How to deal with insects that bother cattle

By Gary Sliworsky
OMAFRA Rep.

This time of year usually results in a bumper crop of flies and mosquitoes and they are as annoying to cattle as they are to humans. Research shows that heavy insect infestations can cause calf growth to be reduced by as much as 15 to 20 percent.
Livestock bothered by flies are extremely uncomfortable and often can be observed bunched together as a form of co-operative protection from the insects. When they are standing bunched together, they are not out eating or drinking like they should be and that means lost production. In addition the insect pests can cause the animals to spend a significant amount of time “running away” which can also result in lower production.
The severity of your fly population and the necessity of introducing a form of control is the producer’s decision. Some options to consider are:
- Ear tags that have been impregnated by insecticide are still a good option. Ideally they should be changed each year to avoid the development of resistant pests. The use of a single insecticide over the long term creates a favorable environment for the few resistant insects that exist in any population.
-Mass treating cattle with sprays can be effective. Cattle need to be gathered together and the spray needs to be reapplied once a week or even more often in some cases.
-Dust bags and rag oilers are self-service insecticide applicators for cattle. Although they are among the oldest fly control methods, they are still effective if they can be placed where cattle are forced to use them regularly.
-Pour-on insecticide formulations provide good protection against selected insects, and the protection can last up to two months.
The method a producer uses will depend on the cost and on how cattle are handled this time of the year.