They expect it could take between five and 20 years for some flowering gums to fully recover, and to produce enough nectar and pollen to feed the bees.
Stephen Targett from the NSW Apiarists Association said thousands of hives — housing many millions of bees — had also been destroyed.
South Australia has reported losing 3,000 hives on Kangaroo Island and in the Adelaide Hills fires before Christmas.
While the beehives can be rebuilt easily, the remaining bees will be weak and hungry.
Mr Targett said the South Coast bushfires had a massive impact upon bees. "Beekeepers had hives among grey ironbark [near Bermagui] when the fires came, and they worked all night to move the bees out of there to blackbutt [forests near Eden]," he said."Then a few nights later, they had to come and move them because that resource was getting burned as well."
After years of drought, trees had stopped flowering in parts of the NSW South Coast. Illawarra beekeeper David West suggested gardeners grow more flowering plants and set up birdbaths for bees.