Rather, they are found on heifers, dry cows, or lactating cows in operations where pasture forage is utilized as a major portion of their nutrient intake and the manure patty remains intact. The second type and most obvious fly found around the dairy is the house fly. Although houseflies do not consume blood or body fluid, they can transmit mastitis and threaten milking parlor sanitation. Control options for these two categories of pests vary slightly because of the location of egg deposition. Initiation of treatment early in the season may limit buildup.
Horn flies can actively fly or be moved by the wind for neighbor's cattle to have maximum effect.
Treatment for adult flies should begin when the fly count is greater than 200 per animal. Treatment prior to that time may not be cost effective and contribute to early insecticide resistance. Approved insecticides in the form of tags, sprays, or pour-ons can then be used to reduce the adult house fly or horn fly populations. If possible, rotation of products with different classes of insecticide is thought to reduce the speed at which resistance is developed. Other tools for fly control include premise sprays and parasitic wasps.