How Does Thermacell Work?

Thermacell devices use heat to vaporize a chemical repellent, which is supposed to keep mosquitoes away. The active ingredient is allethrin, which is a synthetic version of a naturally occurring compound found in chrysanthemum flowers.

Thermacell’s devices come in various shapes and sizes. Some are battery-powered and others use butane, which is a fuel commonly used for backpacking stoves.


Mosquitoes are a major threat to outdoor activities and events, especially during the summer. They carry diseases like encephalitis, West Nile virus, and Chikungunya fever, which can lead to serious illness and even death.

Thankfully, there are plenty of mosquito-repellent products that can help you enjoy your time outside without worrying about the bites. One of my favorites is a product called Thermacell, which uses heat and inexpensive repellent to create a 15-foot zone that bugs can’t touch.

The device works by using a controlled butane cartridge to heat a small metal grill that contains a blue mat saturated with repellent. As the mat is heated, it vaporizes the repellent and rises into the air to form a protective zone.

You activate the device by twisting a “on” slider and turning it on, a little way until you hear a click. The butane is then released and a tiny controlled fire begins to form beneath the heating element that the mat sits on.

Once the butane has ignited, it slowly heats up the blue mat, which is saturated with allethrin (a synthetic version of the natural insecticide found in chrysanthemum flowers). As it heats, the repellent disperses into the air, creating a bug-free zone.

After a few minutes, the entire area around the blue mat will be protected from mosquitoes, black flies, no-see-ums, and other biting insects. The repellent smells, but it’s not a strong odor and most people won’t even notice it.

A single mat lasts for about four hours, which is enough to protect your family or group of friends from mosquitoes. You can replace the repellent mat as needed, which is easy to do with the device’s simple design.


Thermacell is an innovative device that heats a repellent pad filled with allethrin to evaporate it into the air, creating an area of protection around you. This works well in areas of high mosquito populations, but it can also be used indoors on windows, doorways, and cracks to drive away biting insects as needed.

The product is odor-free, and it doesn’t require reapplication like most bug sprays. However, it is not as effective as a DEET or permethrin-based repellent.

In addition, small wind currents can disrupt the potency of the allethrin in the air and make it less effective against some mosquitoes. It does not offer long-lasting protection in heavy mosquito-infested areas, so you’ll need to reapply it at least once or twice a day if you are spending time outdoors.

It is a synthetic pyrethroid derived from a natural component of the chrysanthemum flower. It has low toxicity to humans and birds and is effective as an insecticide and repellent.

Chemicals in the pyrethroid family can be toxic to fish and aquatic invertebrates, so it is important to use caution when using thermacell on or near water. The chemical is especially toxic to trout and other salmon-like species, so it’s best to avoid ponds, lakes and rivers when using the product.

When it is used as a fuel-powered insect repellent, the Thermacell Device releases vapor containing a mixture of metofluthrin and allethrin (the Radius uses metofluthrin, the others use allethrin). The vapors excite neuroreceptors in the insects’ eyes, causing them to get “stoned” and lose interest in feeding on you.

The vapors also irritate the insects’ skin, which can cause itching or swelling of the affected area. This can be particularly uncomfortable for people with eczema or psoriasis, which are more likely to develop in response to the vapors.


Thermacell works by vaporizing a liquid repellent in a swappable cartridge that’s activated when the device is on. The repellent is then diffused into the air, which keeps mosquitoes from attempting to bite humans inside that protected zone.

In addition to keeping bugs away, thermacell also protects you from stings from bees and wasps. That’s because they’re sensitive to the chemicals in thermacell’s liquid repellent.

It’s easy to see why people who live in areas where mosquitoes are a problem have come to rely on thermacell. While some people still rely on those dreaded citronella candles, the majority of people are using Thermacell to keep mosquitoes out of their outdoor living spaces.

You can get your hands on a Thermacell in a number of different styles. Some use butane fuel cartridges that you’ll need to replace after 12 hours of operation, while others use a rechargeable battery and refill cartridges containing repellent pods that last for up to 40 hours.

Both options have a similar design: a small viewport where you can see when the flame is on and a power button that turns on a butane cartridge. To change the fuel, you simply unscrew the old one and screw in the new one. It’s a simple process, but it’s important to make sure you’re not replacing an empty cartridge.

If you’re traveling and want a more portable option, the brand’s newest model — the Radius — uses a battery instead of butane cartridges. It’s compact enough to fit in a bag or suitcase and can be used at altitudes that fuel-powered devices can’t.


Nothing spoils an outdoor meal or party like a swarm of mosquitoes, and they can spread serious diseases like the Zika virus, West Nile virus, encephalitis, and Chikungunya fever. But a new Wi-Fi-connected Thermacell system called Liv offers a way to keep these insects at bay without exposing yourself to nasty chemicals or messy bug sprays.

Liv uses physical repellers, a smart hub, and an app to control the system and monitor its performance. The repellers use Thermacell’s 5.5 percent metofluthrin-based repellent formula, and each repeller can be connected to up to five others for maximum coverage.

The Liv starter kit starts at $699 for the hub, three repellers, cables, standard mounts, and ground stakes. It can be added to with additional repellers for $150 per extra unit, though you’ll need to order a new hub if you add more than three units.

Each repeller can be placed on a wall, tree, or other surface to create a repellent zone of up to 110 square feet. You can connect the repellers to a home Wi-Fi network, and you can control them using an app on your smartphone or tablet.

You can also connect multiple units to one hub for a single outdoor area, and the smart hub can be programmed to automatically run the units when it detects mosquitoes in that space. The app can also be used to schedule operations at specific times of day, as well as to report the level of repellent in each zone.

Leave a Comment