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Throughout long summer weekends until days get short, backyards and block parties fill up as family and friends come by, convene, congregate. But they also fill with unwanted visitors … hundreds, even thousands of them. Mosquitoes. Thermacell Repellents, Inc. wants to keep mosquitoes away from you consistently. To do that, company entomologists surround themselves with mosquitoes constantly. And, for a few hours, so did I. 

In and around the Thermacell Science & Research Center, lab work and field testing are driving product innovation for spatial mosquito repellents. Using a heat source to vaporize chemicals into the air, these products are built around an invisible zone of protection rather than sprays, smoke, or scent … or some combination of coils and oils. But Thermacell’s toughest competition isn’t candles and canisters or concept drones performing air-to-air kills. Thermacell’s real “rival product” is the back door. It’s when people get fed up of being fed on and simply head indoors. 

“Our biggest competition is inside, because that’s the only thing that works 100%,” says Adam Goess, Executive Director, Global Insights & Innovation at Thermacell. “We want to protect outdoor time from being interrupted, get people back out there.”

And learning how they do that is why I traveled to tour a converted building in Hampton, Fla., about 25 minutes northeast of Gainesville.

See It

“I don’t know if you noticed driving up, but the building looks a little churchy, because it was a church … inside you can see the area where the pews were, and the baptismal pool was,” explains Dr. Rebecca Heinig, my primary guide and senior scientist for the entomology programs at Thermacell.

There’s no steeple or religious signage, but once pointed out, the gabled design becomes obvious. And it’s appropriate that the facility, opened by the Bedford, Mass.-based company in 2024, is a former house of worship, because invisible repellents ask for a kind of belief. You turn one on, see nothing, smell nothing, hear almost nothing … and trust that the mosquitoes are experiencing a zone that’s discernibly different. Inside, Thermacell is justifying that trust with quantifiable science.

When most companies talk about inventory, their parts may have teeth or tongues, but here the stock actually bites. So each door is a trust exercise that I won’t become a feast for the world’s deadliest animal on the other side. We enter the insectary, behind an air curtain meant to keep mosquitoes from escaping. But why would they even want to?

Within immaculate white, very Lumon Industries walls reverberating with a restless drone is an environment optimized for these insect antagonists. Warm and humid, a toasty 80 degrees Fahrenheit with 70% humidity [aka “morning,” if you grew up in the Deep South like I did], this room creates a synthetic swamp where picky larvae get clean water, their eggs are carefully stored, and, when needed, fully grown mosquitoes get defibrinated animal blood delivered through heated membrane feeders.

On one side of the room, plastic tubs are full of tiny eggs, like cracked pepper waiting to make lawns zesty. On the other side, it’s unnerving to see hundreds of quivering proboscises, the tube-like mouthpart mosquitoes use to pierce our skin and gorge on our gore, poking through the mesh of colony cages as they sense an edible epidermis get near. But I am promised no interns have to offer up an appendage to science. “There are places [testing topical repellents] where you stick your arm in the cage; we don’t do that here,” says Dr. Heinig.

The premise is simple. The opponent is not. Breed, identify, and test, because different mosquitoes carry different implications. They are disease vectors, explains Dr. Heinig, where the stakes of battling the species that matter the most are larger than avoiding an itch. These insects have been sucking human blood for more than 1.8 million years, bringing with them dangerous, even debilitating diseases annually. Malaria, West Nile, EEE, dengue, chikungunya, Zika. Parasites and viruses that cause issues far beyond the discomfort of a whine in your ear and a welt on your ankle.

Complicating matters, mosquitoes can learn, adapt, and combine cues from smell, heat, and vision; one recent study even found that mosquitoes could develop an almost Pavlovian response to commercial insect repellent diethyltoluamide (DEET) and associate it with food under certain conditions. That’s just one of many factors that might make you smell delicious to them. That doesn’t make DEET useless, but it makes it clear that mosquitoes are something far more sophisticated than just tiny syringes with wings. They’re responding to prompts we don’t know exist, which is why repellency feels like an ongoing behavioral argument that has to be readdressed every year as environmental cues trigger the mosquito life cycle.

I ask whether one reason for the facility’s subtropical location is that it’s easy to harvest eggs from the neighboring swamps. It turns out proximity to Florida sites helped inform the Thermacell center’s founding, though the surrounding wetlands are only part of the picture. The Mosquito and Fly Research Unit at USDA Center for Medical, Agricultural and Veterinary Entomology (CMAVE), just a 40-minute drive from Thermacell, provided the original mosquito eggs and is an appreciative partner because good pest control starts with knowing the animal.

