When used correctly, insecticide-impregnated ear tags can be one of the best pest-management tools at cattle producers' disposal. But beef producers shouldn't be cavalier about their use and application, says Larry Olson, Clemson University Extension beef specialist, Blackville, SC. He says producers often find the ear tags work great for the first year or two, with results falling off in the third year.

"Problem is, fly tags are often not used according to label instructions," Olson explains. "Their improper use resulted in a build up of resistance in the fly populations to the insecticide in the tags." He says insecticide ear tags can be a very effective and safe means of pest control, but it takes some attention to detail.

Some reasons for resistance include: Using only one tag/animal when two are recommended.

Not tagging calves.

Applying tags too early in the spring. However, Olson says the single-biggest contributor to fly tag ineffectiveness is not removing them at the end of the fly season as recommended. He says producers also can find themselves in trouble if they don't have a plan for alternating ear tags.

"Keep records of which tags you use to avoid any confusion over which ear tags to use next year," Olson says. "It seems like a simple thing, but we see a lot of wrecks with fly tags because producers couldn't remember."

Some things to keep in mind when using insecticide ear tags: Check labels carefully for any use limitations, such as lactating dairy cattle and animal age.

If resistance is a potential problem, check the labels carefully to avoid using the same active ingredient.

For horn fly control, it's best to tag animals after horn fly numbers reach 50 or more/side.

Time tag application to the fly hatch and activity for your region. Tags normally provide 12-15 weeks of fly control.

Remove tags at the end of the fly season to reduce the potential for insecticide resistance in both lice and flies.

Because insecticide concentration in the tags varies from 8-36%, handle them with caution.

"If you don't wear plastic gloves when you use these ear tags, you're asking for trouble," Olson says. "Don't touch your face when handling them, and be careful where you throw away the used-up tags at the end of the year." --- Clint Peck