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  • Writer's picturePatrick Dawkins

Hunter-Reilly’s Cost-Effective Formic Formula


Necessity is the mother of invention, so the old proverb goes, and it has been the case at Hunter-Reilly in the Wairarapa where, faced with a shortage of their regular formic acid varroa treatments they were forced to look elsewhere. That shift in gaze only needed to go as far as a couple of sample boxes of Nassenheider evaporators in the corner of their shed and the units have been so effective in trials that Hunter-Reilly are planning on importing a whole container-load from Europe, which owner Stu Ferguson hopes other beekeepers can help fill.

While Ferguson has been mightily impressed by the effectiveness of the German-made Nassenheider applicator and its ability to offer extended varroa control by distributing formic acid to his hives over a three week period, it is unregistered in New Zealand.

“We got some great results in the season just been, but that’s just us doing our own thing on a few trial apiaries as very much an own-use system,” the Wairarapa beekeeper says.

He had a few boxes of Nassenheider pro units gained years ago as part of his product development with the Hive Doctor brand he founded, and has since sold. He also had some hives that were prone to high varroa re-infestation rates which they could not get on top of it without using a formic solution.

The Nassenheider Professional formic acid dispenser. It's first in first served when it comes to getting one says Stu Ferguson as he plans to import one container load.

In previous seasons they had used the Formic Pro “pad” method as a get out of jail card in varroa mite problem areas, with the pads sitting directly on the top bars of the frames. However, when Ferguson had trouble sourcing cost effective Formic Pro options at the end of 2023-24 season, the Nassenheider applicators he had been given to trial some time before became the most cost-effective method to apply formic acid in a sustained manor.

“We ran out of our formic-pro in January just as we needed it the most, so we had no option but to reluctantly trial the stored Nassenheider units that we had no experience or feel for,” he explains.

There are several forms of Nassenheider applicators available, some which hang into beehives in the place of frames, but Ferguson decided on the widely used and mature “Professional” design, which is placed on top of the hive. At Hunter-Reilly they have cut down old boxes to a height of 75-80mm to house the applicators in. It contains a sump which holds around 240ml of formic acid solution, which then drips down a wick and onto a pad from where it evaporates over a period of two-three weeks.

“There are three wick options available and if we use the correct wick for the time of year we can get 20 days out of it, so almost a whole brood cycle,” Ferguson explains.

“We are so impressed. We had a couple of areas that were loaded with mites and getting reinfestation from neighbouring hives. We couldn’t get on top cost-effectively and it was causing headaches. Now, it is like a light has been switched. We are on top of the mites for under one dollar per treatment and we are getting results. It has been simple really.”

Stu Ferguson and his team at Hunter-Reilly in the Wairarapa have been so impressed by the success on Nassenheider units in controlling varroa that they plan to use them across the board next season and reduce their spending on varroa control.

While there is some negativity around formic treatments and queen loss, the Hunter-Reilly hives have not observed any such problems when using the Nassenheider system.

Entering next season, Ferguson plans to use the Nassenheider applicators on all of his hives. That will mean importing around 1500 more of the units into the country. If he is going to bring in that many, he figures he might as well cast around beekeepers to see what interest there is in filling a container and distributing at the lowest possible price to provide a cost-effective hive treatment for many.

“Varroa is the number one threat to bee health, it keeps a lot of beekeepers up at night, so I thought it only fair to share our experience and offer the opportunity for others to be part of a collective effort,” Ferguson says.

For any beekeepers who contact him and help fill the container, it is up to them to do their own research and determine how the applicator can best assist their beekeeping, he stresses. He also points out that they have been using stringent adherence to personal safety procedures when handling acid solutions, and that he is open to advising any formic acid users on best safety practices.

Ferguson has received assurance from the Ministry for Primary industries that import of the Nassenheider applicators alone, without any treatment compounds, is above board. There is space for 4500 more units in the container (less than 1% of hives in New Zealand), so beekeepers should get in touch promptly if they want to be included.

If he can fill a container, expected cost of each unit is about $17, a cheaper price than which they are retailed in Europe, and they will be available in in boxes of 23 or 46 for commercial beekeepers, with first in first included. From there each hive treatment has been costing Hunter-Reilly in the 30-40c in consumables and they have been carrying out three or four treatments a year (two after honey harvest, autumn, and one or possibly two in spring), alongside other organic methods.

“I figure if I am going to be bringing some of these units into the country for my own use, why not try to help other beekeepers along the way by offering them the opportunity too?”

Any beekeepers wishing to get more info or join the order can contact Stu Ferguson via email


More info on Nassenheider units:


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