Horn Flies on Cattle
Are your cattle constantly swatting or bunching up? The culprit is most likely the Horn Fly. Unfortunately for cattle producers, with all our good rainfall this appears to be a good year for the Horn Fly.
I see very few herds that are not infested to some degree with Horn flies.
The good April and May moisture seems to have helped the population grow.
Where do they all come from? Horn fly eggs are laid exclusively under the edges of fresh manure, minutes after defecation. The larvae develop for 1-2 weeks in the manure before pupating in dry soil.
Horn flies’ diapause as pupa in temperate latitudes, which means they spend the winter as pupa to increase survival.
Those hay feeding areas where manure tends to accumulate are prefect Horn Fly nurseries. Minimize manure accumulation by spreading and breaking manure piles so that they dry faster and become unsuitable for larval development.
Also, rotating pastures and hay feeding areas allows for less manure and residual hay accumulation in one area.
The adult horn fly is 3-5 mm long with piercing/sucking mouthparts that are painful to cattle. The adult horn flies stay in continual contact with the cattle, resting on them between feedings.
They can be seen on the withers, back, and side of the cattle and will move to the belly during the hottest parts of the day. Horn flies are the most significant pest of beef cattle and other pastured cattle, costing the industry an average of $1 billion annually in losses (this figure was determined before the current good cattle prices).
Both male and female horn flies are blood feeders that will take 20-30 meals (bites to an animal) per day. Depending on the infestation level, this can calculate to thousands of bites each day!
How and when to take control measures against Horn Flies? According to Texas A&M Veterinary Entomologist Dr. Sonja Swiger, Horn flies can be managed with many products; pour-ons, ear tags, feed thru products, dust bags, back rubbers, or sprays. Treatment should not be administered until at least 100 horn flies are present. Using just one strategy from the above list may not give you the results you anticipate.
Using a multifaceted approach from prevention through sanitation to combining treatment options is best for controlling Horn flies.