There is international concern that plagues of locusts could cause billions of dollars worth of damage to Australia's agricultural industry in the coming weeks.

Earlier this year swarms of bugs appeared like giant clouds of green mist in western Queensland, and the weather was perfect for high-density egg laying.

Now, with spring heralding warmer weather, scientists say conditions are ripe for millions of these tiny eggs to hatch in parts of Australia's south-east, bringing even bigger swarms of locusts.

The insects, which gnaw though a third of their body weight in food a day, can devastate crops.

The Department of Agriculture and its Locust Commission says farmers have been spraying sites of eggs and are on alert to report hatchings, which are expected later this month.

Victorian Farmers Federation president Andrew Broad says the Vic Government estimates that the pests could cause up to $2 billion damage to the agricultural industry in that state alone.

"That's not just a figure pulled out of the air just for convenience sake. There's a bit of thought and research gone on to come up with that figure," he said.

Mr Broad says there is a lot of angst in rural parts of Victoria, New South Wales and South Australia, where the swarms are predicted.

The Department of Agriculture says worries about the Australian locust plagues have also reached parts of Europe and the UK.

A Department spokeswoman says they have received calls from London's Financial Times and other overseas news outlets where there are concerns the plague could affect exports of wheat.

Earlier this year ABARE said Australian wheat regions had seen some of the best weather conditions in years, but stressed that locusts posed a threat to what could be a bumper season.

Mr Broad says Australian wheat makes up 20 per cent of the commodity's global export market.

He says floods in Canada and drought in Russia and parts of the Ukraine have severely depleted world stocks, and this year the global market is relying more than ever on Australia's export wheat.

"Vladimir Putin's made an announcement the other day that he's put a ban on all Russian exports of wheat until after Christmas and that's why there's been a huge jump in the price of wheat.

"Western Australia is reasonably dry - which is where a lot of our export wheat comes from - so that really leaves the east coast.

"So you can understand why there's a global nervousness about what could happen in Australia, because of the tightness of supply that's a global issue.

"It does come into play and I suppose there would be - there is a level of interest really through trading houses as to what impact this might be."

And Mr Broad says people in Australia's urban areas should not feel so far removed from the threat of locusts.

He says if Victoria's farming sector was to suffer the potential $2 billion loss the shockwaves would reach Australia's cities.

"I think there's such a naivety about what agriculture contributes," he said.

"People are shocked when you tell them the biggest export out of the port of Melbourne is dehydrated milk which is a dairy product.

"One of our greatest earners is the agriculture industry, and yet most people don't even realise it.

"Victoria's got the AWB based in Melbourne, there's a lot of companies that have got their head offices, logistics and marketing of agricultural products based [in the city]."

For now, as the weather warms and crops ripen, all farmers can do is watch and wait for the locusts to hatch.