Researcher/producers: Horn fly most economic pest for U.S. cattlemen

By MANDY SPIKES | Central Texas Edition

Foil presents research trials to improve horn fly control. -- Photo by Mandy Spikes

May 5, 2003 -- The growing problem of insecticide-resistant horn flies, as well as methods to control the problem, were two of the topics covered during the Merial presentation of horn fly control. This took place at the Texas A&M Beef Center, located in College Station, on May 13.

Dr. Lane Foil, professor of entomology at Louisiana State University, discussed the various research trials to improve horn fly control, particularly in cases where insecticide-resistant flies are documented or very likely to be present.

Dr. James Haw-kins of Merial Veterinary Professional Services talked about the Merial Resistance ID (RID) testing kit and how it helps a farmer de-termine if they have resistant horn flies on their operation.

"My current re-search is on horn fly control and resistance management," Foil said. "We wanted to see the cost-effectiveness of the herd health programs in Louisiana."

He stated that producers think that these parasites are a major problem. "The horn fly is the most economic pest in the United States for cattle. These are not some small studies we are talking about.

"When looking at weight gain studies, we used a team approach. When we evaluated the weaning weight of calves, we saw that most studies show an average of the calves being 14 pounds heavier with fly control."

Foil said that the studies on yearling beef cattle concentrated on both horn fly control and weight gains.

"In a 13- to 16-week trial period of treated cattle, we noticed they had 17 percent higher weight gain. If you can control horn flies in cattle, you can gain approximately a $1.95 investment."

He explained that the first thing to find out is how good a control product is when you want to control horn flies.

"When dealing with horn fly control, it depends on how you are using the product. If you are treating all of your cattle, then control should last six to eight weeks. When you are doing partial herd treatment, it's three to four weeks. When it's the neighboring herds with no treatment, it's four to six weeks. In resistance studies, the number of weeks in control studies is what it's all about."

Foil gave different types of treatment strategies. They are:

• Mixtures
• Sequential use
• Rotations
• Mosaics

"Sequential use is if you use the same chemistry year after year in a consistent pattern. Mosaics are a treatment of separate herds with a variation of insecticides. The mosaics treatment strategy appears hopeful."

The best time to treat for horn flies, according to Foil, is the spring and mid-summer.

"There is some potential for mid-summer if you use the right treatment," he concluded.

"Horn flies are an important pest of cattle," began Hawkins. "We currently have a program, called the RID program, which can help with your situation."

He explained that the program tests horn flies on a farm and determines if insecticide resistance is present. A treatment is then recommended based on the results provided for better horn fly control.

"The benefits of the RID program to producers include better horn fly control and resistance management, better weight gains, and less mastitis in beef and dairy cattle."