Landholders in the Riverina and central NSW are being urged to continue monitoring for plague locusts throughout the warmer months, even if they see mature locusts in the air.

NSW Plague Locust Commissioner Graeme Eggleston said new waves of locusts could continue hatching in affected areas for many weeks and hatching could start in previously unaffected areas.

"Hatchings over the last month have confirmed our fears of widespread egg laying last autumn and there could soon be a new generation of eggs laid as surviving locusts mature," Mr Eggleston said.

"It is vitally important that landholders continue looking for banding locusts, especially if they noticed any locusts in autumn.

"Banding locusts can be very hard to find, especially in crops and good pastures, so farmers need to get out and have a close look over their whole property regularly.

"There is a good chance you won’t see them until you are literally almost on top of them."

Signs to look for are an unusual patch of discolouration in pasture or crop and increased bird activity near the ground, according to Mr Eggleston.

"At the front of a dense band there is a thick dark mass of locusts that can number into thousands per square metre," he said.

"The length of a large band can stretch for a kilometre or more, devouring all green feed in its path as it moves and the locusts mature.

"Banding is much easier to spot from the air, so we are conducting aerial surveys in some hotspots and areas where locust activity was reported in autumn.

"But landholders should not rely on aerial surveillance to do the job for them."

Mr Eggleston said the worst affected areas continued to be the Wagga, Gundagai, Narrandera, Forbes and Condobolin Rural Lands Protection Boards (RLPB).

"Large number are also reported from Murray, Hume, Young and Riverina, with parts of central NSW now hotting up," he said.

"Hatching started late September and hopefully we are over the biggest wave of hatchings, but we don’t know for sure.

"That is why landholders need to look closely for both banding locusts and fresh egg beds, and report them to their local RLPB.

"In fact landholders are required by law to report locusts and to treat locusts on their property.

"If locust density is high enough on your property and they are a threat to your neighbours, you will be supplied with the appropriate pesticide.

"Assistance will only be given in situations where the scale of the problem is beyond the capability of individual landholders to control.

"The Australian Plague Locust Commission is responsible for spraying in western NSW."

Mr Eggleston said early reporting of locust activity would ensure action could be taken before the locusts could develop wings and begin flying.

"We could see some surviving locusts flying in the near future and we could even see some swarming if there is a significant shortfall in reporting," he said.

"If locusts swarm as they did in 2004 and 2005, they could move hundreds of kilometre a day, chewing their way through massive quantities of green feed.

"Just ten hectares of banding locusts become a one square kilometre swarm that can consume 10 tonnes of valuable pasture or crop every day.

"Controlling swarming locusts with aerial spraying is difficult, expensive and nowhere near as effective as controlling banding locusts, and in many cases is not even an option.

"This is why it is so important to look, report and treat banding locusts now."

Contact your local RLPB, or visit www.dpi.nsw.gov.au/info/locusts