Consider the variables in fly control

As weather becomes warmer, it's a good time to focus on preventing the problems flies cause for cattle and optimum production goals. During certain times of the year, flies can be very costly to a dairy replacement operation by decreasing feed intake. Controlling flies and their effects can be difficult, and prevention and appropriate treatment depends upon which fly species causes the irritation.

Here are the most common irritating flies:

Horn flies (Haematobia irritans) -- These flies spend most of their time on the animal and take 20 to 30 blood meals a day. They often point their heads toward the ground -- giving them a "V" appearance, as they lay eggs in fresh manure.

House flies (Musca domestica) -- House flies spend their time feeding on decaying organic matter and spoiled feed. They usually lay eggs in rotting organic matter, such as old hay or manure. This species causes only mild irritation.

Stable flies (Stomoxys calcitrans) -- These flies take 2 to 3 painful blood meals per day, usually on the legs of cattle. After, they rest in trees and shade. The painful bites will cause cattle to bunch up, stomp and kick.

Face flies (Musca autumnalis) -- Face flies spend most of their time around the mouth and eyes and feed on tears and saliva with their sucking mouth parts. They irritate and can spread the organism that causes pinkeye.

Best management practices include:

For flies that spend most of their time on the host, such as horn flies and face flies, ear tags can be a good solution. Ear tags have a limited lifespan, so most people recommend waiting to attach during fly season. Rotating between organophosphate- and pyrethrin-based ear tags will slow fly resistance to the chemicals.

Pour-on fly control can help protect against all species, but this treatment is labor intensive and must be often repeated.

Insect growth regulators (IGRs) in feed rations prevent horn fly development in manure. IGRs must be fed throughout the fly season and should not be expected to provide complete control.

Environmental control can be effective to control house fly populations by reducing their nesting environment.

Other options include parasitic wasps, back rubbers and traps.

The best fly control strategy varies by geographical location, rainfall, stocking density and management. Producers typically need several different types of fly control throughout the season.

Always consult with your veterinarian for specific recommendations for your operation.

Source: Dairy Calf & Heifer Association  

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