UNL discusses treatments for cattle lice during fall

Lice is a common problem for cattle during winter months, and if not treated properly, could led to heavy infestation, weight loss and leave cattle susceptible to disease. 

Producers often check for parasites during fall weaning, pregnancy checking or when cattle arrive at the feedlot. However, early treatment in the fall may only work on some parasites, while others can elude producers and rebound in numbers as temperatures drop.

During an episode of the University of Nebraska-Lincoln’s BeefWatch podcast, dated Oct. 3, UNL Extension Educator Dave Boxler discusses a corresponding article titled “Fall Cattle Lice Treatments,” published in the October UNL BeefWatch Newsletter.

According to Boxler, adding a winter lice control routine using insecticides is an effective approach for treating cattle lice.

Timing

If treatments are applied too early during a long, warm fall, lice will develop slowly and can escape the endectocide treatment.

“Cattle lice are cold-weather insects and thrive during wintery conditions. During summer months, cattle lice undergo a period of dormancy called estivation, when reproduction is reduced significantly,” Boxler states. “Temperatures above 78 degrees Fahrenheit in September, October and November will suppress louse development because cattle skin temperature will exceed 100 degrees Fahrenheit.” 

A lice outbreak can occur when the weather turns cold if the endectocide has broken down. 

Boxler notes, “Livestock producers who use a fall treatment strategy should monitor their cattle for signs of lice, especially during December, January and February and consider retreating.” 

Treatment options

According to Boxler, “Cattle lice treatment products fall into several categories – animal sprays, non-systemic contact pour-on and endectocides like systemic pour-on, absorbed internally, and systemic injectable.”

Using a non-systemic pour-on requires one application, but some products may require multiple applications spaced apart.

Systemic injectables work better on sucking lice, and a systemic pour-on will effectively kill both chewing and sucking lice.

“Using systemic control products between November and February is not advised as they may cause a host-parasite reaction from killing developing cattle grubs while they are in the esophagus or spinal canal of the animal,” Boxler says. “A systemic product used during fall weaning will not be a problem, and if a systemic product was used in the fall, a follow-up from November to February shouldn’t cause those issues.”

However, he notes, “Producers who did not use a systemic control product during fall weaning should consider using only non-systemic control products from November to February.”

Insecticide treatments should be rotated to reduce developing resistance, as the continual use of a single product can lead to reduced control. 

“To reduce control failures due to insecticide resistance, do not apply pesticides within the same group number repeatedly, and always follow label directions,” Boxler states.

“Insecticides and endectocides are an investment of time, money and cattle stress, and there are real costs to insect infestations, so putting a few extra minutes into correctly applying these tools can make all the difference between an effective and ineffective insect control program,” he concludes.

Lice are serious wintertime pests for livestock and can generate significant monetary losses for producers.

Melissa Anderson is the editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.