Locusts have begun swarming in Victoria for the first time in three years.
Authorities battling locusts in Victoria's north observed a flying locust swarm on Tuesday, a strong indication that this season's locusts are hungry and getting ready to move and breed.
The swarm was noticed in a farming area south of the township of Dookie, near Shepparton.
And an unconfirmed report of a swarm was made north of Dookie at Katamatite.
Rainfall in the state's north last week has helped the locusts, by promoting growth of crops and of grasses on roadsides and in paddocks.
All are feed sources for the insect.
Sightings of swarming locusts are worrying news for Victorian agriculture, because it is an indicator of the size of this year's locust outbreak.
Locust swarms have not been seen in Victoria for three years and in recent decades have only been seen in the state about once every 10 years.
The Victorian Department of Primary Industries considers locusts "formidable eating machines that can rapidly devastate crops".
The threat locusts pose to agriculture comes from their appetite and their mobility.
They can travel up to 700 kilometres in one night and up to 20 or 30 kilometres during the day.
Entomologists from the DPI have already confirmed more than 400 samples of locusts found in Victoria as the Australian Plague Locust, the most damaging type of locust to Australian agriculture.
Victorian Agriculture Minister Joe Helper said that while drier conditions in some areas had killed some locusts, large concentrations of young locusts are still alive in some areas where feed is available.
"We expect to see locusts swarming in the next week or so and members of the community especially those in northern Victoria, who have not previously seen locusts, need to be prepared for their arrival," Mr Helper said.
"The DPI has already used over 12,500 man hours conducting strategic surveillance for locusts covering an area of 1.5 million hectares," he said.
The Victorian DPI's plague locust commissioner, Andrew Tomkins, said a lot of the locust sites in Victoria did not have a high density of locusts.
"That doesn't mean to say that they won't fly.
"They'll fly, but they probably won't be swarming in the fullest sense of the word," he said.
Dr Tomkins said the forthcoming hotter days would see more locusts become mature enough to fly, while the warmer evenings would make them more inclined to fly.
The director of the Australian Plague Locust Commission, Chris Adriaansen, said the most significant locust populations are in Wagga Wagga, Narrandera, Junee and Temora.
"In terms of Victoria, the greatest potential for a locust problem over the coming weeks will be migration of locusts from areas of New South Wales," he said.
* Locust sightings should be reported to the Locust Reporting Line on 1300 135 559.
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