Warble fly

Warble fly is a name given to the genus Hypoderma, large flies which are parasitic on cattle and deer. Other names include "heel flies", "bomb flies" and "gadflies", while their larvae are often called "cattle grubs" or "wolves." Common species of warble fly include Hypoderma bovis (the ox warble fly) and Hypoderma lineatum (cattle) and Hypoderma tarandi (the reindeer warble fly). Larvae of Hypoderma species also have been reported in horses, sheep, goats and humans.[1] They have also been found on smaller mammals such as dogs, cats, squirrels, voles and rabbits.

Adult warble flies are large, hairy and bumblebee-like and brown, orange or yellow in color. The adults have vestigial mouthparts, so they cannot feed during their short lifespans, which can be as little as five days.[2]

They are found on all continents of the Northern Hemisphere, mainly between 25° and 60° latitude.

Warble flies
The ox warble fly (Hypoderma bovis). Pen and ink drawing by Wellcome V0022585
Ox warble fly (Hypoderma bovis)
Ox Warble-fly
Life cycle
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Oestridae
Subfamily: Hypodermatinae
Genus: Hypoderma
Latreille, 1818


The fly lays eggs on the forelegs of large animals. The eggs hatch within a week and penetrate the skin, where they migrate throughout the connective tissues (H. bovis) or to the esophagus (H. lineatum). After a few months, the larvae travel back to the skin surface and cause swellings called "warbles". They remain under the skin, and when destroyed by pressure, the larvae can cause large purulent swellings, or anaphylaxis. Upon emergence, the fly leaves holes in the skin. Large numbers of such punctures can render cattle hides valueless.

The migrating larvae can cause damage to meat, as the tunnels they make in the muscle fill with a substance known as "butcher's jelly".[2] Infestations also hinder weight gain and growth in the animals. Milk yields may also decline. Most infections in adult cows are minor, due to immunity developed over time.


In humans, the disease intracerebral myiasis is a rare infestation of the brain by the larva of H. bovis. It penetrates the brain by an unknown mode and causes symptoms such as convulsions and intracerebral hematoma. The first case of human warble fly infection in Britain (to a four-year-old boy on a farm near South Brent, Devon) was reported in the British Medical Journal in June 1924 by Dr Frederick William Style[3] Other cases appear in medical literature.[4] Myiasis of the human eye can be caused by H. tarandi, a parasite of reindeer. It is known to cause uveitis, glaucoma and retinal detachment.[5] H. lineatum and H. sinense may also infest humans.[5]

Treatment and prevention

Warble flies have been eradicated in many countries, beginning with Denmark and Western Germany, in the 1960s. It was eradicated in the United Kingdom in 1990.[6][7] It is a notifiable disease. It may have been eradicated from Belgium.

From the 1980s, the preventive treatment is easier, by subcutaneous use of ivermectin, but the warble fly remains present in North Africa.

Hypoderma bovis larvae young
Warble fly larvae

See also


  1. ^ The Merck Veterinary Manual.
  2. ^ a b Piper, R. (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals. Greenwood Press.
  3. ^ Style, F. W (1924). "The Larva of the Warble-Fly as a Human Parasite". British Medical Journal. 1 (3312): 1086–1087. doi:10.1136/bmj.1.3312.1086. PMC 2304562. PMID 20771637.
  4. ^ Kalelioğlu, M.; et al. (December 1989). "Intracerebral myiasis from Hypoderma bovis larva in a child. Case report". J. Neurosurg. 71 (6): 929–931. doi:10.3171/jns.1989.71.6.0929. PMID 2585086.
  5. ^ a b Lagacé-Wiens, P. R., et al. (2008). Human ophthalmomyiasis interna caused by Hypoderma tarandi, Northern Canada. Emerging Infectious Diseases 14(1), 64.
  6. ^ "Defra website (archive): Warble fly".
  7. ^ "Explanatory Note to the Animal Health (Miscellaneous Revocations)(England and Wales) Order 2015".

