Since the flies remain on the animal for long periods of time, control of the adult is simplified. The application of suitable insecticide throughout the horn fly season provides effective control. When economical, the spreading of fresh droppings to hasten drying also aids in disrupting the life cycle of the horn fly.
Reduced weight gain due to horn flies may be attributed to energy expended combatting flies, reduced food intake while combatting flies and to altered grazing behavior due to fly irritation.
A number of labor-saving self-treatment devices may be employed to control horn flies. Self-treatment commonly used includes backrubbers, oilers, dust bags and insecticide impregnated ear tags.
Backrubbers and Oilers
Backrubbers and oilers will provide good horn fly control if properly placed and maintained. Loafing areas around water sources or shade areas are often choice locations for positioning these self-treatments to encourage maximum usage.
Dust Bags
Control of horn fly populations can be achieved by the effective use of dust bags. Many good, durable bags are available commercially. Fly control with dust bags can be greatly enhanced by forcing animals to pass through dusting stations. A gate between a pasture and water source is a good example.
lnsecticide Ear Tags
Many brands of insecticide impregnated ear tags are presently registered for and provide excellent horn fly control. Apply the tags as recommended by the manufacturer.
Resistance of flies to ear tags can become a problem if they are overused or not used properly. It is suggested that pyrethroid ear tags be alternated with organophosphate ear tags or other methods of control on a year-to-year schedule to be determined by the producer. Your county Extension office can provide more information on correct usage of ear tags to avoid onset of resistance.
Other Treatment Considerations
Several other methods of control may, under certain conditions, provide some horn fly control. Among these are oral larvicides and livestock sprays.
Future horn fly control may involve a multifaceted approach for managing the pest population. Knowledge is currently being accumulated on behavior, genetics, physiology and ecology of horn flies. Naturally occurring parasites, predators, fly attractants and feeding stimulants are known for the horn fly. Research being conducted at the University of Arkansas has shown that resistance to horn fly infestation is heritable in beef cattle.
For information concerning which insecticides to use and how to use them correctly for beef cattle external parasite control, contact your county Cooperative Extension Service office.
Source: DR. DONALD R. JOHNSON, Extension entomologist, and DR. GUS LORENZ, Extension entomologist - IPM coordinator, are with the Cooperative Extension Service, University of Arkansas, Little Rock.