Control of Worms Sustainably (COWS) are warning cattle farmers of the annual emergence of head flies (Hydrotaea irritans) from around mid-July, as these are a major source of annoyance for pastured cattle.
These flies are present until late September, mating and depositing eggs in pasture soil and leaf litter, until colder weather kills them off.
Headflies are nuisance fly and cause considerable irritation as they feed on proteins from secretions such as saliva, tears, sweat and milk, and use this to mature their eggs.
Cattle affected by headflies move to the shade, are restless and may stamp and swish their tails. This leads to less time spent grazing and decreased performance.
Headlfies can be controlled through insecticides, however where insecticides are not used, applying teat sealant to pregnant heifers and dry cows can help stop the spread of summer mastitis bacteria by flies. Garlic licks, fly trapping and the use of fly predators, may offer some form of fly control, but there is little evidence to support this in grazing animals.
View more information on the COWS website here