The South Australian Farmers Federation president, Peter White, says locusts are starting to eat crops before they can be harvested.
Aerial spraying was cancelled on Friday and Saturday because of rain but will continue through the week.
Mr White says farmers still hold high concerns about locusts damaging their crops.
He says landowners need to ensure they are taking every precaution to ensure their crops are not damaged.
“Certainly the landowners are very concerned that they are actually flying and getting into their crops and eating them now so you can’t just stand by and see it be destroyed without doing something,” he said.