The goal isn’t simply to have mosquitoes; it’s to have the right mosquitoes in the right numbers. It’s to ensure the right species, particularly Aedes albopictus, the daytime-active Asian tiger mosquito, are represented. Sometimes it’s to have genetically modified mosquitoes that glow under ultraviolet light, their fluorescent marker proteins making them easier to track. It’s also to ensure no undesired diseases accompany them [there’s always going to be an escapee or two]. 

And rearing mosquitoes requires more than just getting eggs wet. So Thermacell recreates one of nature’s signals that tells dormant eggs it’s time to hatch: falling oxygen levels. In the wild, this happens after, say, rain, as decaying matter in fresh stagnant water fuels microbial respiration. This, in turn, tells embryos to start their 24- to 48-hour transformation into wigglers. Thermacell recreates that signal but, apologies to Elton John and Disney et al, no one in here is waiting for the circle of life to move us all. 

In another lab, I’m shown how pressure is manufactured and hatching a batch is accelerated to less than 30 minutes. These hallways aren’t long, but each room advances both mosquito and product development another step. “It helps the insectary keep our timeframe, so we don’t have first instars [a larval growth stage] with fourth instars with pupa, so that they all kind of stay in line in their developmental stages,” explains Gina Barella, a biologist and entomology enthusiast at Thermacell.

Synchronized emergence is imperative to have enough subjects to compare products under controlled conditions, and predictability is one of the facility’s biggest scientific advantages. “We don’t want to have one apple at a time; we want to have them all ripen at the same time, so we can do everything at the same time,” says Dr. Heinig. “We want the same thing, but with mosquitoes.”

“We’re targeting being able to rear about 40,000 mosquitoes per week to accommodate our testing needs.”

Scale is one of the Hampton facility’s core innovations. Forty thousand mosquitoes sounds like quite the infestation until you learn that only half, the females, feed on blood. Those are the only ones the lab needs, which is why rearing the mosquitoes is just the beginning of the job, not the end of the story. Collecting the right sex at the right age to keep tests standardized is a very painstaking, hands-on craft. It also used to be a very lungs-on one.

You can’t just vacuum up the mosquitoes indiscriminately or without injuring them. An aspirator gently transfers selected insects from one environment to another via controlled suction so researchers can separate, sort, and cage them for testing. Thermacell now has a pump- and pedal-operated setup, but that wasn’t always the case. Previously, technicians powered the vacuum themselves.

“We invested in this beautiful, automatic aspirator, but before that it was all mouth aspirators,” says Trinity Shirk, a science technician at Thermacell. “After a while, you would get a little lightheaded.” 

A motor’s steady whirr broken up by the sound of rushing air, Shirk shows me how both the old and new aspirators let her capture her tiny targets, one hand on the tube and the other on her tally counter. These mosquitoes are compared against reference specimens from different angles to ensure the sample set. Only after this sorting can the mosquitoes graduate to increasingly realistic experiments that test concoctions cultivated in separate tightly controlled quarters where expanded collaboration compresses development cycles. 

“Our chemistry department was located up in Georgia, because we have a distribution center there, but in 2024 we decided it would be a really good idea if we could put chemistry and entomology in the same building together,” says Dr. Heinig. “So on Monday they can say, ‘Well, we’ve got something interesting,’ and entomology can say, ‘Well, I think we can test that tomorrow morning.’ 

“And within a day or two we can tell formulation what’s looking good, or what we can tweak a little bit. That used to take a couple weeks, when the chemists in Georgia would send something down to Florida, and we’d have to wait for the weather to cooperate.”

Under hoods, release rates are tested. In a side room, gas chromatography spectrometers and flame ionization detectors offer visual representation of chemical fingerprints. Once a set of ingredients is ready to be tested and a sample set of insects is assembled, the two can meet each other. This is where Florida truly transitions from Thermacell’s address to part of its apparatus.

Bugs sense things that people can’t, like our octenol, lactic acid, carboxylic acids, ammonia, and carbon dioxide. Out in the semi-field trial screenhouses, a fan-powered BG-Sentinel mosquito trap acts as a surrogate human. It emits artificial skin scents, and 1,000 of those carefully sorted females, give or take, are lured into zones that have just a trap or a trap with a Thermacell device. The number recaptured during a specific period is the repellency estimate. What’s key is to see how the latest formulation performs in these permeable flight cages, under the sun, wind, humidity, and temperature conditions where sweaty socks and skeeters would actually meet.

