Gene McCluer, Extension Educator, Hardin County, The Ohio State University
Generally speaking, sanitation around the barn remains the backbone of fly control. Removal of potential breeding sites will slow the build-up of fly populations. Pyrethrins can be used in misters or foggers for quick knockdown of active fly problems, but they don't offer residual control. These include, but are not limited to, Pyrethrins+Piperonyl butoxide, Ectiban, and Vapona. These products can often be purchased in concentrates or in aerosol cans for use in milk rooms (or the pickup truck). Always read the label before using in livestock facilities.
Residual fly sprays can be used on walls, ceilings, posts, and other fly resting places. This type of product can have from 1 to 7 weeks of control. It may be necessary to remove the cows for 4 hours or until the spray dries. Usually, the manufacturer cautions that you not contaminate feed or water. See specific labels for application recommendations. Products for this use include, but are not limited to: Countdown 2 or Countdown 25% WP, Grenade 10% WP, Atroban 11%, Ecitban 5.7%, Permectrin II 10%, Spinosyn, and Elector. The same materials may be used on fly resting sites outdoors.
For pastured cattle and control of stable flies, face flies, and horn flies, ear tags, dust bags and back or face rubbers may have a place. Make sure the products are labeled for lactating cows, dry cows, or whatever type of animals that are being treated. Baits also can have a place in the fly control program. For more details, see University of Kentucky fact sheet ENT-42 at: http://www.uky.edu/Agriculture/PAT/recs/livestk/recbeef/beeffly.htm.
Other resources that are helpful include several lists of insecticide products at Kansas State University. The products are listed according to insecticides and common chemical names at: http://www.oznet.ksu.edu/entomology/extension/InsectInfo/ciiiiccn.pdf. They are also listed in alphabetical order at: http://www.oznet.ksu.edu/entomology/extension/InsectInfo/ciitrade.pdf, and by method of application at: http://www.oznet.ksu.edu/entomology/extension/InsectInfo/ciiiform.pdf.