Fly worry for local livestock

The warm wet weather is providing one of the best growing seasons for several years, but with it brings a range of livestock health issues to watch out for due to biting insects.

For cattle this means Buffalo fly worry. Buffalo fly have just made their way to the Mid Coast area in late January, and we can expect their numbers to start building said District Vet with Hunter Local Land Services Dr Lyndell Stone.

“Buffalo fly is both a production loss and welfare issue for your cattle so please monitor numbers on your stock and when they reach worrying levels (often around 200 per beast) it is time to implement control measures to limit production loss impacts,” said Dr Stone.

“Please don’t treat too early as it’s a balance between treating cattle and extending the life of the chemicals.

“Cattle can tolerate a small number of flies, and be guided by how your cattle are behaving – dairy cattle for example may require earlier treatment intervention when levels reach 30 fly per beast.”

The buffalo fly, Haematobia irritans exigua, is a small biting fly, about 4mm long in size. They bite and feed off cattle about 40 times each day causing intense irritation that can result in significant weight loss, a decline in milk production and hide damage from constant rubbing.

They can be spotted on the backs, head and sides of cattle. Annoyed cattle can be seen trying to dislodge them and the constant irritation of painful fly bites disrupts grazing time resulting in the weight loss and decline in milk production. Many infested cattle also develop hair loss and sores around their eyes as well as on the face, neck and shoulders a tell-tale sign of buffalo fly.

Bulls and dark-coated, especially black cattle, appear to be the most prone to severe infestation. Some cattle are more susceptible and allergic to bites and can be intensely irritated by just a few fly.

Both non-chemical and chemical treatment options are available. Non-chemical options include buffalo fly traps and tunnels, Dung beetles and culling allergic cattle. Chemical treatment options can be applied using back liners, back-rubbers as well as ear tags. Producers are reminded to note any withholding periods after treatment and to practice chemical rotation to reduce resistance developing by rotating between Organophosphates (OPs) and Synthetics Pyrethoids (SPS) from year to year.

It is also important to not to automatically reach for pour-on drenches containing Macrocyclic Lactone (ML) solely for buffalo fly control. Using a ML drench solely for Buffalo fly will contribute to drench resistance unnecessarily. Fly prevention options and further information is available on the NSW Department of Primary Industries Primefact Buffalo flies and their control, available from the DPI website.

The flies live permanently on the host animal, with females only leaving to lay eggs in freshly deposited dung and can only live for one or two days away from the host. Newly emerged flies will fly for up to 10 km in search of a host

“Buffalo fly aren’t known to survive over winter in our area, but rather migrate from the north with the right conditions,” said Dr Stone.

“However, truck transport of cattle carrying buffalo fly can spread the fly into new herds and new districts, thus good biosecurity practice is essential so as to not import fly prematurely to an area.

“Once here they only disappear with the onset of colder weather.”

Hunter LLS is interested in mapping the extent of Buffalo Fly in our region this year, please report by calling 1300 705 299, or ask to speak to your District Vet if you have any further questions.

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