Parasitic flies of domestic animals

These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high.

Feeding by adult flies may cause irritation through acute stress from painful bites, resulting in loss of grazing time and reduced gain in weight.

All species of veterinary and medical importance are blood feeders, with various types of mouthparts (these variations do not relate clearly to dipteran taxonomy).

Biting stress can be severe in varied climatic regions (cold northern or tropics) or conditions of much surface water available for breeding where populations of mosquitoes can become dense.

(Mosquitoes are of major importance as transmitters of many types of pathogenic microorganisms to humans causing diseases such as malaria and yellow fever.

Typical genera are Culicoides and Leptoconops (the term "midge" is also used for dipteran flies that are harmless to domestic animals such as those also known as lake-flies (Chironomidae).

Mouthparts are relatively short and complex with three pairs of cutting or slashing elements that create a superficial wound from which blood is imbibed.

Horses suffer from a cutaneous hypersensitivity reaction called sweet-itch, or Queensland-itch that is caused by antigenic components of saliva of biting midges.

Sandflies are like small versions of mosquitoes, but also with overall furry appearance from many long setae (like hairs) on body and wings (see photograph of Phlebotomus pappatasi).

Many species of brachyceran flies such as the house-flies and blow-flies that do not feed on blood are also mechanical transmitters of pathogenic organisms by a contaminative route on their mouthparts used for sponging up wet nutritious secretions on skin of vertebrate animals.

Tabanid flies have large mouthparts comprising three pairs of cutting / slashing elements that pierce skin in a superficial wound.

Dense populations of these flies cause severe biting stress to livestock and horses leading to reduction of gain in liveweight.

Many genera of tabanid flies transmit the protozoan Trypanosoma evansi that causes in camels and horses the disease called surra.

[7] Some species of this type, such as Musca vestustissima (Australian bush-fly) also have, as part of this sponge structure, small teeth that can scrape at host's skin down to superficial capillaries to feed on blood.

Species within the genera Stomoxys stable-flies, and Haematobia horn-flies are highly adapted for blood feeding, having mouthparts consisting of a strong projecting labium with cutting elements at its point.

[35] Irritation is caused by large numbers of Musca house-flies, through to severe biting stress from dense populations of Stomoxys or Haematobia flies.

[37] The feeding of various Musca species of fly permits the contaminative transmission of nematode worms, for example Parafilaria bovicola, causing a nodular filariasis in cattle.

Haematobia horn-flies transmit nematode worms in the genus Stephanofilaria to the skin of cattle, causing stephanofilariasis, a suppurating dermatitis known as hump sore.

In genera such as Calliphora and Lucilia the females lay their eggs on the same dead animal material and the larvae feed their by rasping at the muscle and other tissues with their mouthparts.

[43][44] Females of Chrysomya, Cochliomyia and Wohlfahrtia and similar genera always seek out their host such as cattle, sheep, dogs, to lay their eggs at vulnerable sites such as a small wound.

All species of the Oestridae are so highly adapted to the myiasis type of parasitism that the adults do not feed and have only residual mouthparts (see photograph of Hypoderma iparece).

With infestations of warble-flies and nasal-bots severe distress to the hosts may be caused and there are production losses from reduction of value of cattle hides, and reduced grazing time by sheep.

These usually consist of netting made of synthetic fibers or fine metal mesh that is fitted to the ventilation slats or windows of housing for livestock animals.

The fiber netting can be impregnated with insecticides such as the synthetic pyrethroid deltamethrin that acts rapidly when flies such as Stomoxys or Glossina species land on it.

[55] Valuable horses in areas infested with Culicoides midges or Simulium black-flies can be protected with commercially available shields made of cloth that fit over head, neck and back.

However, for many types of dipteran flies, the larvae inhabit areas such as bogs (Culicoides), swamps (mosquitoes), or rivers (Simulium) that are impractical to treat under typical commercial constraints within agriculture.

Typically various types of synthetic pyrethroids such as deltamethrin, cypermethrin, and permethrin are formulated in an oil or watery suspension suitable for application direct to the skin of animals at risk.

[57] In addition, to protect against flies such as Stomoxys and Glossina species that feed on legs and belly the insecticide can be sprayed selectively to those regions.

Also, cattle can be treated using self-applicators such as back-rubbers made of large bundles of fiber impregnated with the insecticide, or in automatic walk-through sprayers.

[64] Infections with nematode worms causing filariosis may be treated with the avermectin class of biologically derived drugs (macrocyclic lactones) such as ivermectin, doramectin, moxidectin.