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Virginia Cooperative Extension -
 Knowledge for the CommonWealth

Beef Management Tips

Livestock Update, May 2002

John Hall, Extension Animal Scientist, Beef, VA Tech

May Beef Management Calendar
Spring Calving Herds

Fall Calving Herds

Face Flies Appear to be Early Problem
The face fly populations appear to be exploding early this year. Face flies are the vector for pinkeye. They carry the Moraxella bovis bacteria from cow to cow which causes pinkeye. In addition, their habit of feeding on eye secretions results in scratches to the cornea allowing the bacteria into the eye. Control of face flies is important in reducing pinkeye. Most fly tags only do a fair job of controlling face flies. Dust bags, dust bullets and oilers are effective methods of controlling face flies. Rotate insecticides yearly to reduce development of resistance by flies.

Wait to Put in Fly Tags
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 horn 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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