Frequently Asked Questions

In the 2026 field season, ThermaHive reduced mite load by an average of 51% per treatment across 49 paired mite washes on 16 colonies, read 14 to 28 days after treatment (95% CI 31 to 65%). Across the full set of 55 paired washes, mite load fell after 41 of them.

Our best single session was a 97% reduction, from 7.87% to 0.26%, at an independent tester’s apiary. The 51% figure is the number to plan around.

See the full 2026 results, including how we measured and the fourteen washes that came back higher.

About the same as one Formic Pro strip. Using Randy Oliver’s published benchmarks: oxalic acid with brood present kills about 30% per application, one Formic Pro strip about 50%, two strips about 80%, Apiguard about 90%, and Amitraz strips about 95%.

See the full comparison against traditional treatments.

Because you can use it whenever you want. Amitraz kills more per application, but resistance is now widespread, and every chemical treatment carries temperature limits, honey super restrictions, or waiting periods that decide for you when you can treat.

Heat has none of those, so you can repeat it on schedule rather than squeezing it into a weather window.

That is the main advantage of heat. Most of a colony’s mites are under cappings where contact treatments cannot reach them. Published thermotherapy studies report 99.5 to 100% mortality of mites in sealed brood at treatment temperatures (Bičík et al., 2016; Goras et al., 2015).

There is no known mechanism for it. Varroa develop chemical resistance through genetic mutation, but heat works by exceeding the mite’s physiological temperature limit, which is not something a population can evolve around the way it evolves around a molecule (Bičík et al., 2016).

This is the single strongest argument for thermal treatment, and it gets stronger every year that chemical resistance spreads.

Yes. Independent testers in North Carolina, New Jersey and Georgia ran their own units on their own colonies in 2026. The North Carolina operation logged a 71% average reduction across 23 treatments (p = 0.00005), with nine of ten hives under 2% at season end.

Separately, the National Honey Bee Survey sampled five of our research colonies on September 9, 2026 and found no mites in the field samples. Full lab analysis from the University of Maryland, including a virus screen, is expected in November 2026.

Not yet. The 2026 season is our own field trial, run alongside chemical control groups and independent testers, and we publish the full dataset including the treatments that did not work.

The underlying science of thermal Varroa control is well established in the peer-reviewed literature, and we cite it.

Fourteen of 55 paired washes came back higher. The 55 is every treatment with a wash on both sides of it, out of 69 logged across our apiary and the independent testers. How we measured explains the one wash we left out.

Some have a clear cause. Two were hives where the queen had laid in a honey super, which runs cooler than the brood boxes the system regulates to, so the mites up there got a weaker dose. Several more were early-season treatments, from the weeks when we were still working through hardware faults and settling the program on the V1 prototypes. We count them anyway.

Heat only works at full strength where the system holds it, and no treatment fixes a queenless or failing colony. We publish all fourteen.

No. There is a real temperature window between the two. Mites die between 104 and 113°F (40 to 45°C). Adult workers tolerate up to roughly 118°F (48°C) on short exposure.

ThermaHive is run at 108 to 112°F (42 to 44°C), with a firmware ceiling well below the point where bees are at risk, and it holds that setpoint tightly. Our best recorded hold averaged 112.03°F (44.5°C) against a 112°F (44°C) setpoint, with 99.6% of a three-hour treatment inside plus or minus 2°F (1.1°C).

Four independent layers.

1. Firmware ceiling. The heater cuts the instant a reading crosses the configured maximum.
2. Fault blocking. Invalid or missing sensor data blocks operation rather than defaulting to heat.
3. Factory overheat protection at the heater. The heater assembly carries its own 100°C cutout and 112°C thermal fuse, installed by the manufacturer and independent of the controller, so it works whether or not the controller is alive.
4. Hardware watchdog. If the processor ever stalls, the watchdog resets the controller, and opening the heater relay is the first action it takes on restart.

The system is built so that every failure mode ends with the heater off.

Not at our protocol. The published risk comes from long exposures: Goras et al. (2015) saw larval mortality beyond four hours, and Appel and Büchler (1991) recorded harm to brood emergence at 45°C (113°F). ThermaHive is run for two to three hours at 108 to 112°F (42 to 44°C), below both of those thresholds.

Our colonies with the longest treatment histories kept healthy brood nests through the season, including one inspection with twelve frames of capped brood and six of young larvae. Brood inspected after repeated treatments has been white, glossy, and normally capped.

