NZ Colony Loss Survey Results Revealed – Losses Climb as Varroa Bites

NZ Colony Loss Survey results are here and they confirm what many beekeepers suffered through in winter and spring 2025. We sit down with Survey lead and Bioeconomy Science Institute principal scientist Pike Stahlmann-Brown to dive into what beekeepers have said about winter losses.

Apiarist’s Advocate: The 2025 NZ Colony Loss Survey results have just been released. What are the headlines from the latest survey?

Pike Stahlmann-Brown: The story on over-winter losses in 2025 is not so great, with an overall loss rate of 12.8%. This loss rate is similar to the 2023 loss rate of 12.7%, but it’s up rather sharply from the 2024 loss rate of 10.8%. In 2024, we saw a big decline in colony losses due to varroa, but that was completely erased in 2025. In fact, we had more losses attributed to varroa over winter 2025 than in any previous year of the survey.

Pike Stahlmann-Brown, author of New Zealand’s Colony Loss Survey.

AA: That matches the anecdotal evidence, as queens and nucs were hot property in spring 2025 as beekeepers looked to recover. So, what was the loss rate to varroa in 2025?

PSB: Based on reports from about 2,000 beekeepers, 7.0% of all healthy, living colonies entering winter died because of varroa. In 2024, it was 4.6%. That’s a big jump, and one that makes me worry where varroa losses are headed in the future.

AA: Are beekeepers treating varroa any differently from in the past? 

PSB: The use of formic acid, tau-fluvalinate, oxalic strips/staples, and oxalic sublimation/vaporisation were way up for commercial beekeepers – to the highest levels we have ever recorded. If people are using these products for the first time, there could be a bit of learning and experimentation taking place. I would note a couple of things, though. The first is that their use of amitraz and flumethrin was more or less unchanged since 2024. That means that commercial beekeepers are using a wider variety of treatments. The second is that when we asked commercial beekeepers how successful these treatments were, not a single treatment was widely perceived to be as effective as it was in 2024.

There’s a similar story for hobbyist beekeepers: the use of formic acid, oxalic strips/staples, and oxalic sublimation/vaporisation were all up (not so for tau-fluvalinate), and the overall perceived effectiveness of most treatments was down.

AA: Are there any other stark results when comparing hobbyist and commercial beekeepers?  

PSB: Just that loss rates attributed to varroa were about 26% higher among hobbyist beekeepers than commercials. We unpacked this a little bit and found that hobbyists are 3.5 times as likely as commercials to treat varroa only once during the season and 2.4 times as likely to use the same product every time they treated varroa.

AA: As I recall, the 2025 survey also asked about sources of beekeeping advice. What did that uncover?

PSB: This question had two parts to it: Do you believe that a given source has relevant information about beekeeping? If so (and only if so), how much do you trust that source of information? Hobbyists thought that peers/mentors, beekeeping clubs, and beekeeping magazines like Apiarist’s Advocate were the most relevant sources of information, and they also had high trust in all of these sources (although they ranked New Zealand Bee Health & Biosecurity (NZBB) and scientists even higher in trust). Commercial beekeepers thought that peers/mentors, beekeeping magazines, and industry groups were the most relevant sources of information, and they thought that scientists, NZBB, and beekeeping magazines were the most trustworthy sources of information. On the other end of the spectrum, websites, social media, and AI were perceived as being in the lower end of the trust spectrum.   

AA: Glad to hear it! But, what do you do with that information?

PSB: I think it’s important for potential sources of advice to know how they’re perceived. Take scientists as an example: We’re highly trusted as a source of information about beekeeping, but less than half of beekeepers think we have relevant information. It feels to me like we can do better in making scientific knowledge readily available.Also, I recently attended the COLOSS meetings in Austria, and the international COLOSS monitoring group has decided to adopt a similar question. It will be useful to see how different sources of advice are perceived in different countries so we can learn good practices from one another.

AA: You would be in your element there – what else was discussed at the COLOSS meetings?

PSB: More than 42,000 beekeepers in various COLOSS member countries (including New Zealand) completed a colony loss survey in the last year. The results from the 2024/25 northern hemisphere winter haven’t officially been released yet, so I won’t go into too much detail, but suffice to say that our loss rate of 12.8% is envied by a lot of COLOSS countries, some of which experienced loss rates between 30% and 40%. Among 34 countries for which results were available, only one had lower loss rates than New Zealand.

After the COLOSS meetings, I met with the directors of the colony loss survey in the Czech Republic, because I think their surveys are among the best in the world. One reason is that they had over 9,000 beekeepers complete the winter 2024/25 survey, compared to fewer than 3,000 beekeepers the year before (meanwhile, our numbers have dropped a bit in recent years).

Another thing that they do really well is presenting results at a local level. Whereas we report loss rates for the Upper North Island, Middle North Island, and so on, they have been able to report at something closer to the postal code level. New Zealand Beekeeping Inc president Jane Lorimer raised the idea of doing something like this a few years ago, and I wanted to get some practical advice on how to make it work in New Zealand.

AA: Fresh ideas raised … sounds like a productive trip! 

PSB: It really was. On top of that, we’re working on putting together some proposals for international funding to support research across countries. For example, there’s a lot we need to know about how changing climate will affect floral resources and honeybee health, and we can lean into the COLOSS research network to improve outcomes for beekeepers everywhere.

AA: Ok we’ve covered a lot, but there is plenty more in the full NZ Colony Loss Survey 2025 results. Where can people get them? And is there anything else you want to add?

PSB: Check out the neat infographic running alongside this story for an easy-to-consume look at the 2025 results, or visit the Ministry for Primary Industries website for a detailed data summary.

An illustration of “area-code” level colony loss reporting from Czech Republic. Should New Zealand report honey bee colony losses to this level? Email Pike Stahlmann-Brown at surveys@landcareresearch.co.nz with your thoughts, and any further ideas to improve the survey.

The NZ Colony Loss Survey evolves over time, so I’d like to ask the readers of Apiarist’s Advocate to send me ideas for the next survey. I tasted some awesome mead when I was in the Czech Republic, and I brought two bottles of my favourite mead from Kubešova back. One of them is for me, but I’ll send the other bottle to the beekeeper who sends the best idea to surveys@landcareresearch.co.nz by 30 April 2026.

The New Zealand Colony Loss Survey has been conducted annually since 2015 by the Bioeconomy Science Institute on behalf of the beekeeping industry and the Ministry for Primary Industries.