Once and Done With Fly Tags
By Caitlin Richards
Insecticide cattle ear tags, also known as fly tags, have been around for decades. Over the years, the science behind them has improved their performance, making them a more practical and efficient pest control tool for producers.
“They fit the management system of most producers very well,” said Larry Hawkins, senior technical service veterinarian with Bayer Animal Health.
Most fly tag products are effective for up to 5 months (150 days) and protect cattle not only from flies but from ticks as well. The primary species fly tags protect cattle from are horn flies and face flies. Producers should confirm the specific species of pests and the effective range listed on the fly tag’s label before use.
“Fly tags, for the most part, are effective against face flies and horn flies because they are the only species of flies on the animal,” Hawkins said. “Stable flies are only on the animal intermittently and they bite the legs. So, the fly tags are not effective against stable flies.”
Once on the cattle, fly tags work in a similar manner as insecticide sprays. The 2 differ in the way the insecticide is applied. Hawkins explained that the way fly tags work is through the insecticide rubbing off the surface of the tag and onto the cattle, rather than being sprayed.
“They work by rubbing insecticide off as the cow interacts with her calf, herself through grooming, and her peers in the pasture,” Hawkins said. “So, if we have 100 cows in the pasture, as they mingle and rub against each other they rub insecticide off themselves onto the other animals and vice versa.”
Some people, Hawkins shared, think the fly tags emit a vapor cloud of insecticide that surrounds the animal. However, this is incorrect. Fly tags are made by mixing the insecticide with a soft plastic to allow the insecticide to easily pass from the fly tag to the cattle.
The way the insecticide moves through the plastic to the tag’s surface over the 150 days is merely a basic chemistry principle — chemical equilibrium. Any chemical, Hawkins explained, aims to achieve equilibrium.
“In the air, you naturally have no insecticide, but in the tag, you have more insecticide,” Hawkins said. “It tries to move to the environment with less in it to achieve equilibrium. So, its tendency is to move to the surface of the tag. Then that gets rubbed off and more moves to the surface and the cycle repeats itself.”
Producers should keep in mind that the environment of the cattle can impact this chemical process, thus resulting in a varying effective range. Temperatures, rainfall and how frequently the cattle wade into the pond can all impact the fly tags, Hawkins said. The best way for producers to ensure fly tags are still effective is through monitoring the number of flies around their cattle.
How many tags and where to attach them
For optimum control, some fly tag labels may recommend attaching 1 tag per ear (2 per animal). Hawkins explained that this doesn’t double the fly control but allows for more fly control. With the presence of 1 tag in each ear, the cattle are more likely to rub the insecticide off. Hawkins also shared that the tags are more effective when attached to the front of the ear rather than the back.
“The key feature is to have some portion of the tag exposed where it hangs below the perimeter of the ear,” Hawkins said. “In my opinion, if it is placed high in the ear, with none below the perimeter, it is detrimental to the application of the insecticide.”
Fly tags are attached to the ear of cattle the same way as an identification ear tag. Because of this, the fly tags work well with a producer’s management system. Typically, producers will apply the fly tags when they are already working or moving their cattle for other management reasons.
For most producers, this occurs in March, which is before the fly season starts in most of the continental U.S., Hawkins said. The tags would then be effective until August, which is the peak of fly season. At that point, the fly tags would need to be supported with another form of pest control, such as an insecticide pour-on or spray.
“When they get to the peak of the season, the amount of insecticide coming out of the tag, as far as depletion goes, is getting to the end, so less is coming out,” Hawkins said. “It is better to wait until you have flies on the cattle, but I tell producers to do what fits their management season best.”
One hand, 100 flies
The real advantages of the fly tag can be seen when producers wait until there are 50 to 100 flies on the cattle to put in the ear tags. Then producers only have to apply the tags once and the effective range will carry them through the peak of fly season. Producers should do what is best for their operation, though. Regardless of the application time, the fly tag is a practical and efficient pest control tool that also protects a producer’s bottom line.
Flies negatively impact the cattle’s performance by hindering their ability to graze, because the cattle try to protect themselves naturally by bunching together, taking shade or standing in water. According to Bayer Animal Health, if an animal has less than 200 flies on their body, their performance is not inhibited. However, if the animal has more than 200 flies the cattle’s performance decreases.
To help producers calculate the number of flies, Bayer Animal Health estimates that 100 flies can fit in the area covered by an average-size hand — fingers, thumb and palm included. Hawkins said it basically gets down to how many pinpricks from the horn flies the cattle can take until it messes with their normal activity.
“Horn flies feed between 20 and 40 times a day,” Hawkins said. “So, if you have 200 horn flies on an animal and you use an average of 30 bites per fly, then it is getting 6,000 bites a day. That’s a lot of pinpricks and the more of them the animal has, the more they tend to seek areas to protect themselves instead of grazing.”
The economic benefit of controlling flies, Hawkins said, is around 12 pounds. Controlling flies on a nursing cow could result in an increase of 12 to 15 pounds in a calf’s weaning weight. The same economic benefit of 12 to 15 pounds holds true for stocker cattle as well, Hawkins said.
A producer’s schedule is busy and constantly full of to-do lists. Fly tags can help alleviate the repeat to-do item of fly control though. A 1-time application with the fly tags versus multiple applications with pour-on and spray products, which may have to be done every 3 weeks, can save producers time and money in the long run.
“Although the fly tags may have to be supported a little at the peak of fly season, they don’t require continual maintenance throughout the summer,” Hawkins said. “They fit a producer’s management system and don’t get in the way of hay baling, soybean planting, wheat harvest and the other things most producers are also trying to do in the spring.”
“Once and Done” is excerpted from the March 2018 issue of The Cattleman magazine.