Hawke's Bay Beekeepers says some apiarists could go out of business unless new control methods are found very soon for the varroa mite.
President John Berry says there's increasing resistance to chemical treatments.
For the first time since varroa was detected in New Zealand 11 years ago, he says, he has found large numbers of the mite in hives in early spring.
Mr Berry says he's taking part in a commercial trial using bees bred by Plant & Food which are resistant to varroa, but it won't be known until next autumn whether they have been of any benefit.
Plant & Food Research bee scientist Mark Goodwin says that when chemicals were first used in New Zealand, almost all the varroa mites would die.
But in the last trial he carried out, almost 80% of the varroa survived.