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News from your Extension Agent

Horn flies

Horn flies are the No. 1 pest of beef cattle in the U.S. They are obligate blood-feeding ectoparasites feeding almost exclusively on cattle. Horn flies weaken cattle in more ways than one. Not only do they suck blood, but their painful bites cause the cattle to react by tail swishing, head movement and general excessive movement of the animal. When an animal has approximately 250 flies or more on itself, it can lose 15-50 percent of its body weight. Losses in body weight decrease the producer’s paycheck by receiving less when that animal is sold or by having to purchase more feed to keep weight on the animal.

About horn flies: Horn flies look very similar to house and stable flies but are smaller. A horn fly has about a three-week lifespan, and in that time a female can lay several hundred eggs. The adult stage of the horn fly is spent on the animal, except for the few minutes it leaves to lay its eggs. Eggs are laid in fresh manure and take about 10-20 days to hatch and mature. As you can see, all it takes is one cow to stabilize this life cycle. Each fly feeds up to 40 times per day, adding to the stress of the animal. See Figure 1 for a fly comparison.

Horn fly control: Integrated pest management (IPM) is a good recommendation to follow. Integrated pest management takes in to consideration the cost of pesticides and animal loss, environment and health of the animal. An “integrated” approach means using more than one tactic to control flies. To utilize IPM, it is best to identify the pest correctly and understand the biology and life cycle of the pest. It is also recommended to rotate pesticides and management tools as a part of IPM. Management practices include: killing adult flies before they have a chance to produce offspring, excluding flies with screens or barriers, dragging pastures to level out manure and prevent buildup and to use other natural predators of flies. For example, certain beetles feed on horn fly larvae, dung beetles compete for space in manure. If biological control measures are not enough, chemical control measures may be necessary. In the Texas heat, chemical control measures are almost always necessary. When does a producer decide if chemicals are needed? There is a threshold level. Once flies reach 250 per side of the animal (remember at 250 flies per animal weight loss can occur) it is recommended to choose one or more of the following:

• Insecticide impregnated ear tags

• Sprays

• Pour-on liquids

• Back rubs

• Injections

• Insect growth regulators

• Mineral feed products

• Boluses

• Dust bags

Remember, the IPM approach includes utilizing two or more control methods. Depending on the severity of the flies it might be recommended to include protection for every animal in the form of an ear tag, injectable, or pour on liquid as well as provide a self-treatment device such as a dust bag, back rub or mineral product containing an insect growth regulator. The VetGun is a new tool available that allows a producer to treat animals at a distance without having to “work” the cattle. Each capsule contains a liquid fly repellent that works like a pour on treatment. Currently this is the only product of its kind.

Camp County is participating in a result demonstration to determine which has more efficacy and lasts longer? The VetGun capsules or insecticide impregnated ear tags. I will obtain research data throughout the summer and share the results in multiple formats from newspaper articles to social media posts and provide an informational program to producers as well.

All data and recommendations are based on Texas A&M AgriLife Extension Resources. No endorsements were made by using brand names or product names.

#AgFact

Economic losses due to horn flies in cattle can cost upwards of $1.36 billion for producers across the U.S. This is greater than any other losses caused by other insects.

Horn flies

The Pittsburg Gazette

112 Quitman
Pittsburg, TX 75686

Phone: 903-856-6629