Landholders have been urged to be on the lookout for locust activity.
Riverina Local Land Services suspects dormant locust eggs may form localised bands when they hatch later this month. The LLS said eggs in areas north of Narrandera and around Jerilderie were a cause for concern.
Senior biosecurity officer Toby O'Brien urged landholders to be vigilant.
"We did have some eggs laid in autumn that have hibernated for winter, and these will start hatching from late September onwards," Mr O'Brien said. "Landholders are our eyes and ears on the ground, and reporting locust activity early allows us to be on the front foot with them."
Adult plague locusts usually lay eggs on compact roads next to crops, tree lines and farm buildings. Mr O'Brien said the best time to control outbreaks was when locusts begin to "band".