Haematobia irritans

Haematobia irritans, the horn fly, is a small fly (about half the size of a common housefly) described by Linnaeus in 1758. It is of the genus Haematobia 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.[1]

Haematobia irritans
Horn flies
Haematobia irritans on horse
Scientific classification
H. irritans
Binomial name
Haematobia irritans


H. irritans is the smallest of the biting muscids, gray in color, approximately ​316 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.[1]

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 larvae 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.

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) 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 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) but is known to feed on horses, sheep and goats, albeit to a lesser extent.


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. 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.


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 (https://www.beefmagazine.com/health/parasites/outsmarting-flies-on-ranch-0401). 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. Berkley Method https://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf).

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. http://entnemdept.ufl.edu/creatures/livestock/flies/horn_fly.htm).

Tree Swallow (14398630838)

The tree swallow (Tachycineta bicolor) is also an effective predator of Haematobia irritans and can be attracted by building tree-swallow houses spaced approximately 100' apart (http://www.treeswallowprojects.com/). 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. http://www.sialis.org/tres.htm

Parasitic wasps can be purchased from several suppliers. Such wasps can reduce fly larvae by 90% if you diligently reduce fly-breeding sites. Put out enough wasps to inhibit what's left and put out more wasps every 30 days through summer. https://www.beefmagazine.com/farm-life/7-ag-stories-you-might-have-missed-week-jan-18-2019

Dung Beetles 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 https://www.beefmagazine.com/health/parasites/outsmarting-flies-on-ranch-0401.

Insecticidal eartag
Insecticidal eartag

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 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 and 24 weeks. Originally, the ear tags were developed and used against such pests as ticks 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 organophosphates 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 larva 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.[2]

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. 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.


  1. ^ a b Gregor, F.; Rozkosny, R.; Bartak, M.; Vanhara, J. (2002). The Muscidae (Diptera) of Central Europe. Scientiarum Naturalium Universitatis Masarykianae Brunensis. 107. Masaryk.: Masaryk University. pp. 280pp.
  2. ^ Juan, LW; Lucia, A; Zerba, EN; Harrand, L; Marco, M; Masuh, HM (2011). "Chemical composition and fumigant toxicity of the essential oils from 16 species of Eucalyptus against Haematobia irritans (Diptera: Muscidae) adults". Journal of Economic Entomology. 104 (3): 1087–92. doi:10.1603/ec09431. PMID 21735933.


External links

Australian Dung Beetle Project

The Australian Dung Beetle Project (1965–1985), conceived and led by Dr George Bornemissza of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), was an international scientific research and biological control project with the primary goal to control the polluting effects of cattle dung.

Diptera in the 10th edition of Systema Naturae

In the 10th edition of Systema Naturae, Carl Linnaeus classified the arthropods, including insects, arachnids and crustaceans, among his class "Insecta". Insects with simply two wings (true flies) were brought together under the name Diptera.


Haematobia is a genus of biting true flies of the family Muscidae.

List of Diptera of Ireland

The number of species in the order Diptera (true flies) known to occur in Ireland is 3,304. There are 98 Dipteran families in Ireland For genera and species within the various Families, see Fauna Europaea.

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.

Red imported fire ant

The red imported fire ant (Solenopsis invicta), also known as the fire ant or RIFA, is a species of ant native to South America. A member of the genus Solenopsis in the subfamily Myrmicinae, it was described by Swiss entomologist Felix Santschi as a variant in 1916. Its current name invicta was given to the ant in 1972 as a separate species. However, the variant and species were the same ant, and the name was preserved due to its wide use. Though South American in origin, the red imported fire ant has been accidentally introduced in Australia, New Zealand, several Asian and Caribbean countries, and the United States. The red imported fire ant is polymorphic as workers appear in different shapes and sizes. The ant's colours are red and somewhat yellowish with a brown or black gaster. However, males are completely black. Red imported fire ants are dominant in altered areas and live in a wide variety of habitats. They can be found in rain forests, in disturbed areas, deserts, grasslands, alongside roads and buildings, and in electrical equipment. Colonies form large mounds constructed from dirt with no visible entrances because foraging tunnels are built and workers emerge far away from the nest.