Follow the recommended time, temperature, and frequency guidance. Any hive damage from settings you have changed yourself is your responsibility.

So far we have not noticed any problems with the laying pattern of a treated queen, and we have not lost a queen to a treatment. Queens that were still capped in their cells when a treatment ran have emerged normally and are laying.

We will keep monitoring this long-term. To be safe, we would not recommend treating a hive with ThermaHive if you are actively breeding from that queen. Treat the production colonies and leave the breeder alone.

Through the entire 2026 season, we have not seen any change in the queens treated with ThermaHive or in their laying pattern.

Per Allan Storm, Master Beekeeper and Maryland State Bee Inspector, all of the ThermaHive-treated hives show normal laying patterns with good larvae, and there has been no evidence of brood being dried out.

In fact, two of our hives had queens that were still in their cells when treatment ran. Both have since emerged and are laying, and those are two of our biggest hives.

That is field observation, not a laboratory sperm viability assay. This is something we will keep monitoring long-term by counting frames of brood and larvae at every inspection, because a decline in laying is the first place damage to a queen’s stored sperm would show up.

Until we have more seasons of data, we would not recommend using ThermaHive on a hive whose queen you are actively breeding from. That is caution, not evidence of a problem.

None. Zero of 20 ThermaHive-treated colonies were lost across four apiaries and 69 treatments in 2026.

One of six chemical control colonies was lost, after three oxalic acid treatments failed to hold its mite load down.

We did not see absconding, bearding or a drop in foraging in any treated colony during our 2026 field trials.

On the published chemistry, no, not at any realistic number of treatments. The thresholds that define “raw” honey are measured in days of continuous exposure, not minutes.

The enzyme half-life. Invertase, the enzyme used as honey’s heat-damage marker, has a half-life of 9.5 days at a continuous 104°F (40°C; White, Kushnir and Subers, 1964), which is 227.5 hours of cumulative exposure. In our trial the honey super logged 2 hours 20 minutes above 104°F (40°C) per treatment. At that rate it would take roughly 98 treatments to halve invertase activity. A full season is six.

That 98 figure is a linear extrapolation from a single published half-life, not a measurement of our honey.

Here is what the published standards actually require:

In our own live testing, a three-hour treatment at a 112°F (44°C) setpoint crossed 104°F (40°C) at about the one-hour mark and stayed above it for 2 hours, 19 minutes and 55 seconds.

We intend to send samples of our honey to a third-party lab for official enzyme testing. We will update this answer with the results either way.

The practical result, measured rather than modelled: seven colonies heat-treated all summer produced 250 lbs of honey in 2026.

Not in our experience. Seven colonies heat-treated all summer at the research apiary produced 250 lbs of honey in 2026.

An independent tester reported the same thing from her own yard: 70 lbs from her ThermaHive-treated hive, against a typical 50 to 70 lbs for an established colony, and very similar to what she took off her other hives of the same size that season.

Not in our experience. We did not notice any change in the honey from our treated colonies, and we thought it was very good.

Yes. There is no harvest restriction, no waiting period and nothing left behind, because nothing is applied. This is one of the practical advantages over formic acid and thymol, which both restrict when you can treat relative to harvest.

You can treat and harvest on your own schedule, which improves your chances of multiple pulls in a season.

No. Heat is not a substance. Nothing accumulates in your comb, which matters because wax holds miticide residues for years and those residues are themselves implicated in queen and brood problems.

No. You may find the wax slightly softer after a treatment, but a treatment does not get hot enough to melt it. Beeswax melts at around 140 to 150°F (60 to 66°C), and treatments run at 108 to 112°F (42 to 44°C).

Swap the blank insert for the heater insert, set the Top Box on the hive, and start the session. The hive stays closed. No frames come out, no bees are moved, no smoke, no suit necessary. The system holds temperature for the programmed duration, runs a cool-down, and logs the session.

No. The sensor is placed once and stays. The heater installs from the bottom. The treatment runs with the hive closed.

About three to four hours: 30 minutes to an hour of preheat, then two to three hours at temperature. Our standard is 112°F (44°C) held for three hours.

You do not need to be there for any of it. Set it up, start the session and walk away. The controller brings the hive up to temperature, holds it, runs the cool-down, shuts the heater off and logs the whole session to the SD card. In our own apiary we would routinely start a treatment, leave, and not come back to that hive until a few days later. If something trips a safety limit, the heater is already off by the time you would have noticed.

