Hundreds of beehives on the NSW south coast have been sprayed with poison, with a major honey producer left devastated and a harvest ruined.

Police said about 750 beehives were poisoned on properties near Batemans Bay causing about $150,000 worth of damage.

Wendy Roberts from Australian Rainforest Honey at Sunshine Bay, which provides honey to Woolworths around the country, said about 240 of their 5000 hives had been sprayed, killing all the bees inside.

Mrs Roberts said her husband Pat discovered the poisoned hives at two of their sites yesterday morning.

The honey on some of the hives was ready to be harvested this week, but is now contaminated.