Impact and Cost

Buffalo flies are a significant cattle pest in northern cattle, estimated to cost the Australian beef and dairy industries approximately $100m annually. If uncontrolled, infestations may reach several thousand flies per animal, each biting 20-40 times per day. The bites are painful and cause clear irritation to cattle and cause production loss and welfare impacts. The effects of blood loss and interruptions to grazing from irritation caused by the flies can reduce live weight gains by up to 16%. Moderate infestations in dairy cattle (> 30 flies per cow) can reduce milk yields by up to 0.5L per cow per day.

Often the welfare aspects of buffalo fly infestations are a primary concern for producers. Buffalo flies are highly irritating to cattle (see Video 1). In addition, buffalo fly feeding can lead to the development of lesions. These lesions can range from dry, hairless or scab encrusted areas to severe open and suppurating sores. They are found most commonly beneath the eyes of cattle, but also occur on the neck, dewlap, belly and flanks (Figure 1). Development and persistence of the lesions has been associated with a nematode transmitted by buffalo flies (Stephanofilaria). Lesions are most widespread in northern areas of Australia, where buffalo fly are present throughout the year, with up to 95% of cattle affected.

Fly worry in heavy infestations can interfere with mating and may make mustering and cattle handling more difficult. Also the pitted areas at sites of fly bites in tanned skins and buffalo fly lesions contribute to significant discounts in the value of hides from northern cattle. The presence of lesions can also cause price reductions in saleyards and may lead to rejection of cattle for live export. In addition, the lesions present a potential focus for strikes by screw-worm flies which are endemic in a number of Australia’s nearest northern neighbouring countries and which are considered a major biosecurity risk for northern Australia.