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Virginia Cooperative Extension - Knowledge for the CommonWealth

Fly Season Has Arrived!!

Dairy Pipeline: April 2005

Sue Puffenbarger
Extension Area Dairy Agent
Franklin County
(540) 483-5161

You've probably read that first sentence and thought, "It's too early yet!", but it's not too early to start preventative measures. As you probably know, the warm and humid conditions in Virginia and the amount of organic matter on our dairy farms make it the perfect breeding grounds for flies. Flies are a good vector for the spread of diseases such as pink eye and Staph Aureus mastitis. Heifers are extremely susceptible to these diseases as more often than not, they are not being looked at everyday. By reducing the fly population on your farm, you can prevent blind eyes and the spread of contagious mastitis to your herd. Now is the ideal time to start your entire herd on a pour-on fly control product. These products provide the best solution to the fly problem and in addition they can provide protection against worms and eradicate lice. Fly tags alone are not sufficient for reducing populations as research has shown an increase in resistance to organophosphates and pyrethrum due to the slow, constant release of these compounds. Additionally, fly tags do nothing to control flies biting udders. Pour-on control needs to be applied to all animals, including wet calves, beginning now. It should continue every 4 to 6 weeks to be effective. Also, you should rotate products at least yearly, if not twice a year. Rotate active ingredients, NOT name brands. Different name brands can have the same active ingredients. In addition to pour-on fly control, you should consider some other management practices. First, make sure you maintain your facility and minimize areas where manure and other organic material can build up. These are the breeding grounds for flies. Second, consider feeding an oral larvacide to the whole herd, which will control juvenile fly populations and reduce overall loading. All the pour-on and spray will not be effective if you have another generation of flies hatching daily. Lastly, keep good records. Record what product was used and when it was used. Keep track of mastitis, pink eye and other health records to enable your herd veterinarian or Extension Agent to help pinpoint problem areas. By starting now, you too can help reduce (notice I didn't say eradicate!) the fly population on the farm!

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