MINIMIZING THE RISK OF RESISTANCE AND MAXIMIZING GAIN

How they work

First introduced in the early 1980s, insecticide ear tags containing organophosphate or synthetic pyrethroid insecticides, provide relief and suppression of both horn and face flies. Horn flies are known to cause considerable stress in livestock. Visible on the backs of cattle, these aggressive pests bite through the hide 20 to 40 times daily, drawing blood and reducing weaning weights by as much as 14 per cent.

Face flies, also very bothersome to cattle, feed on animal secretions such as eye discharge and interrupt gain. These flies are noted to be responsible for a one-hour reduction in grazing per day during fly season. Additionally, face flies can also spread the devastation of painful diseases like pink eye in cattle, which is known to impose reductions in weaning weights from 17 pounds up to 65 pounds per animal.

The life cycle of both types of flies discussed involves eggs being laid in cattle manure. Their entire life cycle lasts two to three weeks, which means there can be up to five life cycles through the summer in our Alberta climate. The ear tags work by breaking the fly cycle and killing adults early – helping to reduce the fly level for the entire season.

"One of the common questions that I get – not just from producers, but from veterinarians as well," says MacNeil is; "How can ear tags be so effective against face and horn flies in cattle? With less than 10 grams of insecticide in the product, they want to know how this little tiny tag on ears can offer this level of protection and relief."  

MacNeil says that there are two factors that support the effectiveness of the insecticide ear tags.

"The first reason is that because cattle comingle, they are constantly rubbing up against each other which supports the spread of insecticide between herd members. The second reason is that the fat or lanolin content of a calf or cow's coat is quite high or what is called 'lyopophilic' which means it loves fat. It is what allows the insecticide to easily travel and migrate through to the grease or fatty layer in the hair. It is quite remarkable that one little tag is able to pass the insecticide ingredient down through the face and the neck, down the back, flank and brisket and head toward the loin – thanks to the oily nature of the cow's coat," says MacNeil.

Avoiding Resistance

"When used correctly, fly tags can be one of the best pest management tools available to cattle producers. However, improper use can be costly when it comes to their ineffectiveness, or even worse, can be counter-productive and lead to a build-up of resistance in the fly populations," says MacNeil.

Failure to read labels, using only one fly tag rather than a tag in each ear, not tagging calves or applying tags too early in the spring, can all lead to ineffectiveness and resistance in the fly populations. When it comes to avoiding resistance and maximizing the performance of ear tag fly control this grazing season, MacNeil recommends the following best practices.

BEST PRACTICES FOR EAR TAG USE:

Read the Labels and Alternate Use

"Resistance can occur when tags containing synthetic pyrethroid, such as permethrin, have been used for several consecutive seasons," says MacNeil. "That is why it is very important to read labels for use, as well as understand the active ingredients, not just the brand of ear tag. Simply switching brands will not always mean that you are alternating insecticide. Keep records of ear tags used and their active ingredient(s) each season to help avoid any confusion over what ear tags to use the following year."

Alternmate Use or Use a Combination Formulation Ear Tag

"One of the advancements we have seen since the introduction of insecticide ear tags in the early 1980s, is the availability of combo tags," says MacNeil. "Canada was first to offer a combo tag to cattle producers. Combo tags like Eliminator® are now available this year at UFA. These tags contain 11 per cent Diazinon (an organophosphate) and six per cent Cypermethrin (a synthetic pyrethroid). You can use them year after year without the concern of resistance. They provide very good activity against susceptible and resistant fleas and suppression of face flies with two tags," says MacNeil.

Be "All Ears"

"When applying the ear tags, be certain to apply tags in both ears, if recommended by label use instructions. There is no merit in only administering half the dose and putting in one fly tag per animal," says MacNeil. "You can cause more harm with half the dose by limiting the effectiveness of the tag and contributing to fly resistance."

Tag Calves

"It is very important that your fly control program includes calves – not just the cows," says MacNeil. "Limitations on age will vary on tags - all the more reason to make a proactive fly control plan and part of that plan means selecting appropriate tags that work for your entire herd. You absolutely want to make sure that the tags are labelled for use on calves and that the label meets the weight requirements. 

Timing - Avoid Being "Too early - too short"

Providing almost 100 per cent protection from flies for the first few weeks, on average, insecticide ear tags will provide 12 to 15 weeks of fly control. However, applying the tags too early will result in a lack of sufficient coverage into early fall. Additionally, low insecticide levels will contribute to the risk of resistance going into late fall.

"The closer you can treat your cattle to the actual fly season the greater the benefit."

"Where we also run into resistance issues can be with timing," says MacNeil. "For producers who turnout early or late April, or even very early May, it can be too early and too short, infringing on a time when fly population is not that high, and subsequently, when the cattle don't need that much protection."

In Alberta, MacNeil recommends applying ear tags mid-May or when an accumulation of horn flies (around 50 per animal) can be seen. 

Remove Ear Tags at the End of the Fly Season

"The single biggest contributor to ineffectiveness is failure to remove fly tags at the end of season as recommended," says MacNeil. "It is important to cut those tags out at the end of the season, so that they are not releasing very low levels of insecticide which are going to encourage mutations and subsequent resistance in fly populations.

"It is also important to ensure the proper disposal of used tags. Like any end-of-life pesticide, most municipalities or communities have pesticide disposal sites and that is where fly tags should ultimately go," says MacNeil, who also reminds producers to always wear protective gloves when handling insecticide treated tags.

UFA supports the cattle industry by delivering the tools, products, services, and support for optimal herd performance. To learn more about our products, please visit your local UFA Farm & Ranch Supply store or connect with us by calling 1-877-258-4500, Option 1.