Almost 13% of New Zealand’s bee colonies lost last winter, with varroa mite a big factor

Almost 13% of the country's bee colonies were lost last winter, about 63,000 colonies. Photo / Brett Phibbs

By Charlie Dreaver of RNZ

It’s estimated that almost 13% of the country’s almost half a million bee colonies were lost last winter – equivalent to about 63,000 colonies.

That’s according to the annual Colony Loss Survey by researchers at the Bioeconomy Science Institute (BSI).

Almost 2000 beekeepers with more than 148,000 colonies took part in the study.

One big takeaway was the uptick of colonies dying from varroa mite – an external parasite that can weaken or even destroy entire colonies.

The mites were thought to have caused the loss of 7% of all healthy, living colonies over the winter, with losses attributed to varroa especially high in the lower South Island.

BSI principal economist Pike Stahlmann-Brown said it was a question the institute had asked beekeepers since 2017.

“For queen problems, starvation problems and wasps, the numbers are always about the same; they just don’t really change very much.

“But for the varroa mite, it has been increasing every single year until 2024, when we saw a dip, and 2025 it’s back where it was before.”

According to the survey, losses from varroa were more than all other causes combined.

Gisborne-based commercial beekeeper Barry Foster said it was getting more and more difficult to control the mites, with re-invasion being a major problem.

“It’s a result of probably beekeepers not generally treating at the same time, which would be good to do if they could do it in a given area, but it’s a matter of, you know, connection, a collaboration to do that sort of thing,” he said.

Foster added that any hive that didn’t get treated at the right time became what he described as a “varroa bomb”.

He noted this was a problem not only for the honey industry but also for the whole country, because beekeepers massively contributed to the economy by pollinating plants for the horticulture sector.

The study also pointed out that beekeepers were the unsung heroes of wasp eradication – killing more than 12,000 nests between spring 2024 and winter 2025.

In fact, five beekeepers estimated they eliminated at least 500 wasp nests during the previous season.

– RNZ