Scientists are expecting more bee colony deaths due to a killer parasite that has become resistant to a pesticide used to control it.
The varroa mite was first identified in the North Island 10 years ago and is expected to wipe out all wild bee colonies.
One beekeeper says about 800,000 bees have gone missing from 40 of his hives in suburbs of Auckland in the past month.
Tests on the dead hives will be carried out on Tuesday.
Mark Goodwin, a scientist at Plant & Food Research, says when varroa mites kill a colony, the bees simply leave the hive to die.
"Previous to now we haven't had a lot of deaths due to varroa because beekeepers know how to treat their hives and the treatment's been very effective.
"But we're starting to develop resistance, so we're expecting especially in the Auckland region and into the Waikato to start to see quite significant deaths."
Dr Goodwin says beekeepers should be using chemicals in a different way than they are used to, to try to control the parasite.
Beekeepers Association chief executive Daniel Paul says although the disappearance of bees from hives it is worrying, it is not unexpected.
Mr Paul says the industry was aware when the mite entered New Zealand that it would take 10 years before treatments used to control it would become ineffective.
