Repellents applied to clothing have a long-lasting effect. Jackets impregnated with repellents are available commercially. Because repellents may be toxic to animals, humans, birds and fish, always read the instructions on the container before using repellents. Cattle Shelters, that provide dark conditions into which black flies will not fly are effective in providing cattle with relief from attack. Structures consisting of three solid walls and a roof are usually adequate.
Cattle quickly learn to use the shelters.
Self-application devices for repellents and insecticides can be installed to treat cattle as the enter or leave the shelter. Insecticide treatments must cover most of the animal's body to be effective. Only use repellents and insecticides specifically recommended for black flies and follow the label instructions carefully. Restrictions on use before slaughter or freshening must be followed. An electrostatic sprayer allows efficient application of repellents or insecticides to cattle under pasture conditions.