3 May 2002


By Wendy Owen

North-east correspondent

SUCCESSFUL fly control in dairy units is largely related to hygiene in buildings and around the farm in general, according to ADAS senior dairy consultant Brian Pocknee.

"Very few flies are brought in from pasture at milking, but they are attracted by dust, milk, manure residues and discarded filter socks," he explains.

"Water sprays containing insecticide at the parlour entrance and in the collecting yard are a deterrent, as are fly traps based on ultra-violet light.

"However, the bulbs on these traps must be changed every 12 months, if they are to be effective. The same goes for fly papers. Although they have the advantage of being cheap, they must be replaced frequently."

Dr Pocknee says there is an interaction between the biting and the non-biting variety of flies. "Biting flies disturb livestock but they also leave behind blood droplets, which attract the non-biting species, such as head fly and face fly.

"These non-biting flies cause the most serious problems with disease spread and are difficult to control. They can survive for several days away from cattle and then only visit for a short time. That means they do not easily pick up a dose of insecticide.

"These flies will readily migrate, so they can come from neighbouring farms. Several generations of many of the species can appear in a season, so more flies will always be hatching."

Low-lying fields surrounded by woodland are often associated with head fly and the spread of summer mastitis.

Therefore, grazing of these fields by dry cows and youngstock should be avoided during warm weather from July to September where possible, he recommends.

When considering insecticides, ear-tags have the benefit of being easy to use and are especially useful for younger animals at grass. Pour-on treatments can work out cheaper, but three or four applications over the summer means extra work, adds Dr Pocknee. Sprays are also helpful in some circumstances.

"With sprays, good handling facilities are essential and it can be difficult to apply the spray evenly. Fortnightly spraying is labour-intensive, but it can serve to direct insecticide to specific parts of the animal – udders for example – during high risk periods," he says. &#42

Low-lying fields surrounded by woodland may increase risks of head fly problems in summer, warns Brian Pocknee.

&#8226 Consider unit hygiene.

&#8226 Trap upkeep vital.

&#8226 Many ways to apply insecticide.

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