When do I tag?
A survey was conducted in northeastern Alberta during the pasture season to estimate the infestation level of horn flies. These cattle producers are facing problems with horn fly resistance to insecticide-impregnated tags.
Fly counts were taken from herds using pyrethroid tags and herds using no control methods. This survey resulted in the following recommendations:
- Tag as close to the start of the fly season as possible. Most producers put their tags in too early (April and May). This is convenient, but is a waste of product and time. It is important to remember that the killing period for these tags is 60 days, with most of the insecticide released in the first 30 days.
- Tag cows, not calves. Put tags on animals that carry the highest number of flies. Some producers tag calves at birth or early April but this is not recommended.
- Consider using a self-treatment station (oiler, dust bag, backrubber). Treatment is economical and more importantly, will be continuous throughout the summer.
- Remove all ear tags at the end of each season (September or October). Horn flies exposed to a sublethal dose of insecticide may develop resistance.
- Alternate insecticide used in the ear tags (pyrethroids one year, organophosphates the next).
- Alberta Agriculture
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