Fly Control

The hottest topic within the beef industry right now is fly control.   When confronted with a problem, most producers are quick to spend an inordinate amount of time, energy and money treating the symptoms – while they totally ignore the problem.   Folks, if we never work at solving the problem, we will never get rid of the problem – and it will continue to get worse.


I have always believed many of the problems we encounter in the cow-calf business have a genetic factor.   Genetic selection, though quite slow, can provide a long-term solution to many of our problems.   Horn flies are no exception.   It doesn’t take a genius to see that some cows have a fraction of the horn flies that other cows have.   For one reason or another, some animals have a genetic resistance to the dreaded horn fly.  


Dayton Steelman, a retired entomologist at the University of Arkansas, believes the heritability for fly resistance is 58% – which is very high.   With this in mind, I believe fly resistance is a trait all seedstock producers should be monitoring and selecting for.   Steelman studied horn flies and their effect on beef cattle for over fifteen years.   His research led him to the following conclusions:

  1. Some breeds, such as Brahman, are much more resistant to horn flies.   They have three times the number of hairs per unit of surface area than do most British and Continental breeds.
  2. Within a breed, some individuals are much more resistant to horn flies than others.
  3. Smaller framed animals have significantly fewer flies than larger framed animals within the same breed.   Cattle of the same breed seem to be born with approximately the same numbers of hairs.   When you enlarge the frame size, you have fewer hairs per square inch.   The bigger the animal, the greater the distance between hairs.
  4. Every hair follicle has two sebaceous glands that secrete a substance that reflects sunlight (heat) and provides a natural resistance to insects.   The more hairs, the more secretion.   Cattle that have a very slick and shiny summer hair coat seldom have much in the way of fly problems.
  5. Horn flies have an anti-coagulate factor in their saliva that prevents blood clotting while they are feeding.   Some beef animals have a higher level of a natural chemical called thrombin that works to counteract the fly’s anti-coagulate.   Simply by selecting for animals that have a higher level of thrombin in their blood, we can effectively select for horn fly resistance.
  6. Bulls, because of their testosterone, will typically have two to four times more flies than cows.   Flies are attracted to testosterone.


Bred-in parasite resistance is one of many areas in which Pharo Cattle Company has assumed the leadership position.   We want to continue to be “different for all the right reasons.”   We have evaluated and scored hair coat for many years.   We have been evaluating and scoring the bulls we sell for fly resistance for the last 10 years.   As Steelman suggested, there seems to be a relatively high correlation between hair coat score and fly resistance score.


Research has shown that horn flies can reduce daily gains by as much as ½ pound per day.   That could amount to 50 to 100 pounds per calf at weaning.   Do the math!   At $1.80 per pound, what’s a bull worth that can genetically improve the fly resistance of your herd?


Do you know of any other seedstock producers who evaluate and score their cattle for genetic fly resistance?   Most (if not all) use toxic chemical insecticides to cover up inferior genetics.   How is that going to help anyone?   The end result of using chemical insecticides is the creation of superior flies – and inferior cows.   Chemical insecticides are also responsible for killing a multitude of good bugs and organisms.   Dung beetles, for example, are nearly extinct on most farms and ranches.


Are you ready for a change?   Pharo Cattle Company represents the future in beef production.   We have the philosophies and the genetics you will need to prosper in the 21st Century.   If you would like to receive a catalog for our two Fall Bull Sales, call us at 800-311-0995 or send your request to   Our fall bull sales will feature over 350 grass-developed PCC Solar Bulls that will be evaluated and scored for hair coat and fly resistance.  

One response to “Fly Control

  1. Selecting for traits such as internal and external parasite resistance is brilliant. In an era where we are all essentially programed to believe that toxic chemicals are a necessity, and that our livestock will pretty much all keel over and die without pour-ons, multiple vaccoines, and supplemental feed, the Pharo approach to management and genetic selection is a breath of fresh air. After just a little thought, it is obvious that this is the only approach that really makes sense!

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