Technology is now available to help ranchers, cattle feeders, dairy operators and horse enthusiasts control both sucking and biting lice in their animals.

Most pour-ons only kill adult lice and nymphs, but a pour-on insecticide containing both a pyrethroid insecticide and an insect growth regulator (IGR) prevents eggs from hatching in addition to killing adults and nymphs.

This can cut down on time spent trying to control lice in the fall and winter, which could, in turn, save time and money.

“Products that kill eggs in addition to nymphs and adults require

Treating cattle for lice can be uncomfortable for cattle and producers alike because control efforts often happen in October through January, as was the case on this very cold December day in Idaho. (Photo courtesy Doug Ross)
Treating cattle for lice can be uncomfortable for cattle and producers alike because control efforts often happen in October through January, as was the case on this very cold December day in Idaho. (Photo courtesy Doug Ross)

only one treatment for optimal control instead of the typical two treatments,” said Doug Ross, senior technical services entomologist for Bayer Animal Health.

Bayer’s senior technical services veterinarian Larry Hawkins added: “Research is showing that one treatment of this dual-action formula is working very well in controlling both biting and sucking lice. The pyrethroid kills the adults and nymphs, and the IGR stops the eggs from hatching.”

But that doesn’t mean that one treatment will protect your cattle and horses throughout late fall and winter, especially in the colder middle- and northern-tier states, where lice populations are often at their peak.

“It seems like every year I have producers call and say, ‘Larry, my bull sale is in a month and I have a severe lice problem. I already treated for lice, but now they’re infesting the bulls that I will be selling. What’s going on?’”

Hawkins said that if you treat for lice early in the fall, whether using a two-treatment pour-on or the one-treatment pyrethroid plus IGR, it’s important to carefully monitor animals through fall and winter and implement another treatment if lice populations are coming back.

“Don’t wait for a population outbreak,” Hawkins emphasized.

And for the producer who has an upcoming bull or female sale, try to isolate those animals after treating them.

“If that’s not possible, certainly observe them and treat them as soon as there is an effect from lice so that you don’t end up with severe infestations and animals with hair loss and other problems.”

Hawkins said that one of the biggest reasons he sees for ineffective louse-control programs is when a cattle producer, feeder or dairy operator using a low-volume pour-on only treats the back of the animal to save time and effort.

“Lice tend to get into the groins, into the armpits, under the sides of the neck and onto the heads of animals. And when you only pour 30 cc (a syringe filled to the 30 cubic-centimeter mark) on the middle of the animal’s back, those lice have to move a long way to come into contact with the insecticide,” Hawkins said.

“Instead of just applying the insecticide in one spot, make sure you distribute it from the top of the head to the base of the tail,” he stressed. “Regardless of how it’s done, you need to make an effort to spread out the dosage.”

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