– Steve Boyles, OSU Beef Extension Specialist
Horn Fly: The horn fly is the major insect pest on pasture cattle and is less often found around farmsteads. They deposit their eggs in fresh manure, usually within minutes after the manure is dropped. Horn fly eggs hatch and reach the adult stage in about 10 to 14 days. They pass the winter in the pupal stage with the first of the season’s adults emerging and moving to the livestock about mid-May. Horn flies have blood sucking mouthparts and usually take several blood meals per day. These flies roost on cattle.
Face Fly: The face fly looks like the house fly and has sponging-type mouthparts. It prefers to be in the sun and seldom enters barns or shady areas. Face flies breed in fresh manure. They overwinter as adults and are usually the first flies seen in the spring. Face flies feed on the mucous membranes of the eyes, nose and mouth of and in addition play a role in the transmission of pink eye.
House Fly: Around barnyards, house fly populations can reach very high levels during the summer months. House flies breed in rotting plant or animal material and manure. Barnyard sanitation in controlling these flies. The winter is passed in the pupal stage in barnyard litter. House flies, like the face fly, have sponging-type mouthparts and feed on livestock secretions and moisture in the manure.
Stable Fly: The stable fly (sometimes called the biting house fly) is similar in appearance and habitat preference to the house fly but has piercing-sucking mouthparts. Like the house fly, the stable fly breeds in decaying organic matter of many types. The stable fly, like the housefly and horn fly passes the winter in the pupal stage.
Insect Control: When using any insecticide, workers must always read and follow label directions. Effective control of livestock insects can be obtained through timely treatment with approved insecticides used in conjunction with thorough barnyard sanitation. High fly population may require a combination of control methods.
Backrubbers, Oilers, and Dust Bags: Backrubbers and oilers will provide some reduction in face fly numbers but are generally not as good for controlling face flies as they are for horn flies. Models that force the animal to get the toxicant around the head area are generally best for reducing face fly numbers. Backrubbers offer cattle the incentive to satisfy their instinct to scratch and are most effective if placed in pasture areas where livestock loaf. Reductions In face fly and hom fly populations can be achieved by the effective use of dust bags.
Spraying: Routinely spraying cattle with insecticide sprays can be effective for horn fly control, but requires labor. Most insecticides available in spray formulations last only 1 to 2 weeks, and cattle need to be handled and brought into a confined area to be sprayed.
Ear Tags: There are numerous trade names and designs currently marketed containing pyrethroid, organophospate, and avermectin insecticides. Depending on the product, one or two tags are installed per animal. Ear tags containing pyrethroids provide excellent control of horn flies and face flies. However, horn flies have developed some resistance to these pyrethroids. The organophosphate tags available will control pyrethroid-resistant horn flies. Ear tags release insecticide most efficiently during the first two months after application. Remove the tags at end of the fly season.
Pour-on: Pour-on is applied from the head down to the tail. Where pyrethroid-resistant horn flies are present, a non-pyrethroid-resistant pour-on should be used.
Oral Methods: Boluses prevent immature fly larvae from becoming adults. Another means of oral treatment is the use of larvicide feed additives in free-choice in mineral.
Biological control: Dung beetles can be of benefit by aiding in the destruction of manure piles. Managing pasture flies and promoting dung beetles is a delicate balancing act. If there has been the extensive use of certain dewormers and systemic insecticides, the residues from them may kill dung beetles. If you find holes in the surface of the manure piles, or piles appear to be shredded, you probably have dung beetles. To confirm their presence, open the piles look for adult beetles.