Then there are regulatory-style field studies where reactions of the lab-grown mosquitoes are compared against naturally occurring populations of Culex, Aedes, Anopheles … 20-30 of the most common species in season [for perspective, there are about 200 species in the US, and about 3,700 worldwide]. Behavior in the barns provides data that truly helps refine the chemistry and delivery of Thermacell’s products. Using an actual backyard means Thermacell can confidently say, if your property is like this, the product works like this. 

As conducive as Florida’s weather is to Thermacell’s goals, even the elements take a few months off. That’s why where once there were pews in the building, there are now two modular, vinyl-lined, easily sanitized enclosures where temperature can be controlled. It may not be able to recreate every factor the way they interact outside, but it means all work doesn’t have to pause during the winter. [It’s also a perfect environment to test Thermacell’s no-spray, no-mess, permethrin-infused cotton-stuffed Tick Control Tubes, because even better than knowing how to properly remove a tick is never having to remove a tick at all.]

Combining all of these environments is how the insectary’s inventory becomes evidence. This is why the facility is a huge advantage.

Gathering data, however, doesn’t get most people excited. Having a 20-foot diameter of mosquito-free bliss, on the other hand, does. So the scale of testing at the Science & Research Center is systematically improving the scale of an entire product family. It’s expanding both the space Thermacell operates in and the number of people that can operate comfortably in the space its products create.

Thermacell began, as the name implies, with a system built around heat + power. “What’s known as a handheld is really where Thermacell got its start,” says Goess. 

These butane-powered mat-based products, particularly well-known to hunters, anglers, and campers, were foundational because they were quiet, scentless, and didn’t damage equipment the way chemical sprays could. Introduced in 1999, they were quickly a must-have accessory for outdoor enthusiasts. With no open flames, safe enough to be used in a mine without fear of explosion, handhelds were family-friendly but still seen as field gear for activity-oriented sportsmen. The Patio Shield, on the other hand, “really opened up the door to the backyard,” says Goess. 

The Patio Shield was Thermacell’s first product to sell a million units, helping the company penetrate a much broader base: people relaxing. The initial Patio Shield still required two consumables, however: a four-hour mat and a 12-hour cartridge. A common frustration was that people would often run out of one and not the other. The key unlock was a rechargeable product, initially introduced as a Kickstarter in 2018.

“We launched it in a very Thermacell way, almost as a proof-of-concept,” says Goess. “It really showed the spirit of Thermacell, because being a disruptor means we can’t be afraid to disrupt ourselves to provide a better consumer experience or solve consumer pain points.”

The E-ZoneGuard Patio’s intuitive shape, much like a stemless wine glass, signals that it goes on the table between people. Consumer feedback helped inform visual and audible cues in subsequent products, so you could know it’s working without demanding attention. “We want to be at your party … but we don’t want to be the center of attention,” says Goess.

The ultimate proof, however, was when the mosquito pressure goes away. And with that no longer questioned, consumers started commenting on battery life, so Thermacell turned its attention to better cells and charging base upgrades. Driving habit-forming usage even further was the introduction of a model with a wireless dock, so the product didn’t “die by counter,” shoved under the kitchen sink and forgotten when it turned out not to be charged. Each generation of Patio reduced the need to interact with the product without reducing its efficiency. This proved valuable because, while the protected zone from a single product may not have grown, the social setting for Thermacell has.

The culmination of this hands-off bug(s) off approach is the LIV on-demand system, originally introduced as a DIY system in 2022 and upgraded in 2026 to a professionally, permanently installed 2.0 iteration that’s earned one of our Home of the Future awards. An app-enabled IoT array of a 110V AC smart hub powering up to 10 aluminum repellers via low-voltage wiring, a LIV 2.0 system is intended to remove the friction of recharging and retreatment. Wi-Fi connected, able to be activated, scheduled, and monitored remotely, with refill levels/alerts delivered to your smartphone, the LIV system allows you to start your bubble of protection before activities, not reactively.

The four-season durability and 3,000 square feet of maximum EPA-registered protection against mosquitoes and no-see-ums (biting midges, aka Culicoides) is intended for big properties and commercial venues, where hospitality without harassment can create “the good kind of buzz.” [I wish I could say I wrote that one, but Thermacell got there first.] 

I learned how the LIV system works standing behind Thermacell’s facility. I see how the LIV system works later in the evening on the back patio of the Swamp Head Brewery, a taproom in an industrial park on a small lagoon, complete with alligator … and unassuming die-cast cylinders of protection attached to the patio’s railing. I was acutely aware that I started the day surrounded by bugs, but now I’m acutely aware that I don’t notice any insects. No one is swatting at anything. It’s just beers and brats. And that ability to enjoy uninterrupted is the true measurement of the Science & Research Center and Thermacell’s success.

 

2026 Popular Science Home of the Future Awards

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