The heatwave has led to a big increase in nuisance fly numbers.

Most farmers have got bitten by horseflies at least once over the last few days.

They’re a big problem for cows and cattle and can lead to animals bunching together away from trees and hedgerows to try to escape the flies.

They also make cows agitated in the milking parlour and generally more difficult to handle.

For this reason, treating cows and cattle for flies is a good idea.


Most products are relatively low cost and have zero milk withdrawal.

Treated animals are no longer bothered by the flies.

It’s particularly important to treat in-calf heifers or dry pregnant cows on a regular basis to prevent summer mastitis.

Some farmers say that lost quarters in first-calving heifers originate from a summer mastitis infection.

Topical treatments such as Stockholm tar can be used to keep flies away from udders in heifers and dry cows.