Fly Control Program - IGR or Cattle Rubs

Producer Question from 2012

Q:  What do you recommend for a fly control program for yearlings on pasture this summer? What is your opinion of the IGR mineral or cattle rubs? (June 15, 2012)

For current information, please see the "Fly Control for Cattle on Pasture in Nebraska" (May 2016) article.

A:  There are many different fly control products available for cattle producers to use. The key to fly control is to apply it on a timely basis and don't use the same active ingredient for more than two years in a row. The reason for this is that flies will become resistant to the active ingredient if used over and over again.

I see producers put a fly tag in way to early because of convenience when there are no or few flies and then have no control later in the season. If you are using fly tags, put them in a week to 10 days before the fly season starts. I know this is a guess – but in Nebraska, we usually don't have fly problems in April. If fly problems are bad, it may mean you put a tag in the cow and calf.

Sprays and oilers are effective as well. If you use an oiler, make sure the height is so calves can also use it. Not all oilers are built the same, so check construction.

IGR products are insect growth regulators and they control flies at the site the eggs are deposited – manure. Face flies and horn flies lay their eggs in cow manure and the larvae only develop in cow manure.

Therefore, some of the compounds that are fed or given in bolus form kill the larvae in the manure pat. Examples of this include the slow release bolus with diflubenzuron (Vilgilanteâ). This compound is an insect growth regulator (IGR), which is safe, and cross-resistance does not develop. Another IGR that is used in feed through products is methoprene. Other products are available that can kill the fly larvae when used as a feed through.

Flies do travel some distances, so you may use these products and still have flies that come from your neighboring pastures. If your neighbors use an IGR, then you potentially will have fewer flies.

Dr. Rick Rasby, Professor of Animal Science
Animal Science, University of Nebraska–Lincoln, Lincoln, NE