The Australian Plague Locust Commission said swarms that began appearing about two months ago in northeastern Queensland state had now spread to New South Wales in the southeast and that breeding conditions were ideal.

"Over the last week, substantial redistribution of adult locusts has occurred with movements into northern New South Wales ... locusts have started to develop eggs and laying is imminent," the commission said.

More than 200,000 hectares (494,000 acres) have been sprayed in a bid to contain the plague but the rain that ended 18-months of drought has aided the locusts by rendering insecticides sprayed from aircraft virtually useless.

New South Wales farmer Joe Davis, who has already lost crops he hoped would feed his sheep through winter to the locusts, said he had been warned to expect the worst.

"In a few days, we will see locusts that will just black the sun out," he told ABC television. "There won't be a green thing, they'll even eat the clothes off the washing line."

Lisa Thomas, a senior ranger with the Rural Lands Protection Board at the town of Dubbo, said crop losses had been as high as 80 percent and the plague was getting worse.

"Since Friday we've had swarms blow in, prior to that we just had a light scattering," she said.

TERRA.WIRE