''Haematobia irritans'', the horn fly, is a small
fly
Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwing ...
(about half the size of a
common housefly). It was
first described by
Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
in his 1758
10th edition of ''Systema Naturae''. It is of the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Haematobia
''Haematobia'' is a genus of biting true flies of the family Muscidae.
Species
*'' H. exigua'' Meijere, 1906
*'' H. irritans'' (Linnaeus, 1758)
*'' H. minuta'' ( Bezzi, 1892)
*'' H. potans'' ( Bezzi, 1907)
*'' H. schillingsi'' ( Grünberg, 190 ...
'' which is the European 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.
Appearance
''H. irritans'' is the smallest of the biting
muscids, 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
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
, 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
Cow dung, also known as cow pats, cow pies or cow manure, is the waste product (faeces) of bovine animal species. These species include domestic cattle ("cows"), bison ("buffalo"), yak, and water buffalo. Cow dung is the undigested resid ...
, and the female is known to lay her eggs in the feces before the cow has even completed defecation.
The
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.
The ...
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 find 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 is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
, 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
gut microbiome
Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut mic ...
has been investigated. Palavesam et al 2012 uses
next generation sequencing
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. The ...
to specify the
symbiotic
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
species helping ''H. irritans'' to digest bloodmeals.
Stages of development
The horn fly undergoes
complete metamorphosis
Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the superorder Endopterygota. ...
, 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
A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera 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
instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
s (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 10 days under ideal conditions, but under less favorable circumstances can average between 14 and 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) are affected, but it 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
Kansas
Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...
. ''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 (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
and
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
. 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
Fly control tactics are moving away from dependence on pesticides, due to concern for the environment and pests developing resistance to insecticides. The first line of defense involves reducing the horn flies ability to reproduce.
["Outsmarting Flies On the Ranch"](_blank)
/ref> Manure and wasted hay can be spread thinly for quick drying, or composted. Composting techniques must allow for the entire mass to reach temperatures that will kill insect eggs (e.g. the Berkley method).
Rotating hens three days behind cattle is an effective method in reducing horn fly populations by scratching apart their habitat as they eat the horn fly larvae. The horn fly eggs take 1 to 2 days to hatch.
The tree swallow (''Tachycineta bicolor
The tree swallow (''Tachycineta bicolor'') is a migratory bird of the family Hirundinidae. Found in the Americas, the tree swallow was first described in 1807 by French ornithologist Louis Vieillot as ''Hirundo bicolor''. It has since been move ...
'') is also an effective predator of ''Haematobia irritans'' and can be attracted by building tree-swallow houses spaced approximately 100 feet apart. Each adult tree swallow will consume about 2,000 insects per day during an average 45 day nesting period. The parents also catch and feed their brood (of 4-7 nestlings) about 6,000 insects per day during an average 20 days spent inside the nestbox.
Parasitic wasps
Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causin ...
can reduce fly larvae by 90%. Put out enough wasps to inhibit what's left and put out more wasps every 30 days through summer.
Dung beetle
Dung beetles are beetles that feed on feces. Some species of dung beetles can bury dung 250 times their own mass in one night.
Many dung beetles, known as ''rollers'', roll dung into round balls, which are used as a food source or breeding cha ...
s spend their lives in manure. Adults use liquid components as nourishment and lay eggs in the manure pat. The hatching larvae consume manure. Some species remove and bury balls of manure containing their eggs. An active population of dung beetles can bury or destroy 95% of horn fly eggs and larvae and about 90% of other cattle parasites that are passed in or depend on manure. Even if the fly eggs hatch in the manure balls, they can't get back up to the ground surface after being buried by the dung beetles. What's more, birds are attracted to manure containing dung beetles and tear the pats apart to eat them. This helps spread manure and disrupt fly-larvae development. A single manure pat without dung beetles can generate 60-80 adult horn flies.
Chemical methods have included 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 tag
An ear tag is a plastic or metal object used for identification of domestic livestock and other animals. If the ear tag uses Radio Frequency Identification Device (RFID) technology it is referred to as an electronic ear tag. Electronic ear tags ...
s on cattle has been extremely successful. The ear tags are made of a PVC matrix impregnated with pyrethroid
A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and ''Chrysanthemum coccineum, C. coccineum''). Pyrethroids are used as commercial and hou ...
, and can be effective for between 16 and 24 weeks. Originally, the ear tags were developed and used against such pests as 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 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 selective pressure ended up resulting in the development of resistant strains of the flies. To combat this, the use of organophosphate
In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered a ...
s and piperonyl butoxide
Piperonyl butoxide (PBO) is a pale yellow to light brown liquidNational Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Tr ...
as a synergist are now recommended to be alternated with pyrethroid to help slow resistance. In addition, methoprene
Methoprene is a juvenile hormone (JH) analog which acts as a growth regulator when used as an insecticide. It is an amber-colored liquid with a faint fruity odor.
Methoprene does not kill insects. Instead, it interferes with an insect’s life ...
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 larva from an egg for up to 7 months.
New research (2011) has shown essential oil vapors from 16 species of eucalyptus
''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...
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, Texas
Kerrville is a city in, and the county seat of, Kerr County, Texas, Kerr County, Texas, United States. The population of Kerrville was 24,278 at the 2020 United States Census, 2020 census. Kerrville is named after James Kerr (Texas politi ...
. This is apparently a spontaneous mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...
, as tests including crosses were performed that determined the white-eye mutation was not sex-linked
Sex linked describes the sex-specific patterns of inheritance and presentation when a gene mutation (allele) is present on a sex chromosome (allosome) rather than a non-sex chromosome ( autosome). In humans, these are termed X-linked recessive, ...
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 (also known as Mendelism) is a type of biology, biological Heredity, inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, an ...
autosomal recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
with complete penetrance
Penetrance in genetics is the proportion of individuals carrying a particular variant (or allele) of a gene (the genotype) that also express an associated trait (the phenotype). In medical genetics, the penetrance of a disease-causing mutation is t ...
. 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
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...
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.
Genomics
The insecticide susceptible Kerrville reference strain horn fly genome was assembled by the USDA-ARS Knipling-Bushland US Livestock Insects Research Laboratory in 2018.[ ] The assembled size of the horn fly genome is 1.14 Gb which was close to previously published estimates using flow cytometry (1.2 Gb). This makes the horn fly genome larger than the genome sizes of the related ''Muscidae'' flies ''Musca domestica'' and ''Stomoxys calcitrans'', which were reported as 1.0 Gb and 1.1 Gb.[ ] In addition to the nuclear genome of the Kerrville reference strain, the maternally inherited endosymbiont ''Wolbachia pipientis'' ''w''Irr has also been assembled.[ ]
References
Notes
Kansas State Research and Information
*
*
External links
on the UF / IFAS IFAS may refer:
* Institute of Food and Agricultural Sciences
* Integrated Fixed-Film Activated Sludge, a sewage treatment process
* International French adjectival system
In rock climbing, mountaineering, and other climbing disciplines, clim ...
Featured Creatures Web site
{{Taxonbar , from=Q3125657
Muscidae
Veterinary entomology
Insects described in 1758
Insects in culture
Taxa named by Carl Linnaeus