and feed on plant material. The females lay three to eight eggs in a clutch, usually on a leaf or among the roots of a plant, and die by autumn. 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. Then, when
2385-413: The prelarvae grow into their larval stage. 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. The larval stage
2438-441: The saliva cause "the intensely itchy welts". The itching can be alleviated through use of over-the-counter topical corticosteroids and antihistamines. 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. Hot showers or baths also help reduce itching. In cases of severe dermatitis or secondary infection associated with chigger bites,
2491-564: The six-legged larvae. After three moults, the larvae become nymphs, with eight legs, and after a further three moults, they become adults. Longevity varies between species, but the lifespan of mites is short compared to many other arachnids. Mites occupy a wide range of ecological niches . For example, Oribatida mites are important decomposers in many habitats. They eat a wide variety of material including living and dead plant and fungal material, lichens and carrion; some are predatory , though no oribatid mites are parasitic . Mites are among
2544-693: The skin cause "intense irritation", or "a wheal , usually with severe itching and dermatitis ". Humans are possible hosts. Trombiculidae live in forests and grasslands and are also found in the vegetation of low, damp areas such as woodlands, berry bushes, orchards, along lakes and streams, and even in drier places where vegetation is low, such as lawns, golf courses, and parks. They are most numerous in early summer when grass, weeds, and other vegetation are heaviest. In their larval stage, they attach to various animals, including humans, and feed on skin, often causing itching. These relatives of ticks are nearly microscopic, measuring 400 μm (1/60 of an inch) and have
2597-477: The so-called spider mites (family Tetranychidae ), thread-footed mites (family Tarsonemidae ), and the gall mites (family Eriophyidae ). Among the species that attack animals are members of the sarcoptic mange mites (family Sarcoptidae ), which burrow under the skin. Demodex mites (family Demodecidae ) are parasites that live in or near the hair follicles of mammals , including humans. Being unable to fly, mites need some other means of dispersal. On
2650-473: The species Trombicula alfreddugesi , and the species Trombicula (eutrombicula) hirsti , which are found in Australia and are commonly called the scrub-itch mite. The length of the mite's cycle depends on species and environment, but normally lasts two to 12 months. The number of cycles in a year depends on the region. For example, in a temperate region, only three per year may occur, but in tropical regions,
2703-531: The species level on the basis of morphological traits without any special preparation. Trombiculosis, also called trombiculiasis and trombiculidiasis, is the term coined for the rash or infestation caused by trombiculid mite larvae. 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. The chiggers' digestive enzymes in
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#17328689336442756-505: The stigmata are associated with peritremes: paired, tubular, elaborated extensions of the tracheal system. The higher taxa of mites are defined by these structures: Mite digestive systems have salivary glands that open into the preoral space rather than the foregut. Most species carry two to six pairs of salivary glands that empty at various points into the subcheliceral space. A few mite species lack an anus: they do not defecate during their short lives. The circulatory system consists of
2809-547: The treatment, the better the results.) Home remedies to "suffocate" the mite, such as applying clear nail polish, rubbing alcohol, or bleach, may have little benefit since the mites do not burrow into the skin. However, since the mite may still be attached for up to three days, these treatments could possibly kill the mite, reducing further damage. Although the harvest mite chigger usually does not carry diseases in North American temperate climates , Leptotrombidium deliense
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