Preheat is the part that varies, with ambient conditions, colony size and how full the box is. The treatment clock does not start until the brood nest is at temperature, so the hold you get is the hold you set.

We recommend 2 consecutive treatments, spaced 7 to 14 days apart, each brood cycle. A worker brood cycle, egg to emerging bee, runs about three weeks.

Smaller colonies with low starting mite counts, or VSH stock, can often manage with 1 treatment per brood cycle. Large colonies may need up to 3 consecutive treatments to bring mite counts down. Let your mite washes guide you, and treat again sooner if a wash comes back above the seasonal threshold.

Why spacing matters: mites sealed in capped brood during the first treatment emerge within the next 1 to 2 weeks, and the follow-up treatment catches them.

Over time you should be able to treat less often. Research suggests that as the mite population comes down, you can consolidate to one treatment per brood cycle, since there are fewer mites to deal with. Because heat carries no honey, weather or waiting restrictions, the schedule is yours to set rather than something the label decides.

The working range is 108 to 112°F (42 to 44°C) for two to three hours. Within it, we recommend 112°F (44°C) for three hours.

A hive does not heat evenly. Some parts come up to temperature faster than others, so the reading at the sensor is not the temperature everywhere. Treating at 112°F (44°C) makes it likely that every part of the hive gets to at least 108°F (42°C). Running for three hours makes it likely that every part spends at least two hours at 108°F (42°C) or above, including the parts that are slowest to warm.

112°F (44°C) for three hours was also the best performing combination of the protocols we ran in 2026, at our research apiary in Maryland. Independent testers in other climates have done well lower in the range, around 109°F (43°C) for about two hours.

Your own hive and climate still matter: how full your boxes are, how much comb and honey the heat has to warm, and how hard your colonies fight it. Wash before and after, and adjust based on what you see. Because every treatment is logged, you can tell whether it is the setting that needs changing or the delivery that came up short.

Spring for early buildup support, summer through the peak, and a fall window before winter bees are raised, which is the treatment that matters most for overwintering.

Seasonal action thresholds: 1% or higher in spring, above 2 to 3% at peak summer population, 2% or higher in late summer and fall.

Do a mite wash. We recommend reading efficacy from a wash 14 to 28 days after treatment, which is Randy Oliver’s guidance and what our own numbers are measured on.

A wash taken immediately after a treatment reads differently, because mites emerging from brood have not yet appeared in the phoretic population.

It should not be the norm. A heat treatment is meant to reach the mites in the brood as well as the ones on adult bees, so when a count rises there is usually a contributing factor. The common ones: the queen was laying in a honey super, which runs cooler than the brood boxes the system regulates to (two of our 2026 rises were exactly this); the session did not reach or hold temperature, which the log will show; a very large, heavy colony that runs cooler and takes longer to come up; or brood timing, since a wash only counts mites on adult bees and a colony sampled mid-emergence releases whatever survived under the cappings into that count all at once. Mites also drift in from neighbouring colonies, especially in late summer.

Every hive is different, and sometimes a count rises with no reason we can point to. Check the session log and what the brood is doing before drawing conclusions from a single count, and if the wash comes back above the threshold for your area and season, treat again. See Treating Across a Season for how brood timing shapes what a wash can tell you.

Then those mites are getting a weaker dose than the ones in the brood boxes. Heat does rise into the supers, but the system regulates to the sensor in the brood nest and a super above it runs several degrees cooler. In our logged runs a super peaked at 109.6°F (43.1°C) and averaged 106.9°F (41.6°C) while the brood nest held 112°F (44°C), and depending on your hive configuration a super may never reach the lethal window at all.

Two of our 2026 treatments showed a higher count afterward for exactly this reason. Run a queen excluder, or configure the super as a brood box for the treatment so it is inside the regulated zone.

Not for residue reasons, since there are no chemicals involved. Whether to remove them for thermal reasons is something we are still figuring out: most of our 2026 treatments ran with supers on, some ran with them off.

One thing we do know: if a colony has brood in a super, leave it there until that brood emerges rather than pulling frames of developing bees. Brood in a super sits above the area the system actually regulates.

Yes to the entrance reducer. We recommend one for every treatment. It keeps warm air from escaping at the entrance, so the fans can spread the heat evenly across the box instead of the colony losing it out the front, and it gives you the most even heat distribution.

You do not need to add humidity. The sensors log it throughout the treatment, but no water or humidity source is part of the protocol.

Yes. The system fits standard 8-frame and 10-frame Langstroth equipment.

