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 Knowledge for the CommonWealth

Wait to Put in Fly Tags

Livestock Update, May 2001

John Hall, Extension Animal Scientist, Beef, VA Tech

Since most of us work cattle sometime in the spring, there is a tendency to want to put fly tags in at that time. However, this is too early for most fly tags. Fly tags that are put in too early fail to put our enough insecticide late in the fly season. Exposure to low levels of insecticide aids in the development of resistant flies. Entomologists suggest that fly tags are most effective when the flies exceed a threshold level of 100 flies per side. Most of us are not going to count flies and the time when threshold occurs varies from year to year depending on the weather conditions. For most parts of Virginia, producers should delay putting fly tags in cows until early to mid June. More information on specific fly control methods can be found at your local extension office or in the on-line version of the Virginia Pest Control Guide at: Look under the field crops section for livestock.

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