SWARMS of locusts are sweeping across south-western NSW.
A "low density" swarm seen in the Condobolin district measured about 6km long, and 170m wide, the state government said on Tuesday.

Low to medium density swarms have also been spotted in the Wagga, Gundagai and Narrandera districts.

Primary Industries Minister Ian Macdonald said about nine planes were on standby to treat the swarms if they grew larger or thicker.