Sheep areas of southern Australia and Western Australia are facing a major blowfly wave after recent rain and as temperatures increase across parts of SA, NSW and Victoria this week.
Weatherzone senior meteorologist Brett Dutschke said a wave of heat of near-record temperatures would hit inland SA, VIC and NSW this week.
Parts of western and northern SA, north western Victoria and far western NSW, including Kyancutta, Woomera, Mildura and Broken Hill, should reach an average of 35 degrees for the week Sunday October 19 to Saturday 25, he said in a release.
“This is 11 degrees above average and within about a degree of their October records.”
Mr Dutschke said very little or no cooling is likely north and west from Woomera to Broken Hill to Bourke with the temperature reaching the high thirties by the end of the week just ahead of a cooler change.
“With temperatures rising from the mid-thirties early in the week to high thirties late in the week heat-related stress is possible.
“Thankfully most nights will cool down to a comfortable level.”
Calls for early crutching as flies hit in Victoria
Although not much humidity is expected to be associated with the high temperatures and hot northerly winds, humidity levels were at 50-70 per cent in some areas now and contractors are already finding flocks blown by the Australian sheep blowfly Lucilia Cuprina across NSW, Victoria and into SA.
Crutching contractor Jack Briscoe said there will be a massive fly wave, with some of his clients west of Melbourne already reporting up to 20 percent of their second cross lambs getting struck. He has noticed an increase in struck sheep in the past week.
“All my clients are wanting to go early with crutching now.”
Coleraine-based contractor George Pickles said he had been dealing with flyblown sheep in clients’ crossbred and Merino flocks from Elmhurst to the Grampians and over to Coleraine in the past two weeks.
“This northerly wind will bring the flies down.
“Anything that is not maintained is getting struck,” Mr Pickles said.
‘Nightmare’ coming in WA
After recent rainfall of 18-50 mm across WA, Narrogin-based contractor Eddie McEllister was expecting blow flies would be “dynamite” in the next few weeks.
Blow fly problems would be “atrocious”, he said, especially for producers who have not crutched, shorn or jetted their sheep. Some flock owners waiting for shearers would be in dire straits, unable to jet sheep with chemicals with withholding periods that clashed with shearing dates, Mr McEllister said.
“If it comes in warm and sunny here, you will see a nightmare.”
Blow flies on the move in NSW
Canowindra-based contractor Jamie Barclay said he had been using jetting chemicals in his sheep dipping formulation for the past three weeks on his run Nyngan to Carrathool in NSW and down Rutherglen in Victoria.
“The blowflies have started in NSW – there is definitely a fly wave happening.
“If your sheep are not lice-free and they’ve got a bit of skin on them you are going to be in trouble with flies,” he said.
Mr Barclay said flies were experiencing ideal conditions in areas having a good season, with good pasture growth, moisture, and sheep in fat condition.
“I think it is a perfect year for flies.
“The flies are already going ballistic,” he said.
“If they haven’t got their sheep crutched or jetted now, they are going to be in trouble.”
Flies will take off soon in Tasmania
Launceston district contractor Terry O’Toole was marking lambs this week and had not seen any flies.
“We are not finding any in Tasmania yet, but in the next couple of weeks they will be taking off.”
He was jetting lambs in the cradle to protect them from fly attacks and despite some areas of the state being very dry, did not believe this would slow the blow flies down.
Dry, spring-shearing SA not reporting fly issues
However, in the drier conditions of south-east SA, Naracoorte-based contractor Ian McConnell said most of his clients had crutched their sheep and were not reporting fly problems.
“We’ve had not wet weather to hold our crutching up.”
He has seen flies in only one flock and farmers crutching next month for a January-February shearing had already jetted their sheep.
“It’s a very droughty year – it’s not looking like a very good spring.”
Hallett woolgrower and stud breeder Tom Ashby said many producers in the region shore their sheep from the late July to late October, avoiding any blowfly risk.
“I haven’t heard of any big outbreaks.”
Heat wave relief mid-week for coastal areas
Mr Dutschke said on the coast more significant relief from the heat will arrive midweek. A cooler change will move through this Wednesday and another stronger change will arrive next weekend, dropping temperatures by as much as 12 and 15 degrees respectively.
“However, Adelaide may still get within a degree of its October record, a weekly average maximum of 31.7 degrees, set in 1914.
“The city should average a bit over 30 degrees this week, which would make it their hottest October week in 24 years,” he said.
“Melbourne is also on target for its warmest October week in 24 years with a forecast average maximum of 26 degrees this week.”
Mr Dutschke said the early-season heat has been brought about by a reduction in the strength of cold fronts over Western Australia this month, allowing heat to build over the Pilbara and Kimberley with help from sunnier than normal days.
“The heat has been allowed to exceed average levels with the aid of a warmer-than-normal sea surface surrounding western and southern Australia.
“Marble Bar has averaged a maximum of 40 degrees this month so far, two degrees warmer than the October average and we are just entering the hotter part of the month.”
Source: Weatherzone, Livestock Contractors Association.