ThermaHive is designed to fit a standard wooden Langstroth hive, 8-frame or 10-frame. It is also compatible with other hive types built to similar dimensions, including:

• Apimaye insulated hives, with a slight modification. Add a note at checkout and we will add a free piece of wood to both long sides of your bottom box, for a stable fit on the Apimaye base.
• Polystyrene and other insulated Langstroth-size hives
• Plastic Langstroth-size hives

In general, ThermaHive fits almost any hive with dimensions similar to a standard Langstroth, as long as the hive’s bottom board or stand has a screened opening, or can be given one.

Not sure about your hive? Email support@thermahive.net with its measurements and a photo of the bottom board, and we will let you know.

No. You can leave your unit on the hive full time. Leaving it in place is a supported way to run it, not a workaround.

The bottom treatment frame stays on each hive. The heater insert, diffuser and controller rotate between them, so expanding across an apiary costs far less than a unit per hive. Each extra hive needs a Bottom Box Frame, from $49.96. One controller pairs up to 50 wireless sensors. Plan three units per standard household circuit.

Here is the full cycle, hive to hive:

1. Swap the insert. Pull the blank insert out of the bottom frame and slide the heater insert in. They are held magnetically, so it is one out, one in.
2. Open the top. Remove the telescoping cover and the inner cover. The inner cover stays off for the treatment.
3. Place your sensors, if they are not already in the hive, in the brood boxes wherever you want them, with the anchor sensor (the one with the hex anchor attached) in the center of the bottom-most brood box.
4. Set the ThermaHive top box on the hive, then put the telescoping cover back on over it.
5. Plug in. Connect the top box to the heater insert, then plug the cord into your power supply: wall outlet, solar battery, generator, whatever you are running.
6. Follow the prompts on the screen to set up and start the treatment.
7. Go live your life. Forget about the treatment until you remember a few hours later.
8. Break it down. Come back, remove the top box and the heater insert, put the blank insert back in, and replace your inner cover and telescoping cover.
9. Repeat to set up the next hive.

Once your sensors are placed, the top box remembers them against each hive ID, so hive two onward is mostly just moving hardware and confirming a screen.

Not as it is today. ThermaHive could work on top bar, Warre or long hives with some modifications, but we do not currently make a model that fits these hive types.

For the hives it does fit, see Will ThermaHive fit other hive types?

Rain or shine is fine. ThermaHive does not need any particular weather to treat.

The one limit is temperature. We do not recommend treating when it is below 50°F (10°C) outside unless you tape shut every opening and entrance first.

Below 50°F (10°C) it is too cold for bees to fly, and they start to form their winter cluster. Treating with the hive open can break that cluster and send bees outside to beard, where they can freeze to death.

Yes. You can run a treatment at any time of day.

Top Box with ThermaHive Controller, bottom treatment frame, heater insert with magnetic lock, blank insert, two SHT31-DIS wireless sensors, two hex saddle frame mounts, diffuser board, 8 GB micro SD card and power cord.

A 500 W self-regulating PTC ceramic element warms air at the base. A diffuser board spreads that air across the footprint instead of letting it rise in a column. Two 120 mm fans, one on each side, pull it upward and adjust speed to even out temperature across the box.

Even distribution is the hard engineering problem in thermal treatment, and it is most of what we spent 2026 solving.

A wireless sensor placed at bee space inside the brood nest, reporting every 2 seconds. One sensor is designated the anchor and holds the treatment setpoint; the rest monitor and log.

The controller regulates to the temperature where the bees and mites actually are, not the air at the edge of the box.

Yes. The sensors are designed to be placed once and left there.

Your top box saves each sensor placement against each hive ID, so once you have placed them, you do not need to change anything on the controller after the initial setup.

We do recommend pulling them periodically, during a hive inspection is the natural time, to clean off the bottom of the casing and make sure the bees have not propolized the holes at the base or blocked them up with wax.

Between frames in standard bee space, 6 to 9 mm. No drilling and no woodware changes. The included Hex Saddle sits across the top bars of two adjacent frames to hold it in place.

No. The sensors are sold on their own and work with BroodMinder products, so you can use them to monitor hive temperature and humidity without owning a ThermaHive system. See the wireless sensors.

Yes, after a firmware update. They also work with every V2 unit.

The enclosure is IP65 equivalent, so it handles rain and outdoor apiary conditions. Units in our field program stayed mounted continuously through storms and a Maryland summer.

