Haematobia irritans
Encyclopedia
Haematobia irritans, the horn fly, is a small fly
(about half the size of a common housefly
) of the genus
Haematobia
which is the Europe
an genus of bloodsucking flies. Haematobia irritans is a native of Europe but has been introduced to North America
and is considered a potentially dangerous livestock pest.
, gray in color, approximately in (4.0 mm) in length. Both the male and female have slender, black, piercing mouthparts
which project forward from the bottom of the head. They often aggregate densely on cattle
, each fly oriented with its head in the same direction as hair tips of that site on the host. Horn flies typically have eyes that are dark reddish-brown.
The larva
e remain in fresh pats of the animal's dung and feed on both the resident bacterium and the compositions of the decomposition products of the resident bacterium.
The adult will finds a suitable host and remains on it and others in the same herd for life, with the female only leaving to lay her eggs. Horn flies will also move around to different areas on the same animal to regulate their temperature and minimize their exposure to the wind. Both the male and the female subsist completely on blood
, using their sharp mouthparts to pierce the animal's hide to suck it out.
Males typically feed around 20 times and females around 40 times daily, and when not feeding they tend to rest around the horn region of the host.
The first stage is the egg, which is laid in fresh feces, and hatches quickly. The resulting larval (maggot
) stage, which consists of three larval instars (wingless), develops quickly and can last as little as four days. This is followed by the still immature pupa stage (also wingless) which lasts around six to eight days and finally the mature, winged adult stage.
Generational time may be as little as ten days under ideal conditions, but under less favorable circumstances can average between 14 to 18 days.
. Haematobia irritans is not native to the U.S. and originally came from Europe. It can live in any similarly climatized area, as evidenced by its most recent spread to Argentina
and Uruguay
. In the U.S., the active time of the horn fly is between April and October and, in a warm fall, even as late as mid-November. The flies are often most abundant from June through mid-July with a second population peak in mid-to-late August.
Due to the level of damage an infestation can result in, much has been done over the years in the effort to manage, reduce, and eliminate the horn fly. Traditional methods were through the use of pour-ons, backrubbers and face powder bags, with products such as Co-Ral which is available as dust for face/horn flies. Self-applicator methods such as dust bags and backrubbers are used mainly for range or pasture herds, and are placed so that the animal cannot avoid coming into contact with it, such as at a gate through which animals pass. More recently, control of the horn fly by using ear tags on cattle has been extremely successful. The ear tags are made of a PVC
matrix impregnated with pyrethroid
, and can be effective for between 16 to 24 weeks. Originally, the ear tags were developed and used against such pests as tick
s and by 1983 50% of cattle had ear tags. Long periods of such dosing resulted in the elimination of 95-99% of susceptible flies, but this strong selection pressure ended up resulting in the development of resistant strains of the flies. To combat this, the use of organophosphate
s and piperonyl butoxide
as a synergist
are now recommended to be alternated with pyrethroid to help slow resistance. In addition, methoprene
in the form of sustained release bolus (a rounded mass of food or pharmaceutical preparation ready to swallow) inhibits the emergence of an adult insect from a pupal case or an insect larvaa from an egg for up to 7 months.
New research (2011) has shown essential oil vapors from 16 species of Eucalyptus
to have toxicity against Haematobia irritans.
. This is apparently a spontaneous mutation
, as tests including crosses were performed that determined the white-eye mutation was not sex-linked
and the white-eyed flies actually have decreased amounts of eye pigment present within the head. This appears to be an inherited simple Mendelian
autosomal recessive
with complete penetrance
. A colony of white-eyed horn flies was established from this single individual and has been maintained in the laboratory as visible genetic markers such as an eye color mutation in an economically important species like the horn fly may be useful for behavior and population dynamic studies, as well as release and recapture studies. No other differences from the wild-type flies were detected in the external characteristics of the mutant phenotype
or in egg viability. However, white-eyed flies had significantly lower amounts of the pigment dihydroxyxanthommatin in their heads suggesting either the lack of xanthommatin production, or a failure of transport and storage within the head of the mutant phenotype.
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
(about half the size of a common housefly
Housefly
The housefly , Musca domestica, is a fly of the suborder Cyclorrhapha...
) of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Haematobia
Haematobia
Haematobia is a genus of biting true flies of the family Muscidae. -Species:*H. exigua de Meijere, 1906*H. irritans *H. spinigera Malloch, 1932...
which is the Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an genus of bloodsucking flies. Haematobia irritans is a native of Europe but has been introduced to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and is considered a potentially dangerous livestock pest.
Appearance
H. irritans is the smallest of the biting muscidsMuscidae
Muscidae are a family of flies found in the superfamily Muscoidea. The apical segment of the antennae of Muscidae are plumose, and the basal portion is smooth....
, gray in color, approximately in (4.0 mm) in length. Both the male and female have slender, black, piercing mouthparts
Insect mouthparts
Insects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...
which project forward from the bottom of the head. They often aggregate densely on cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
, each fly oriented with its head in the same direction as hair tips of that site on the host. Horn flies typically have eyes that are dark reddish-brown.
Egg laying, habitat and feeding
The horn fly lays eggs in fresh cow manure, and the female is known to lay her eggs in the feces before the cow has even completed defecation.The larva
Larva
A larva 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...
e remain in fresh pats of the animal's dung and feed on both the resident bacterium and the compositions of the decomposition products of the resident bacterium.
The adult will finds a suitable host and remains on it and others in the same herd for life, with the female only leaving to lay her eggs. Horn flies will also move around to different areas on the same animal to regulate their temperature and minimize their exposure to the wind. Both the male and the female subsist completely on blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
, using their sharp mouthparts to pierce the animal's hide to suck it out.