External links

Agriculture in the United Kingdom

Agriculture in the United Kingdom uses 69% of the country's land area, employs 1.5% of its workforce (476,000 people) and contributes 0.62% of its gross value added (£9.9 billion). The UK produces less than 60% of the food it eats. Although agricultural activity occurs in most rural locations, it is concentrated in East Anglia (for crops) and the South West (livestock). Of the 212,000 farm holdings, there is a wide variation in size from under 20 to over several thousand hectares.Despite skilled farmers, high technology, fertile soil and subsidies, farm earnings are relatively low, mainly due to low prices at the farm gate. Low earnings, high land prices and a shortage of let farmland discourage young people from joining the industry. The average age of the British farm holder is now 59.Recently there have been moves towards organic farming in an attempt to sustain profits, and many farmers supplement their income by diversifying activities away from pure agriculture. Biofuels present new opportunities for farmers against a background of rising fears about fossil fuel prices, energy security, and climate change. There is increasing awareness that farmers have an important role to play as custodians of the British countryside and wildlife.


Apitherapy is a branch of alternative medicine that uses honey bee products, including honey, pollen, propolis, royal jelly and bee venom. Proponents of apitherapy make claims for its health benefits which are unsupported by evidence-based medicine.


Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies technically known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. Dermatobia hominis is the only species of botfly known to parasitize humans routinely, though other species of flies cause myiasis in humans.

Cephenemyia trompe

Cephenemyia trompe, also known as the reindeer nose botfly, is a species of botfly first described by Adolph Modéer in 1786. It belongs to the deer botflygenus Cephenemyia. This fly is parasitic on reindeer. It is one of two Cephenemyia species found only in Scandinavia.The larvae of Cephenemyia trompe infect the nose area of reindeer. The adult is active during the Arctic summer, being able to fly very fast and having developed olfactory abilities to find reindeer from long distances. Its activity, however, is inhibited by strong winds, low temperatures and rain or snow. This species has a very short pupariation time compared to other reindeer botfly species.

Dermatobia hominis

The human botfly, Dermatobia hominis (Greek δέρμα, skin + βίος, life, and Latin hominis, of a human), is one of several species of flies, the larvae of which parasitise humans (in addition to a wide range of other animals, including other primates). It is also known as the torsalo or American warble fly, though the warble fly is in the genus Hypoderma and not Dermatobia, and is a parasite on cattle and deer instead of humans.

Dermatobia fly eggs have been shown to be vectored by over 40 species of mosquitoes and muscoid flies, as well as one species of tick; the female captures the mosquito and attaches its eggs to its body, then releases it. Either the eggs hatch while the mosquito is feeding and the larvae use the mosquito bite area as the entry point, or the eggs simply drop off the muscoid fly when it lands on the skin. The larvae develop inside the subcutaneous layers, and after about 8 weeks, they drop out to pupate for at least a week, typically in the soil. The adults are large flies resembling bumblebees. They are easily recognized because they lack mouthparts (as is true of other oestrid flies).

This species is native to the Americas from southeastern Mexico (beginning in central Veracruz) to northern Argentina, Chile, and Uruguay, though it is not abundant enough (nor harmful enough) to ever attain true pest status. Some cases have also been reported in Europe. Since the fly larvae can survive the entire 8-week development only if the wound does not become infected, patients rarely experience infections unless they kill the larva without removing it completely.

Flea circus

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Hypoderma tarandi

Hypoderma tarandi, also known as the reindeer warble fly and reindeer botfly, is a species of warble fly that is parasitic on reindeer.The larvae of this fly are a skin-penetrating ectoparasite that usually infest populations of reindeer and caribou in Arctic areas, causing harm to the hides, meat and milk in domesticated herds. They also may cause ophthalmomyiasis in humans, leading to uveitis, glaucoma and retinal detachment. H. lineatum and H. sinense may also infest humans.

Hypodermin C

Hypodermin C (EC, Hypoderma collagenase) is an enzyme. This enzyme catalyses the following chemical reaction

Hydrolysis of proteins including native collagen at -Ala bond leaving an N-terminal (75%) and a C-terminal (25%) fragmentThis enzyme is isolated from the larva of a warble fly, Hypoderma lineatum.