These ants exhibit a wide variety of behaviours, such as building rafts when they sense that water levels are rising. They also show necrophoric behaviour, where nestmates discard scraps or dead ants on refuse piles outside the nest. Foraging takes place on warm or hot days, although they may remain outside at night. Workers communicate by a series of semiochemicals and pheromones which are used for recruitment, foraging, and defence. They are omnivores and eat dead mammals, arthropods, insects, seeds, and sweet substances such as honeydew from hemipteran insects with whom they have developed relationships. Predators include arachnids, birds and many insects including other ants, dragonflies, earwigs, and beetles. The ant is a host to parasites and to a number of pathogens, nematodes, and viruses which have been viewed as potential biological control agents. Nuptial flight occurs during the warm seasons, and the alates may mate for as long as 30 minutes. Colony founding can be done via a single queen or a group of queens, who will later contest for dominance once the first workers emerge. Workers can live for several months while queens can live for years; colony numbers can vary from 100,000 to 250,000 individuals. Two forms of society in the red imported fire ant exist: polygynous colonies (nests with multiple queens) and monogynous colonies (nests with one queen).

Venom plays an important role in the ant's life as it is used to capture prey or for defence. About 95% of the venom's components are water-insoluble piperidine alkaloids known as solenopsins, the rest containing a mixture of toxic proteins that can be particularly potent on sensitive humans. More than 14 million people are stung by them in the United States annually, where many are expected to develop allergies to the venom. Most victims experience intense burning and swelling, followed by the formation of sterile pustules, which may remain for several days. However 0.6% to 6.0% of people may suffer from anaphylaxis, which can be fatal if left untreated. Common symptoms include dizziness, chest pain, nausea, severe sweating, low blood pressure, loss of breath, and slurred speech. More than 80 deaths have been recorded from red imported fire ant attacks. Treatment depends on the symptoms; those who only experience pain and pustule formation require no medical attention, but those who suffer from anaphylaxis are given epinephrines. Whole body extract immunotherapy is used to treat victims and is regarded as highly effective.

The ant is viewed as a notorious pest, causing billions of dollars in damages annually and impacting wildlife. The ants thrive in urban areas, so their presence may deter outdoor activities. Nests can be built under structures such as pavements and foundations, which may cause structural problems, or cause them to collapse. Not only can they damage or destroy structures, but red imported fire ants also can damage equipment and infrastructure and impact business, land, and property values. As workers are attracted to electricity, they can swarm electrical equipment and destroy it. In agriculture, they can damage crops, damage machinery, and threaten pastures. They are known to invade a wide variety of crops, and mounds built on farmland may prevent harvesting. They also pose a threat to animals and livestock, capable of inflicting serious injury or killing them, especially weak or sick animals. Despite this, they may be beneficial because they consume common pest insects on crops. Common methods of controlling these ants include baiting and fumigation; other methods may be ineffective or dangerous. Due to its notoriety and importance, the ant has become one of the most studied insects on the planet, even rivalling the western honey bee (Apis mellifera).


Tc1/mariner is a class and superfamily of interspersed repeats DNA (Class II) transposons. The elements of this class are found in all animals, including humans. They can also be found in protists and bacteria.The class is named after its two best-studied members, the Tc1 transposon of Caenorhabditis elegans and the mariner transposon of Drosophila.

Veterinary parasitology

Veterinary parasitology is the study of animal parasites, especially relationships between parasites and animal hosts. Parasites of domestic animals, (livestock and pet animals), as well as wildlife animals are considered. Veterinary parasitologists study the genesis and development of parasitoses in animal hosts, as well as the taxonomy and systematics of parasites, including the morphology, life cycles, and living needs of parasites in the environment and in animal hosts. Using a variety of research methods, they diagnose, treat, and prevent animal parasitoses. Data obtained from parasitological research in animals helps in veterinary practice and improves animal breeding. The major goal of veterinary parasitology is to protect animals and improve their health, but because a number of animal parasites are transmitted to humans, veterinary parasitology is also important for public health.


This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.