Although difficult to imagine why, flies do have a role in the master plan of nature. As far as cattle go, however, flies lack any redeeming value. Their control has led to creative chemical and mechanical remedies. Unfortunately, we often ignore the basic consideration needed, that of environmental management.

Since fly propagation relies on moisture and organic matter buildup, wet bedding, manure piles, waste feed or even the neighbor's grass clippings are ideal places to mass produce these pests. Only the horse and deer fly do not take advantage of manure or manure laden material as a choice breeding ground.

Production and health problems
Flies in our climate are not important disease carries. Pinkeye and some mastitis problems can be directly attributed to flies irritating the eye or teat end and introducing pathogens. The biting stable and horn fly are considered the most economically significant ones impacting weight gain in youngstock and milk production in cattle. Horn flies are pasture pests. A 10-20 lbs. missed opportunity weight gain is common for youngstock during the grazing season. For dairy cows, a 20% drop in milk production can be experienced with regular grazing.

Closing down the fly brooder house - things to do

• Clean up waste feed and manure piles within one week's time.
• Don't let rainwater, manure and silage leachate puddle if possible.
• Spread manure as thin as possible to promote dry down.
• Don't let feeding areas in front of calves and cows in the barn or out on pasture build up and stay wet 
• Use shavings, sand or pea gravel in fly season for bedding instead of straw.
• Keep in mind that the base of un-wrapped round bales stored in the field afford the same breeding ground as more obvious problem causing organic waste.

Other fly control measures
Natural control of flies does exist in the form of small wasps, mites and beetles. The extensive breeding areas our livestock production areas provide is large, however. Fly reproduction is much more rapid than that of their enemies. The release of fly predators (often small wasp-like insects) on a regular basis starting in mid-May effectively keeps the fly population explosion from happening. This does not work very well if a close neighbor does nothing as far as fly control and exports their flying friends to your place or you start predator release in July!

Premises sprays can be useful particularly around calf hutches and breeding ground sites. Keep in mind, however, that some of these pesticides will not only kill flies, but the natural or store bought predators to boot! Check the label. Products that kill fly larvae in manure can be fed to both the old and young. Clarifly® and Rabon® are examples. Neither of these poses a threat to natural fly predators if used this way. Both products kill the fly larvae preventing any pupae from developing. It is the pupal stage, not the earlier larval one that fly predators attack.

Fly tags, back rubs, dust bags, insecticide sprays or pour-ons are useful tools against flies, but precautions about labeled use in dairy cattle must be taken. Effect and duration may vary widely. Sprays should never be mixed with diesel fuel or other oils before application. Toxic levels of absorbed insecticide may result. Keep in mind that products must be rotated and used according to label to avoid fly resistance problems.

Don't forget the old-fashioned sticky tapes and ribbons. These can control low to moderate fly populations around premises if changed when needed. Devices such as the Epps Biting Fly Trap™ can be very useful on species not controlled by predators, larvacides or premises sprays. These attract flies by contour and lighting contrasts mimicking how animals appear to biting flies.

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