DEET-Free Horn Fly Repellent

Horn flies are a pest of cattle, causing severe blood loss and decline in milk production.

Horn flies are small flies that usually attack cattle but may also attack sheep, goats, horses and dogs. They spend almost their whole life on their host animal, feeding on its blood between 20 and 40 times each day. Fortunately, they don't bite people. Although DEET is an extremely effective insecticide, it's been linked to various health problems, according to toxicologists at Cornell University Extension Toxicology Network.

Whole Animal Sprays

Sprays containing pyrethrums can be applied to cattle and other animals after removing dirt and dust from their coats. Whole-animal sprays are a fast way to relieve horn fly attacks. Brush the animal's hair while spraying on the insecticide until the surface of the hair is wet. Don't wash treated animals where there's runoff because pyrethrums are toxic to fish. Still, pyrethrums are considered a natural pesticide and are made from chrysanthemums and other related flowers.

Self-Applicating

Dust bags and back rubbers contain man-made insecticides like pyrethroids and organophosphates. Pyrethroids are similar to pyrethrums, and organophosphates are chemicals that disrupt an insect's nervous system. Back rubbers and dust bags are placed in areas of restricted movement, like gateways that the animals must pass through on their way to feed and water. When the animals make contact with them, the back rubbers and dust bags release insecticides that are very effective in controlling horn flies.

Feed Through

Insecticidal additives can be added to animal feed or mineral blocks to control horn fly larvae, but they have no effect on adult flies. Two types of additives are available. Insect growth regulators, including diflubenzuron and methoprene, prevent larvae from maturing into adults, and larvicides like tetraclorvinphos kill larvae.

Controlled Release

Ear tags containing insecticides like synthetic pyrethroids and organophosphates can be used to control horn flies for approximately 12 to 15 weeks by releasing small amounts of insecticides over a period of time. Unfortunately, some horn flies have developed a resistance to ear tags. Ear tags are more effective if you rotate chemicals rather than using the same one all the time.

Parasites

Horn flies can also be controlled by introducing parasitic wasps into your barn. These tiny wasps are the size of gnats. Although it's not possible to completely eliminate horn flies with parasites, they do reduce the amount of chemical pesticides needed for fly control. In addition, using parasites helps to keep horn flies from building up a tolerance to pesticides. The type of wasp to purchase varies, depending on where you live. Consult your local county extension for information about which species is right for your area. Other horn fly predators include dung beetles.

References

• British Columbia Ministry of Agriculture: Horn Fly
• Manitoba Prairie Pest Management; Mosquito and Fly Prevention and Control on Manitoba Farms; Roy Ellis; 2001/2002
• Ohio State University Livestock and Livestock Building Pest Management: Using Fly Parasites With Chemicals
• Cornell University Integrated Pest Management Extoxnet: Deet; October 1997
• Cornell University College of Agriculture and Life Sciences: Horn Flies
• University of Arkansas Division of Agriculture: Controlling Horn Flies on Cattle

Resources

• University of Florida Institute of Food and Agricultural Sciences Featured Creatures: Horn Fly
• Drugs.com: Equisect Fly Repellent