While locusts munch down on the mid-row grass in Clare Valley vineyards, grape growers are contemplating their options.

Because of a law requiring a 3km gap between sprayed areas and residential housing, anxious growers are unable to spray their crops from the air. But if they are going to take this action, it is best done within the next two weeks, when the newly hatched locusts will still be unable to fly.

The message from Phil Saunders, of South Australia's Department of Primary Industries and Resources, was to keep on hoping that the locusts do not eat the vine leaves..