A recently published MLA report, Priority list of endemic diseases for the red meat industry — 2022 update by Shephard et al. (2022), has revealed that buffalo fly is now the costliest endemic disease to the Australian cattle industry.
Buffalo fly is estimated to cost cattle producers an annual cost of $170.3 million, with $111.7 million attributed to a loss in production and $58.6 million to buffalo fly preventative costs. These findings emphasise the importance of controlling buffalo fly in areas where they are prevalent.
Buffalo flies (Haematobia irritans exigua) are small blood-sucking parasites that feed off cattle, biting their host up to 40 times a day. This causes severe irritation when at high levels and can also spread disease, resulting in pinkeye and lesions around the eyes and body of cattle.
The distress this causes can disrupt grazing time and reduce hide value, resulting in serious welfare and production concerns.
Buffalo flies are prevalent in the northern regions of Australia, closer to coastal regions where conditions are more favourable for their development. Buffalo fly populations build up following an increase in soil temperature and frequent rainfall, typically in spring and summer.
Young adult flies emerge from their pupal stage in the soil and seek out a host on which to live and feed.
“Interestingly, the MLA report indicated that seasonal conditions are driving buffalo fly to expand geographically, says Kim Krilich, brand manager for Elanco Animal Health. “Fly challenge is becoming greater and lasting longer within a season,” she said.
The report acknowledged that controlling buffalo fly is becoming more challenging with increasing resistance developing to available chemical treatments.
“This highlights the importance of recommending strategic use of control measures, to manage buffalo fly effectively and minimise production losses,” Mrs Krilich said.
Insecticidal treatments remain the most effective way to control buffalo flies, but their use should be carefully considered.
Mrs Krilich said short-acting insecticides are ideal for use when buffalo fly pressure is low or at the start of the fly season to reduce their build up and provide short-term welfare benefits to affected cattle.
However, if fly pressure is predicted to remain high for a prolonged time, or cattle are showing signs of fly worry, long-acting chemical control methods such as insecticidal ear tags are more suitable.
Ear tags are recommended in beef cattle when there are more than 200 flies per head or in dairy cattle when there are more than 30 flies per head; this is the threshold at which production is typically impacted and cattle welfare is compromised.
Insecticide impregnated ear tags work by slowly releasing insecticide in a gradual and consistent dose across the body of the animal. Cattle rubbing against each other can also facilitate the spread of the insecticide. Insecticide ear tags are a practical, convenient, and effective way to chemically control buffalo flies in cattle.
“It’s recommended that chemical actives are rotated within a season and from season-to-season. This is an important consideration when planning the insecticidal treatments available to your clients,” Mrs Krilich said.
The active used in a short acting treatment applied at the start of the season should be different to that used in the ear tag.
“For instance, if a macrocyclic lactone (ML) drench has been used at the start of the buffalo fly season to control both internal parasites and buffalo flies, a synthetic pyrethroid (SP) ear tag such as Cylence Ultra or organophosphate (OP) ear tag such as Patriot or Co-Ral Plus should be used during the peak fly season,” Mrs Krilich said.
“The following year, the ear tag active should be rotated.”
Mrs Krilich said the correct use of fly tags as per the label directions is important in ensuring their efficacy and achieving best results. Applying too few ear tags or leaving them in beyond the published efficacy period can help to accelerate resistance development too.
