The warble is a major economic pest of cattle in Alberta. Warble grubs, which are the larval stage of the "heelfly," spend over nine months in cattle as internal parasites. During this period, they damage the meat and hide of infested animals and are responsible for reduced milk production in lactating cattle and lower weight gains in calves. Both cattlemen and packers incur severe economic losses in the absence of a warble management program. In Alberta, there is a province-wide organized warble control program helping Alberta cattlemen and the packing industry. According to the Agricultural Pest Act, all Alberta producers must take active measures to control warbles in their cattle. To manage warbles at the farm level, it is necessary to understand the biology of the insect and the method of action of the various pest control products.
The warble fly is a declared agricultural pest under the Pest and Nuisance Control Regulation.
- Fact sheet about warble flies, their impact on cattle, systemic insecticides for warble control, and treatment methods.