Product test

Thermacell: a mosquito repellent that can’t quite perform miracles

19.8.2021

Thermacell is said to work wonders in the fight against mosquitoes. The evaporator is supposed to form a protective bubble shielding you from the pests outside. Will it work? I’ve tested it.

The summer of 2021 is a very special one. Quite a few areas have already experienced more than the average amount of rainy days, SRF Meteo reported (website in German). Humid summers are perfect conditions for a mosquito plague, as the NZZ writes (website in German). An insect expert speaking to the portal «Argovia Today» (website in German) finds the fine buzz of mosquitoes in the air gratifying because many insects in the air also mean a richer food supply for birds and fish.

But that’s enough of the pros and cons. From here on, it’s all about the fight against mosquitoes. There are many remedies against them, as you will learn in this post:

Guide
7 remedies that protect against mosquitoes – and one that’s of no use
by Martin Jungfer

How Thermacell works

The Thermacell I’m testing is an evaporator. When heated, it releases vapours containing the active ingredient against mosquitoes. Thermacell relies on D-allethrin, a pesticide with a knock-down effect. What does this mean? Mosquitoes that come into contact with the vapour are paralysed by the neurotoxin and eventually suffocate. Of course, this isn’t stated on the packaging or in the instructions for the Thermacell that explicitly. The two warning signs on the active ingredient plates are nevertheless clear: with 22 per cent of the active ingredient, the stuff is «toxic» according to the fine print if you swallow it and is considered «harmful» if you inhale it in large quantities. It’s «very toxic» to aquatic organisms.

Lots of warnings – Thermacell vaporises an insecticide.

Using Thermacell

I received three current models for testing. All of them work with the same principle. They’re fuelled by a butane gas cartridge that holds just under twelve millilitres and is about the size of a hotel shampoo bottle. This gets placed into a screw thread, thereby opened and starts the gas supply. By turning the device on, the process begins and a small metal plate in the device is heated. Above this metal plate is a grid construction made of hard plastic, under which you slide the active ingredient plate.

The gas cartridge is screwed into the bottom.

According to the instructions, the small gas cartridge lasts for twelve hours. An estimation that proved to be realistic in the practical test. One active ingredient plate evaporates after about four hours and must then be replaced. If you don’t have an eye on the time, you’ll see that it’s time for a change when the tile is no longer blue, but white. Replacement cartridges and plates are available in various portion sizes and combinations. For simplicity, the duration of protection provided by a refill kit is always indicated.

Animal repellers

Thermacell Mosquito repellent

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Thermacell Camping Backpacker MR-BP

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Thermacell MR300 Portable Mosquito Repeller

Animal repellers

Thermacell Refill set mosquito repellent

Animal repellers

Thermacell Refill set

You can switch on Thermacell via a kind of Zippo mechanism. Flip a switch up or turn the stand, which creates a spark and ignites the gas. There is a separate off switch on another device. On the floor unit, simply turn to the «off» position.

When you’re ready to use the device, it takes about 15 minutes for the metal plate to heat the active ingredient to the point where the vapour has been released in sufficient quantity. After the warm-up phase, an area of four and a half by four and a half metres should then be free of mosquitoes – if there is no wind. After all, 20 square metres should be enough for almost any balcony and most seating areas.

It gets trickier with wind: then you have to position the device so that the vapours are blown to where you’re sitting.

How well does it work?

I tested the Thermacell in two places. One is in Switzerland at Lake Greifen, which is particularly infested with mosquitoes this year. The other was at a wooded campground in Italy that, based on a previous visit, qualified as a testing ground with particularly biting mosquitoes.

In Italy, the «Halo Mini», as the Thermacell is called in its stand-up form, was present on restaurant terraces and was allowed to wrap its protective cloud around us parents while the offspring made their first dance attempts at the open-air kids’ disco. For the test, I even did without the usually used Autan based essential oil. Instead, the Thermacell was on the floor between my feet. After all, the number of mosquito bites the next morning was only in single digits. That could’ve ended worse.

The Thermacell has to prove itself in this Italian garden restaurant. It won’t pass for a table centrepiece, but again, it’s not particularly ugly.

The effect was better in the restaurant – at least for me. Female members of the family were still stung sporadically despite Thermacell and Autan. This prompted my six-year-old to say, «Dad, this isn’t working!»

Back home in Switzerland, the Thermacell performed better at a barbecue with colleagues in the garden. Here, all participants came away unstung.

Verdict

The Thermacell did a decent job in my test, but doesn’t perform miracles. They tell about such miracles in Internet videos – to me, these are a lot of euphemisms of YouTubers, who are possibly paid for positive reviews. According to my observations, mosquitoes do reach the protection zone once in a while. Some of them were able to eat a last supper before they died.

The use is simple and straightforward. If you don’t want to spray or oil your skin, you’re sure to enjoy the Thermacell. Once turned on, you don’t have to change the active ingredient plate until after four hours. Sprays and oils also work for about this long.

Speaking of switching on: you can tell if your Thermacell is running when you see an orange glow in a small peephole. This is easy to see at dusk and in the dark. A bit more difficult during the day when the sun is shining.

You can tell you’re doing it right when the light comes on.

Thermacell has two disadvantages:

You vaporise a highly effective but also toxic pesticide, of which you also always inhale a little. Of course, everything is tested for safety; otherwise it wouldn’t be sold. But an uneasy feeling still remains, at least for me.
The protection isn’t cheap. Thermacell has set up a Nespresso-like business model. The device is available at a low price, and they earn money with the required plates and gas cartridges. Depending on the refill kit, you’ll pay around 80 Rappen for gas and active ingredient for one hour of insect protection.

Despite the disadvantages, I will keep the Thermacell and also treat myself to a refill set again. Perhaps Ms Daughter will also give the device another chance.

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Martin Jungfer

Head of Content

Martin.Jungfer@digitecgalaxus.ch

Journalist since 1997. Stopovers in Franconia (or the Franken region), Lake Constance, Obwalden, Nidwalden and Zurich. Father since 2014. Expert in editorial organisation and motivation. Focus on sustainability, home office tools, beautiful things for the home, creative toys and sports equipment.

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