620 Wh per treatment cycle, averaging 178 W with a 657 W peak, on a standard 110 V outlet. Three units maximum per household circuit. More than that needs a second circuit.

Those are measured figures from our own field program, not a nameplate rating.

Yes. We publish a full build guide for a solar battery setup for under $300 in parts: a 100 Ah LiFePO4 battery, a 1000 W inverter and a small panel with an MPPT controller.

That runs roughly one and a half treatments per charge, or about 47 days of passive monitoring.

No. Treatments run standalone and every session logs to the SD card. Wi-Fi is used at startup for setup and firmware updates, which is how our own control performance improved substantially mid-season through firmware revision without a single field unit being touched.

Live in-hive monitoring runs over the wireless sensors, with BroodMinder app integration for viewing data.

Full temperature and humidity logs for every session at high resolution, on the SD card and through the BroodMinder app. The log includes temperature, humidity, phase, mode, settings and safety events, all timestamped, and opens in Excel or Google Sheets.

You can show exactly what your colony experienced, which is not something any chemical treatment gives you.

Yes. V2 integrates with the BroodMinder hub and app, so treatment history sits alongside your existing colony monitoring in one view.

Yes, and most owners will use it more often for this than for treating. Winter monitoring logs hive temperature and humidity so you know a colony is alive without opening it. Spring warming supports weak colonies through cold snaps.

Winter use and warming have not yet been tested. Our 2026 field season ran April to September, so those modes are what the hardware is designed to do rather than something we have logged results for.

The unit carries a lifetime warranty and is designed to be field maintainable, with a modular layout so a part can be replaced without returning the whole system. Full terms are on the Lifetime Warranty page.

If something breaks, email us at support@thermahive.net with your order details and a description of the problem, and we will sort out the replacement part or repair from there.

Around 248 days, roughly 8 months, on a single CR2032 coin cell. That covers a full April to September season with time to spare. When it runs down, swap in any standard CR2032, sold at most hardware and grocery stores.

Not really. While the heater is running it sounds like a fan, and the heater does not run for the whole treatment.

It is a one-time purchase against a recurring cost, and the comparison improves every year you own it and every hive you expand to, since only the bottom frame is per hive. ThermaHive is covered by a lifetime warranty; chemical treatments are repurchased multiple times a year, every year.

It also removes costs that do not show up on a treatment receipt: resistance that makes your miticide stop working, residue accumulating in comb you will eventually replace, and colonies lost when a treatment fails.

Most heat devices make you remove capped brood frames and heat them in a separate box, which is hours of labor per hive. Passive solar hives need sun and the right hive orientation. Heat pouches have no power, no monitoring and no data.

ThermaHive treats in place, in a closed hive, on your schedule, and logs every session. It is also the only one we know of with a published field season of paired mite washes. See the full heat-device comparison.

They are not required, but we recommend some form of mite count. Whichever method you prefer, it is how you know where a colony stands, and without monitoring any treatment plan is guesswork.

The difference with ThermaHive is what the count tells you: whether a treatment worked, rather than whether the chemical still works on your mites.

Yes. You can use ThermaHive alongside chemical treatments.

Within 4 to 6 weeks of purchase, or free pickup at NAHBE 2027. Order Now.

V1 was a small batch of 20 working prototypes, not a production run. Seven of them ran the whole 2026 field season at our research apiary, and everything we learned from them went into the V2 design. The batch is sold out, and V1 will not be made again.

Yes. V1 units in the field are still supported and still receive firmware updates. V2 is a redesign, not a replacement of our obligation to V1 owners.

The new wireless sensors work with V1 after a firmware update, so you can add them to the unit you already own.

For a side-by-side of what changed between the two generations, download ThermaHive V1 vs V2: What’s Changed (PDF).

Return a brand-new unit for any reason within 30 days of delivery. After that, we refund units that are faulty, and our Lifetime Warranty covers repairs for as long as you own your unit.

Full terms are on the Return and Refund Policy and Lifetime Warranty pages.

No. The V1 tester program is closed, and there will not be one for V2. The 2026 field season, our research apiary and the independent testers who ran V1 units gave us the data we needed, and V2 is available to order now.

Yes. We offer international versions of the V2 Complete Kit and the Heater Insert with a 230 V heater, for countries on 220 to 240 V power.

They are built to order. You pay a deposit of 50% of the product price, plus shipping in full, when you order, and the balance when your unit is ready to ship. Full terms are in our Return and Refund Policy.