A field inspection last week showed countless numbers of the week-old insects hopping knee high in fields on the outskirts of Narrabri, a cotton-growing region, 250 miles northwest of Sydney.

Officials said the locusts could threaten hundreds of millions of dollars worth of crops in the Narrabri district alone.

Australia's locust fighters are stepping up efforts to kill the locusts before they start to fly and descend on fields of wheat, barley and canola in the next few weeks.

Rex Simpson, who farms a 8,200 acre spread outside Narrabri, squinted from beneath a weatherbeaten bush hat across infested plains, as baby locusts covered the legs of his blue jeans.

"I've been here for 24 years and this is the third lot that I've seen come through," he said. "And this is by far the biggest lot that I've seen in that time."

Eggleston says six helicopter companies and six fixed-wing aircraft companies are on contract to attack the insects with aerial spray if ground control does not kill them first.

CONCERN OVER MICE

The tiny locusts, now about the size of a grain of wheat, will grow 10 times bigger in the next five weeks, after eating five times their body weight a day.

A dense 250 acre swarm of 40 million insects can eat 10 tons of grains a day - and travel 300 miles a night if weather conditions are right.

Department of Primary Industries information released during Friday's site inspection showed reported locust hatchings as of Sept. 16 were concentrated on the Coonabarabran-Narrabri district in central New South Wales. But hatchings also extended on a 600 mile front throughout New South Wales.

"They're coming in daily," New South Wales Primary Industries Minister Ian Macdonald said, with 172 hatchings reported so far.

"When it's bad they can just blot out the sun," he said.

The New South Wales government, backed by farmer levies, has spent A$2.5 million ($1.8 million) on enough insecticide to cover almost 124,000 acres. It has about A$1 million in reserve. Spending would rise dramatically if widespread outbreaks occurred, Macdonald said.

This is in addition to spending by the federal body, the Australian Plague Locust Commission.

"We have assembled the largest program that's ever been put together in this state to fight this potential outbreak," Macdonald said.

Farmers said there was growing concern over a simultaneous plague of mice. Both outbreaks have been sparked by the breaking earlier this year of Australia's worst drought in a century.

Rural Land Protection Board officials said 2,200 acres of mouse bait was laid around Narrabri on Thursday.

"They come with their dinner jackets on," New South Wales Commissioner Eggleston said of the mice, which particularly like yellow fields of canola now growing in the Narrabri district.