List of Statutory Instruments of the United Kingdom, 1987

For the main article see Statutory Instruments.This is a complete list of all 1468 Statutory Instruments published in the United Kingdom in the year 1987.

List of Statutory Instruments of the United Kingdom, 1989

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List of Statutory Instruments of the United Kingdom, 1995

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List of animals displaying homosexual behavior

For these animals, there is documented evidence of homosexual behavior of one or more of the following kinds: sex, courtship, affection, pair bonding, or parenting, as noted in researcher and author Bruce Bagemihl's 1999 book Biological Exuberance: Animal Homosexuality and Natural Diversity.

Bagemihl writes that the presence of same-sex sexual behavior was not "officially" observed on a large scale until the 1990s due to possible observer bias caused by social attitudes towards nonheterosexual people, making the homosexual theme taboo. Bagemihl devotes three chapters; Two Hundred Years at Looking at Homosexual Wildlife, Explaining (Away) Animal Homosexuality and Not For Breeding Only in his 1999 book Biological Exuberance to the "documentation of systematic prejudices" where he notes "the present ignorance of biology lies precisely in its single-minded attempt to find reproductive (or other) 'explanations' for homosexuality, transgender, and non-procreative and alternative heterosexualities." Petter Bøckman, academic adviser for the Against Nature? exhibit stated "[M]any researchers have described homosexuality as something altogether different from sex. They must realize that animals can have sex with who they will, when they will and without consideration to a researcher's ethical principles." Homosexual behavior is found amongst social birds and mammals, particularly the sea mammals and the primates.Sexual behavior takes many different forms, even within the same species and the motivations for and implications of their behaviors have yet to be fully understood. Bagemihl's research shows that homosexual behavior, not necessarily sex, has been documented in about five hundred species as of 1999, ranging from primates to gut worms. Homosexuality in animals is seen as controversial by social conservatives because it asserts the naturalness of homosexuality in humans, while others counter that it has no implications and is nonsensical to equate natural animal behaviors to morality. Sexual preference and motivation is always inferred from behavior. Thus homosexual behavior has been given a number of terms over the years. The correct usage of the term homosexual is that an animal exhibits homosexual behavior, however this article conforms to the usage by modern research, applying the term homosexuality to all sexual behavior (copulation, genital stimulation, mating games and sexual display behavior) between animals of the same sex.

Mark Purdey

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Parasitic flies of domestic animals

Many species of flies of the two-winged type, Order Diptera, such as mosquitoes, horse-flies, blow-flies and warble-flies, cause direct parasitic disease to domestic animals, and transmit organisms that cause diseases. These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high. These problems occur wherever domestic animals are reared. This article provides an overview of parasitic flies from a veterinary perspective, with emphasis on the disease-causing relationships between these flies and their host animals. The article is organized following the taxonomic hierarchy of these flies in the phylum Arthropoda, order Insecta. Families and genera of dipteran flies are emphasized rather than many individual species. Disease caused by the feeding activity of the flies is described here under parasitic disease. Disease caused by small pathogenic organisms that pass from the flies to domestic animals is described here under transmitted organisms; prominent examples are provided from the many species.

Puerto Rican sharp-shinned hawk

The Puerto Rican sharp-shinned hawk, (Accipiter striatus venator), falcón de sierra or gavilán pecho rufo in Spanish, is an endemic subspecies of the North American sharp-shinned hawk, occurring only in Puerto Rico. Discovered in 1912 and described as a distinct sub-species, it has been placed on the United States Fish and Wildlife Service list of endangered species because of its rapidly dwindling population in Puerto Rico. It can be found in the Toro Negro State Forest.


