Pasture flies thrive due to hot and humid weather

Dairy Veterinarian Scott Poock from the University of Missouri states that there are three types of flies that cause damage and economic discomfort in cattle. Horn flies, face flies and stable flies tend to appear in Spring, but due to the hot and humid weather they have carried on into the summer months.

Scott has said “The warmer it is, the faster the fly goes through its life cycle. In a given summer, several generations can turn over as they multiply.”

It is recommended by Mr Poock that monitoring cattle is important as this ensures important management decisions are made. Making sure you make important decisions reduces losses and improves overall health of the herd. A reduction in weight gain and lessened milk production both result in losses.  Illnesses such as pinkeye and mastitis can also result in a loss.

Adult flies are just the tip of the iceberg. Noticing a build-up of adult flies means they are breeding and multiplying at a rapid rate. Finding the source is imperative to achieve full eradication of them.

Stable flies attack the legs of cattle by biting and feeding on their blood. This causes the animal to swish its tail and stomp its feet as it is extremely uncomfortable. After the female stable fly has finished feeding, she will lay her eggs in manure. It is advised to keep pastures mowed and feeding points dry to reduce the likelihood of the flies breeding.

Horn flies will gather on the back of cattle in masses, and when the weather warms up they travel to the belly. The female horn fly will live most of their lives on the cow, only moving to lay their eggs in manure. The flies cause discomfort to cattle due to their bites as they suck their blood. The life cycle of the fly is complete between 10 and 20 days when it is warm.

Face flies are a non-biting insect and are prevalent in July and August. They cluster around animals eyes, mouth, and muzzle. They also gather around wounds, but fortunately do not stay there for long periods of time. Instead, they spend most of their time along waterways and on other objects which can make control difficult.

It has been proven that insecticides are the best and most effective way to treat horn flies. Treatments include dust bags, back rubbers, pour-ons, insecticide-impregnated ear tags and insect growth regulators. Scott Poock has also recommended that rotating treatments can deliver better results.

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