Low to medium levels of locust activity have been recorded in the central west during autumn, with some egg laying.

The optimum time for control is when the locust nymphs are forming bands on the ground.

This is usually around three weeks after hatching - early detection and reporting is essential.

Central West Local Land Services senior biosecurity officer Craig Ridley is encouraging people to be aware and report any locust activity to Local Land Services.

"We anticipate that with favourable conditions, hatchings could occur by mid-September in most areas," Mr Ridley said.

"This however is only a guide and activity could occur before or after this time subject to environmental conditions."

Areas of known activity include Condobolin to Trundle, Hermidale to Nyngan, Wellington to Dunedoo and Lake Cargelligo.

"We are aware of some egg beds in these areas but there may be others that remain undetected at this point," Mr Ridley said.

Landholders should report any locust activity to their nearest LLS office.

This will allow staff to carry out an inspection, advise on the relevant control options and issue chemical if warranted.

"Once locust reach maturity and start to fly, control becomes very difficult and costly.

"Early ground control is paramount to minimise the impacts to crops and pasture."