"We put them in that forest because it was well protected from the weather and out of the extreme cold. They were also put there because the site was easy to access," Mr de Wit said.
It was a relatively new wintering site for the company and in summer the light blue-coloured hives would be placed where manuka was flowering.
"This is unfair and unacceptable. It hurts our investment when this happens and we would like our hives back."
He hoped the offer of the $20,000 reward would lead to information that would enable them to get the bees back or prosecute the offenders.
Mr de Wit had no idea where the hives could have been taken or at what time the heist would have occurred.
A substantial truck would have been needed to shift all the hives, he said.
"In a closed truck they could have been transported six hours away."
Apiculture New Zealand said beehive theft was happening with increasing regularity and the organisation wanted to work with police to address the problem.
Ministry for Primary Industries recorded a record honey season for 2014/15 with an estimated 19,700 tonnes produced.
Beehive thefts became such a problem last year that Kawakawa Police devised a plan specifically aimed at catching offenders as they transported stolen hives around Northland by night.
Police launched a Northland-wide campaign in May last year to stem a spate of beehive thefts fuelled by soaring demand for manuka honey. It asks members of the public to call *555 from their cellphones if they see any suspicious movement of beehives, such as being transported late at night. Most legitimate movement of hives occurs around dawn or dusk.
Anyone with information on the latest theft from Topuni can contact Whangarei Police on (09) 430 4500 or the Watson & Son lawyers on (04) 473 7537.