Males typically feed around 20 times and females around 40 times daily, and when not feeding they tend to rest around the horn region of the host.
Stages of development
The horn fly undergoes complete metamorphosis, and has four major stages of development:The first stage is the egg, which is laid in fresh feces, and hatches quickly. The resulting larval (maggot
Maggot
In everyday speech the word maggot means the larva of a fly ; it is applied in particular to the larvae of Brachyceran flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and Crane flies...
) stage, which consists of three larval instars (wingless), develops quickly and can last as little as four days. This is followed by the still immature pupa stage (also wingless) which lasts around six to eight days and finally the mature, winged adult stage.
Generational time may be as little as ten days under ideal conditions, but under less favorable circumstances can average between 14 to 18 days.
Danger to livestock
The horn fly, as can be gleaned from its taxonomic designation Haematobia irritans, is an irritant to livestock. Beyond this, incessant biting is compounded by loss of blood, and results in such detrimental effects on host physiology as to include reduction in milk production, efficiency, and rate of gain. If the host is infested with a large number of flies, the resulting skin irritation and wounds may result in the drawing of a secondary infestation of myasis producing flies. There is some controversy over whether the horn fly is a disease vector, with at least one source asserting that the flies can be an intermediate host of Stephanofilaria stilesi, a parasite of cattle in North America.Domestic animals affected
Primarily livestock (specifically cattle) but is known to feed on horses, sheep and goats, albeit to a lesser extent.Range
The horn fly is known as a strong flier, and upon emerging as adults they can fly up to 10 miles to find a host. However, most often a horn fly will not have to fly more than three miles to find a host.Seasonality and locality
Found primarily in and around the states surrounding KansasKansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
. Haematobia irritans is not native to the U.S. and originally came from Europe. It can live in any similarly climatized area, as evidenced by its most recent spread to Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
and Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
. In the U.S., the active time of the horn fly is between April and October and, in a warm fall, even as late as mid-November. The flies are often most abundant from June through mid-July with a second population peak in mid-to-late August.
Management
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
matrix impregnated with pyrethroid
Pyrethroid
A pyrethroid is an organic compound similar to the natural pyrethrins produced by the flowers of pyrethrums . Pyrethroids now constitute a major commercial household insecticides...
, and can be effective for between 16 to 24 weeks. Originally, the ear tags were developed and used against such pests as tick
Tick
Ticks are small arachnids in the order Ixodida, along with mites, constitute the subclass Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians...
s and by 1983 50% of cattle had ear tags. Long periods of such dosing resulted in the elimination of 95-99% of susceptible flies, but this strong selection pressure ended up resulting in the development of resistant strains of the flies. To combat this, the use of organophosphate
Organophosphate
An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactors that are essential for life...
s and piperonyl butoxide
Piperonyl butoxide
Piperonyl butoxide is an organic compound used as pesticide synergist, especially for pyrethroids and rotenone. It does not by itself have pesticidal properties. However, when added to insecticide mixtures, typically pyrethrin, pyrethroid, and carbamate insecticides, their potency is increased...
as a synergist
Synergy
Synergy may be defined as two or more things functioning together to produce a result not independently obtainable.The term synergy comes from the Greek word from , , meaning "working together".-Definitions and usages:...
are now recommended to be alternated with pyrethroid to help slow resistance. In addition, methoprene
Methoprene
Methoprene is a juvenile hormone analog which can be used as an insecticide that acts as a growth regulator. Methoprene is an amber-colored liquid with a faint fruity odor which is essentially nontoxic to humans when ingested or inhaled. It is used in drinking water cisterns to control mosquitoes...
in the form of sustained release bolus (a rounded mass of food or pharmaceutical preparation ready to swallow) inhibits the emergence of an adult insect from a pupal case or an insect larvaa from an egg for up to 7 months.
New research (2011) has shown essential oil vapors from 16 species of Eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
to have toxicity against Haematobia irritans.
Mutations and known variations
A white-eyed "albino" horn fly was discovered in a colony maintained at the Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, TexasKerrville, Texas
Kerrville is a city in Kerr County, Texas, United States. The population was 20,425 at the 2000 census. In 2009, the population was 22,826...
. This is apparently a spontaneous mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
, as tests including crosses were performed that determined the white-eye mutation was not sex-linked
Sex linkage
Sex linkage is the phenotypic expression of an allele related to the chromosomal sex of the individual. This mode of inheritance is in contrast to the inheritance of traits on autosomal chromosomes, where both sexes have the same probability of inheritance...
and the white-eyed flies actually have decreased amounts of eye pigment present within the head. This appears to be an inherited simple Mendelian
Mendelian inheritance
Mendelian inheritance is a scientific description of how hereditary characteristics are passed from parent organisms to their offspring; it underlies much of genetics...
autosomal recessive
Dominance relationship
Dominance in genetics is a relationship between two variant forms of a single gene, in which one allele masks the effect of the other in influencing some trait. In the simplest case, if a gene exists in two allelic forms , three combinations of alleles are possible: AA, AB, and BB...
with complete penetrance
Penetrance
Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also express an associated trait . In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation who exhibit clinical symptoms...
. A colony of white-eyed horn flies was established from this single individual and has been maintained in the laboratory as visible genetic markers such as an eye color mutation in an economically important species like the horn fly may be useful for behavior and population dynamic studies, as well as release and recapture studies. No other differences from the wild-type flies were detected in the external characteristics of the mutant phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
or in egg viability. However, white-eyed flies had significantly lower amounts of the pigment dihydroxyxanthommatin in their heads suggesting either the lack of xanthommatin production, or a failure of transport and storage within the head of the mutant phenotype.
External links
- Haematobia irritans irritans on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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