They are tiny little creatures but they can have a big impact on your bottom line. Lice are a common problem on cattle. Often, springtime shows up, and soon after the warm weather comes, ranchers notice that their cattle are scratching like crazy. Sometimes large bald patches will appear from the cows and steers rubbing all of the hair off of their bodies in certain areas.
Heavy infestations of lice can reduce the amount of milk a cow gives or the amount of weight a calf gains because the lice are getting the nourishment that the cattle desperately need. Additionally, lice infested animals may spend more time rubbing and scratching than eating because the itching is so severe. The constant rubbing and scratching can destroy fencing, small trees, and other scratching posts.
Lice Life Cycle
Lice are usually passed from a mother cow to her calf. They can also be passed through the herd as cattle congregate or use the same bedding areas. If one cow has lice, there are probably several others who have it too.
Lice can infect cattle all year. However, their numbers are greater in winter because of the heavy winter coats that cattle produce. They may be sloughed off with the winter coat in early summer. Additionally, lice do not do well in warmer weather. They can't tolerate temperatures much higher than 104 degrees Fahrenheit, and the backs of cattle in full sunlight get warmer than that.
Lice have a life cycle that is about 20 to 30 days in length. The female adult insects lay eggs that are glued to the cows' hair shafts. The eggs are called nits. The eggs hatch in one to two weeks and the bugs proceed through a molting process. By the time the lice are 14 days old, they are adult insects, ready to lay more eggs. The bugs bite the cows and sucking kinds of lice will feed on the cows' blood.
Treating Cattle for Lice
The most important thing to remember when treating your cows for lice with pesticides is to re-treat the cows 20 days after the first treatment. Many pesticides nly kill the hatched out insects. Cows will be host to unhatched eggs, and those eggs will hatch in just a few weeks after the original treatment. Treating 20 days later will kill most of the lice on the cows. Do not miss any cows as you treat. A single cow could be a lice reservoir that re-infects all of your cattle with lice.
Many cattlemen use backrubbers or insecticide dust bags with which the cattle can dust themselves. Additionally, some farmers use insecticidal ear tags. While these ear tags are not an excellent method of lice control, they do provide some coverage and retard the lice's population growth.
Another key thing to remember is to keep the cattle well-fed and in good health. Healthy animals are less susceptible to lice infestations.
MU Extension Livestock Specialist Eldon Cole via Flickr