Occurrence: Most problematic in northern temperate zone and subarctic, but some important species are found in tropics.
Species affected: All.
Age affected: All.
Causes: Blackflies (family Simuliidae) are also known as turkey or buffalo gnats are blood-sucking insects.
Effects: Can cause serious damage to humans and livestock, and in dense numbers can cause unthriftiness and anaemia. They also transmit blood protozoan parasites such as leucocytozoon, causing avian malaria.
Blackflies (family Simuliidae) are also know as turkey or buffalo gnats. They are similar in size to mosquitoes but are dark, short, chunky, and humpbacked, with short legs; wing venation is distinctive. More than 20 species have been reported to attack domestic poultry in North America. Blackflies usually suck blood during the day and may cause serious damage to people and livestock; in dense numbers they may cause a severe anemia in poultry. They also transmit certain blood protozoans belonging to the genus Leucocytozoon.
Blackfly production sources are restricted to running water such as creeks, streams, or irrigation supply and drainage systems. Eggs are laid on rocks, sticks, or floating vegetation, or are dropped into streams. They may hatch in a few days, but some remain through summer or even until the following spring. Larvae attach to stones or other objects and reach the pupal stage after 3-10 weeks. The pupal stage also occurs under water, lasting from a few days to 1 week or more. Adults or some species emerge in spring, others during summer or early fall. Overwintering occurs in the egg or larval stage. Most temperate-zone species have one generation per year.
Blackflies can cause serious damage to humans and livestock, and in dense numbers can cause unthriftiness and anaemia. As blackflies are active during the day, they may be seen on birds or in the house.
Signs of anaemia and / or unthriftiness may indicate a heavy infestation with a number of parasites. Blackflies should be distinguished from mosquitoes or houseflies.
Treatment and control:
Control is difficult because these pests develop in streams, often some distance from the poultry farm, where insecticide treatment may be harmful to fish. Successful reduction of larval and subsequent adult blackfly populations, without fish kills, were obtained in infested streams treated monthly by helicopters using 2% temphos granules. Area-wide control programs have been developed using biological control agents such as Bacillus thuringiensis var. israelenis (Bti). These programs involved weekly treatment of all breeding areas in defined geographical areas. Measures recommended for mosquito control, as well as cautions on watershed contamination by pesticides, are also pertinent to blackfly control.
- The synthetic and natural pyrethroid insecticides, organophorus, and carbamate are the main ectoparasite and fly control chemicals used for direct application to poultry, litter, or buildings. In general, chemical insecticides and disinfectants should not be mixed for application together.
- Among the botanical insecticides, pyrethrum remains very effective against flies and is a main ingredient of mist and aerosol fly sprays, particularly with synergists.
- The chlorinated hydrocarbon insecticides are banned from use on poultry or in poultry houses because of residues in eggs and meat. Under no circumstances should DDT, benzene hexachloride, toxaphene, chlordane, aldrin, dieldrin, endrin, or heptachlor be used on poultry houses or on poultry feed or feed ingredients.
- Insecticides are available as wettable powders (WP), emulsifiable concentrates (EC), and water dispersible liquids (WDL), all of which are intended to be applied as a spray or mist. Insecticides are also available as dust and as baits. These low-assay products are prepared, premixed, and ready to use. Care should be taken to ensure that feed and water are not contaminated and that all label directions are strictly adhered to so that tolerances are not exceeded.
- Apply the insecticide directly where the pest is located. If birds are being sprayed, the treatment must thoroughly cover the entire bird and the bird should be wet to the skin. If buildings are being treated, the sites where the pests are located must be treated if control is to be adequate. Methods for caged layers include high-pressure sprays of 125 pounds per square inch (psi) from outside the cages. Other treatments are:
- Dusting. For conventional houses, apply to litter; attempt to cover the area evenly including under roosts, feeders and nest boxes.
- Spraying. The usual cylindric compressed-air sprayers are satisfactory for treating roosts and walls, as are knapsack sprayers (continuously pumped during spraying) that give a continuous spray. Sprayers powered by an electric or gasoline motor that delivers pressures of 125 psi, and use of a spray gun with a solid-stream nozzle are much more rapid and efficient. When spraying houses, high-pressure and large-volume output are most desirable to drive spray into all cracks and crevices.
- Misting. Electric mist machines (foggers) are efficient, rapid, and often labour saving. Mist machines are concentrate applicators and do not use the same mixtures as ordinary sprayers. Generally they use 5-10 times the concentration and 1/3–1/10 the volume. In all fog work, the container should be shaken frequently during spraying to keep insecticide from settling. Mist machines can be used efficiently to dispense fly spray.