The reindeer (Rangifer tarandus), also known as the caribou in North America, is a species of deer with circumpolar distribution, native to Arctic, sub-Arctic, tundra, boreal, and mountainous regions of northern Europe, Siberia, and North America. This includes both sedentary and migratory populations. Rangifer herd size varies greatly in different geographic regions. The Taimyr herd of migrating Siberian tundra reindeer (R. t. sibiricus) in Russia is the largest wild reindeer herd in the world, varying between 400,000 and 1,000,000. What was once the second largest herd is the migratory boreal woodland caribou (R. t. caribou) George River herd in Canada, with former variations between 28,000 and 385,000. As of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the Canadian Broadcasting Corporation. The New York Times reported in April 2018 of the disappearance of the only herd of southern mountain caribou in the lower 48 states, with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals.Rangifer varies in size and colour from the smallest, the Svalbard reindeer, to the largest, the boreal woodland caribou. The North American range of caribou extends from Alaska through Yukon, the Northwest Territories and Nunavut into the boreal forest and south through the Canadian Rockies and the Columbia and Selkirk Mountains. The barren-ground caribou, Porcupine caribou, and Peary caribou live in the tundra, while the shy boreal woodland caribou prefer the boreal forest. The Porcupine caribou and the barren-ground caribou form large herds and undertake lengthy seasonal migrations from birthing grounds to summer and winter feeding grounds in the tundra and taiga. The migrations of Porcupine caribou herds are among the longest of any mammal. Barren-ground caribou are also found in Kitaa in Greenland, but the larger herds are in Alaska, the Northwest Territories, and Nunavut.Some subspecies are rare and at least one has already become extinct: the Queen Charlotte Islands caribou of Canada. Historically, the range of the sedentary boreal woodland caribou covered more than half of Canada and into the northern States in the U.S. Woodland caribou have disappeared from most of their original southern range and were designated as threatened in 2002 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Environment Canada reported in 2011 that there were approximately 34,000 boreal woodland caribou in 51 ranges remaining in Canada.(Environment Canada, 2011b). Siberian tundra reindeer herds are in decline, and Rangifer tarandus is considered to be vulnerable by the IUCN.

Arctic peoples have depended on caribou for food, clothing, and shelter, such as the Caribou Inuit, the inland-dwelling Inuit of the Kivalliq Region in northern Canada, the Caribou Clan in Yukon, the Inupiat, the Inuvialuit, the Hän, the Northern Tutchone, and the Gwich'in (who followed the Porcupine caribou for millennia). Hunting wild reindeer and herding of semi-domesticated reindeer are important to several Arctic and sub-Arctic peoples such as the Duhalar for meat, hides, antlers, milk, and transportation. The Sami people (Laplanders) have also depended on reindeer herding and fishing for centuries. In Lapland, reindeer pull pulks.Male and female reindeer can grow antlers annually, although the proportion of females that grow antlers varies greatly between population and season. Antlers are typically larger on males. In traditional festive legend, Santa Claus's reindeer pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve.

Sussex dialect

The Sussex dialect is a dialect that was once widely spoken by those living in the historic county of Sussex in southern England. Much of the distinctive vocabulary of the Sussex dialect has now died out, although a few words remain in common usage and some individuals still speak with the traditional Sussex accent.

The Sussex dialect is a subset of the Southern English dialect group. Historically, there were three main variants to the dialect: west Sussex (west of Shoreham and the river Adur), mid Sussex (between the Adur and Hastings) and east Sussex (from Hastings eastwards). There were also differences between downland and Wealden communities. In particular, the people of the Weald were thought to have the most impenetrable accents. The Sussex dialect shows remarkable continuity: the three main dialect areas reflect the historic county's history. The west and mid dialect areas reflect the ancient division of Sussex between East and West, which until the creation of the rape of Bramber in the 11th century lay along the river Adur. The eastern dialect area reflects the unique history of the Hastings area, which was home to the kingdom of the Haestingas until the 8th century.

Sussex dialect words have their sources in many historic languages including Anglo-Saxon, Old Dutch, a dash of 14th-century Middle French, and a little Scandinavian. Many words are thought to have derived from Sussex's fishermen and their links with fishermen from the coasts of France and the Netherlands.


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