Three out of every four treatments reduced mite load. Across four apiaries and 20 colonies, we logged 69 treatments between April and September, and averaged across the whole season, a single ThermaHive treatment cut mite counts by 51 percent, right in line with one strip of Formic Pro.

On September 9, 2026, Storm and a surveyor from the National Honey Bee Survey (NHBS) came out to our research apiary and pulled frames from five of our ThermaHive-treated hives, alongside several of our chemical-control hives for comparison. (We left TH-4 and TH-5 out of sampling: both are carrying small colonies after queen issues earlier this season, unrelated to treatment, and we wanted to leave every bee they have in place for overwintering.)

The result, by Storm’s own account, was one he’d never seen before in all his years of beekeeping: neither he nor the NHBS surveyor could find a single mite on the larvae pulled from any of the five ThermaHive-treated hives, to the naked eye. Finding one clean hive out of five happens now and then. Finding all five clean does not.

Larvae sampled from a ThermaHive-treated hive, September 9, 2026

It’s too early to draw firm conclusions. The samples are headed to the University of Maryland for full lab analysis, including virus screening and pollen evaluation, with results expected in November. But one hypothesis worth naming out loud: this pattern is consistent with mites in the hive being sterilized by treatment rather than simply killed off outright, unable to reproduce even where a few remained. If that holds up under lab analysis, it would be a meaningful finding beyond a straightforward mite-kill count.

We don’t expect anyone to take a single season’s numbers on faith, so here’s how our average per-treatment mite kill this year compares to common treatments beekeepers already use: our field data this season, alongside Randy Oliver’s published benchmarks for the rest.

Heat lands right around one strip of Formic Pro, with none of the residue, none of the resistance risk building up in your mite population, and no waiting period before you can pull honey.

We also ran our season’s numbers through Randy Oliver’s Varroa Model, plugging in our treatment results to see how a ThermaHive-treated colony’s projected mite trajectory compares to an untreated or chemically-treated one across a full season.

We tracked phoretic mite load in seven colonies from late April through early September. Five of them were under 2 percent by September 2nd. The other two spiked hard in August before settling back down to just under 4 percent by season’s end, and we know exactly why. In both hives, the queen had moved up into the honey super and started laying there. ThermaHive’s heater treats the brood box, not the supers, so that batch of brood went untreated and its mite counts climbed until it emerged. Once it did, both hives came back down on their own.

It’s a good reminder that heat only works where it reaches, and it’s exactly the kind of edge case we’re designing around for next season.

And so everyone knows we didn’t just get lucky, or that we’re somehow immune to varroa: we lost one of our control hives, B-1, to varroa this season. Coming into late August, B-1 had already been through three oxalic acid treatments. On August 24th, a mite wash came back at 150 mites per 240 bees, a load of roughly 62.5 percent. That same day, we treated with oxalic acid and thymol. By September 2nd, the colony had been slimed out by small hive beetle and had to be condensed. As of September 9th, B-1 had officially collapsed to varroa.

B-1, slimed out by small hive beetle, September 2, 2026

Every heat-treated colony in the same yard made it through the season.

ThermaHive doesn’t just get tested in our own apiaries. This season, three independent testers ran units in their own hives, under their own conditions, hundreds of miles apart from each other and from us. Here’s what they found.

Our tester in North Carolina ran more ThermaHive treatments than anyone else in the program this year: 23 logged between May and August, with results that held up statistically (p = 0.00005). On average, each treatment cut mite load by 71 percent. His best single session brought one hive from 7.87 percent down to 0.26 percent, a 97 percent reduction. By season’s end, 9 of his 10 treated hives were under the 2 percent threshold, and 5 of those were at zero.

Part of why his numbers stand out is how he ran his treatments. Rather than treating a hive once and waiting to see if it held, he came back and treated it again within a week or two, especially on his higher-count hives. Treatment pairs run 7 to 14 days apart netted a 75 percent reduction on average, ahead of what a single treatment brought on its own (62 to 65 percent). It’s a simple change in approach, but it’s shaping up to be one of the bigger levers we have, and it’s the direction we’re steering our recommended protocol for next season: fewer single “treat and wait” applications, more short-interval, back-to-back ones.

Our tester in New Jersey was working with the heaviest mite load recorded anywhere in the program this season. Her hardest hive tested at 21.00 percent in July. One ThermaHive treatment brought it down to 8.06 percent; a second, run eight days later, brought it to 4.6 percent. All four of her treatments reduced mite load, brood and queen were unchanged throughout, and she still pulled more than 70 pounds of honey.

Our tester in Georgia had a rough start. A first attempt was cut short by a generator shutoff and the mite load actually rose. But a full 3-hour treatment at 112°F on August 26 brought his hive from 9.2 percent down to 2.3 percent within five days, a 75 percent reduction, landing just above the treatment threshold.

While we were out in California this month, we got the chance to sit down with Randy Oliver on September 7th and walk him through ThermaHive in person. He’s agreed to test it himself in his own operation.

More on that conversation, and on what he thinks, in our next update.

None of this season happens without Storm. He gave us the bees to start with, taught us how to actually be beekeepers, and then spent the season patiently suffering through all 51 mite washes we put him through, 48 across our seven ThermaHive colonies and 3 more on the controls. We are endlessly grateful, and so are the bees.

Daniel, Lexi, and Storm