by: Clifford Mitchell

Identifying timelines or setting deadlines often lends itself to successful management. Obviously, things like calving season and breeding season are a given and some of the most important for the operation. Planning often revolves around weather and end product marketing.

Some operators lose site of other timely management practices once the big items are removed from the list. Annual management consists of doing everything possible to bring home the most pounds for any given market period. Fly control will help some producers add pounds at certain stages and could, depending on market price, help increase dollars generated during that time frame.

“Horn flies are an economic pest. Proper fly control will bring economic benefits with growing cattle,” says Dr. Lane Foil, Louisiana State University.

“There is a pest factor involved with horn flies. Without proper control it could cost producers money with decreased weaning weight or losses in average daily gain (ADG) with yearling cattle,” says Ken Kelly, Beef Cattle Extension Specialist, Auburn University.

Certain areas differ in horn fly populations and the need for extra management. Identifying when horn fly populations become costly, is key to effective control.

“In South Alabama, and many areas along the Gulf Coast, we have year round horn fly populations,” Kelley says. “Usually, May through October, depending on the weather, are months we see horn flies become a problem.”

“Growing cattle are really susceptible to this economic pest. We have year long horn fly populations and we have to identify when it's time to take action,” Foil says. “The economic threshold for fly control is 200 horn flies per cow, which is 100 per side. Depending on the year once horn fly populations reach 50 per side that is what I call the “action threshold.” Once we start seeing this population of horn flies it will reach economic threshold (100 per side) in about two weeks.”

Proper fly control, like most management tools, begins with correct timing. Identifying the proper threshold can help producers achieve desired weaning weights or ADG on grazing cattle.

“If you're going to sell those yearlings early on before horn fly populations rise there is no need for fly control,” Foil says. “Spring calving pairs can see a big increase in horn fly populations and there is a good chance they will need some form of fly control. If we can offer some fly protection for the dams of those calves you should see an increase in milk production.”

“If we can control horn flies at the proper time, there will be some increase in weaning weight and ADG on grazing cattle,” Kelley says. “Sometimes these increases can be pretty significant, which should lead to more dollars at the market place.”

Working with the current management system may help get fly control off on the right foot. Sometimes other management practices will dictate when cattle need to be gathered and method of fly control.

“A lot of guys in my area will use a pour-on de-wormer in the spring and fall, this offers up to six weeks of fly control. A lot of producers will take advantage of this early control,” Kelley says. “Most operators will de-worm early then put in a fly tag sometime in May. Temperature, humidity and other factors that could increase horn fly populations, will dictate control methods in our area.”

“In Louisiana, a mid summer de-worming works really well because some internal parasites are very susceptible to treatment at this time. A lot of these pour-on products offer a six to seven week period for fly control,” Foil says. “If producers want to take advantage of this then cut out the fly tags and use this form of control.”

For many reasons, fly tags have become the “method of choice” for most cattlemen to protect their livestock from the pests. When horn flies reach the “action threshold” it is a good time to apply this form of control. Rotating the fly tags with different chemistry is important.

“Mutual contact and cattle grooming each other will spread the insecticide and among the animals to offer control,” Foil says. “Horn flies will produce 15 generations per year. Resistance will develop in a two to three year period.”

“Fly tags are really handy for us long term,” Kelley says. “They are slow release and, if you follow rotations, will provide control for a long term basis.”

There are several different chemistries or tags with active insecticides available. Most producers have defined a rotation that works. Resistance to those chemicals is often when discrepancies in fly control will start to occur.

“Most of the time producers can get by with a rotation that consists of two years organoshosphate (OP) and one year pyretheroid tags,” Kelley says. Resistance can build quickly with some products. Where producers run into trouble is using the same chemistry year after year.”

“Using OP tags for two years and something different in the third year could be a logical rotation strategy for most producers,” Foil says. “OP tags can be used year after year and a low level of resistance will start to build. I wouldn't recommend using a pyretheroid for more than two years in fly control rotations.”

Obviously, each operation takes a different approach to when and what class of livestock get tagged for fly control. Several different schools of thought come into play; however, tags cost money and some producers may be over doing it when it comes to fly control.

“Basically, I don't see any reason to treat calves while they're still on the cow. Calves are relatively exempt from horn flies when they're on the cow,” Foil says. “The closer we get to weaning, calves are out grazing and may carry a few more horn flies, but they don't really carry threshold numbers until they are weaned.”

Many factors can lead to resistance building with the fly populations. Removing tags at the end of the control period will help producers use effective chemistry when horn fly populations reach threshold levels the next year.

“The important thing for producers to remember is if something's not working get those tags out and change chemistry in the tag. If fly thresholds are reaching 50 per side the tags aren't working that well. Remove those tags before the economic threshold, this will help stop the resistance mechanisms in the horn fly,” Foil says. “Taking tags out after fly control season is really important. If you leave tags in for long periods of time you are only penalizing yourself. Resistance will be created through mismanagement.”

“There is not a certain date when we have to remove those fly tags in the early fall and take advantage of a pour-on de-wormer for extended fly control,” Kelley says. “Let those cows go through the winter without fly tags. This will help decrease resistance in horn fly populations.”

New forms of fly control are always on the radar for certain producers. Some new products or management practices that could help support the “Green” movement are always an avenue for some operations. Effective control may not be tied to chemicals.

“Feed-through products have gotten better over the years. If you are going to take advantage of feed-through products make sure your neighbors are doing the same. These products won't affect what is on the other side of the fence and you'll still have a problem. Producers employing this control will be disappointed if their neighbors aren't using it,” Kelley says. “Rotational grazing will work to some degree for fly control. If you are rotating in short periods it probably won't help, but long rotations could be successful. If you can take away the host for at least three weeks, the flies will move on and you should see some benefit.”

Today's environment of decreased profit margins has most producers concerned about cost. Cost for effective fly management will vary from operation to operation, but producers should be concerned about the advantages they receive.

“Everybody is different when it comes to per head costs for fly control. Producers have to take in many factors such as labor and the time it takes to work cattle through the chute. Tags will cost roughly four to five dollars per head and then each operation needs to figure variable costs,” Kelley says. “There will be an increase in weaning weight and ADG for grazing cattle, which should far outweigh the cost of effective horn fly control.”

Successful fly control will come in many different forms. Sound management must be in place for operations to receive the benefits of eliminating horn fly populations.

Good nutrition, genetics and herd health will be complimented by adding another step to the overall management philosophy. Common sense will go a long way to help execute profitable fly control.

“There is no “one best fit” to fly control. Each operation has to adapt it the management program and do what works best for them,” Foil says. “The ear tag is a very good tool for effective control. Each operator will find what works best for them. The main thing is to use some common sense and if something isn't working don't use it the next year.”

“If you have good grass and well managed cattle, in general, effective fly control should provide some benefit,” Kelley says. “If it means adding an extra $30 or $40, any way you can, to the current system, controlling horn fly populations should help increase dollars per head returned to the operation.”


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