Plague locusts a 'ticking time bomb' for Victorian farmers

Locust numbers in Victoria's north-west are at their highest level in 15 years, as concerns grow that recent egg laying could lead to big swarms this spring.

The native insects, naturally found further north in Australia, have migrated into Victoria in recent months.

"It's just been a really good season for locusts with all the rain and the green feed," said Victoria's plague locust commissioner, Kyla Finlay.

"At the moment they are in high numbers as adults, so there's some localised swarms around."

Those adult locusts are laying eggs, which has farmers concerned about what could happen when the weather warms up.

'Ticking time bomb'

Ron Hards is a cropping farmer in the Millewa in the state's far north-west.

He has had a small number of locusts at his place this year, but is more concerned about the insects that have laid eggs to the north of him.

"We know they've laid up on the river country, adjacent to the [Murray River]. There's hard red flats up there and they love that sort of ground," Mr Hards said.

"Who knows how many more between here and Queensland that there are and [have] laid eggs and will hatch later on."

Mr Hards said it was now a waiting game.

"You've always got to be concerned about locusts when you know they've laid somewhere," he said.

"There will be a window where they will hatch after a rain and in the warm weather.

"I think it's a ticking time bomb."

Highest numbers since 2011

Locusts move into Victoria intermittently, but there has not been a big plague in the state since 2010-11.

"That was off the back of a couple of seasons of very good weather," Dr Finlay said.

"We had migrations coming down from New South Wales all the way down to Melbourne actually, and a lot of people will remember that time."

Locusts multiply quickly and migrate over large distances, causing damage to pastures, crops, gardens and sports grounds.

Dr Finlay said locusts could "devastate a crop seemingly overnight" when they were in high numbers.

"The nymphs can band together and march across the landscape and you can often see that from the air," she said.

Mr Hards said he had seen a seen several bad plagues in his time.

"Probably 30 years ago, there was a bad plague and they just decimated crops," he said.

"They were in their millions then.

"So we don't really want to see them like that again. We'll do everything we can to prevent that happening."

Monitoring continues

Despite evidence of egg laying recently, Dr Finlay said it was still too early to predict how bad the locusts would be later in the year.

"Those eggs laid now and over the next couple of weeks will be in the soil all through winter and then they will hatch in the spring," she said.

"We are monitoring and surveilling what's happening on the ground now and that will determine where we go and look."

Locusts can be controlled with insecticide spray, but Dr Finlay said it needed to be done when they were small to be most effective.

"About two weeks after hatching when they're quite small, around 10 millimetres, they're not able to fly, so that is the best time to hit them with the spraying," Dr Finlay said.

She said she was optimistic about controlling the destructive insect.

"We are getting better at monitoring and forecasting and we think that's why we haven't had a plague for so long," she said.

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