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This is how I'm keeping myself mosquito-free this summer

I live in Maine. This is how I eat dinner outside without getting devoured.

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The bugs are so bad. 

I live in Maine. If you've spent any time here, then there is no further need for me to establish any bonafides about the volume and belligerence of our insect population. But this year's interminable winter and rainy, frigid spring produced ideal conditions for this state's legions of black flies, ticks and mosquitoes. "It's a pretty heavy infestation," says Griffin Dill, an Integrated Pest Management Professional at the University of Maine. 

Read more: How to repel mosquitoes this summer

Of course, he just confirmed what I already knew: The bugs are so, so freaking bad. But, this year, I resolved to fight back. My goal: eat dinner outside with my family. And I am pleased to report that I have found an affordable solution that has helped me achieve this goal frequently throughout the summer. 

Massachusetts-based Thermacell makes a line of devices designed to keep mosquitoes in check. I tested the Radius ($40 at Amazon), the Patio Shield ($20 at Amazon) and the MR300 ($25 at Amazon). Though the Amazon reviews are decidedly mixed, the three I tested worked well, and were more or less equally effective. 


Thermacell's Patio Shield.

Justin Jaffe/CNET

Though they're all slightly different, they each ultimately do the same thing: Release a vapor containing a synthetic version of a chemical found in the chrysanthemum flower. (The Radius uses metofluthrin; the other models use allethrin.) According to Dill, the bug expert, these compounds excite insects' neuroreceptors, which dissuades them from feeding. In other words, the mosquitos get stoned and lose interest in biting you.

A few caveats about some potential risks. Amazon includes a Proposition 65 warning for California residents that discloses that Thermacell's repellent contains chemicals known to cause cancer and birth defects. Allethrin and metofluthrin are also toxic to some animals including birds, fish, bees and cats. Dill said that "though the potential for harm to humans is there, it's probably low," but he cautioned to use these devices in moderation and never indoors.

Thermacell says its devices create a 110-square foot or 15-foot zone of protection, depending on the model. I found that each of them was effective in creating a small but real opium den for mosquitos around my backyard table, which seats eight people. When we used the devices, we got far fewer bites. (The flies were as attentive as ever, sadly.) 


Thermacell's Radius model.

Justin Jaffe/CNET

Though he hadn't tried the Thermacell devices, Dill said that he had heard good things about them from colleagues. And he steered me away from a few other popular products: 

  • Those mosquito-repellent bracelets that look like old-fashioned telephone cords: They don't work. 
  • Citronella candles: Those don't work. 
  • Those organic essential oils favored by hippies like my wife: Dill wasn't willing to say they don't work, but he did point to the dearth of research about their efficacy and safety.

But, in my experience, over several weeks, earlier this summer, the Thermacell products work. Admittedly, my primary testing ground -- a fenced-in backyard that runs about 30 feet by 30 feet -- may present optimal conditions for these devices. I found the MR300 less effective when I walked with it, and areas with a significant breeze may see lower efficacy. (Again, you should never use these devices indoors.) And though the three models I tested were equally effective in mitigating mosquitoes, there are differences when it comes to price, form factor and fuel. I've examined them below.

Note CNET may get a share of revenue from the sale of the products featured on this page. 


The least expensive model in the lineup, the Patio Shield is roughly the size of a Thermos. It comes with one butane cartridge and three repellent mats, which the company says provides about 12 hours of protection. The cartridge that came with my unit lasted for about 11 hours, used over the course of several days, and the third mat appeared to have more repellent on it when the unit powered down. Thermacell's 72-hour replacement pack, which includes 18 repellent mats and 6 fuel cartridges, costs $30. The 48-hour pack costs $13.

Setup is simple: screw in the butane cartridge, insert the repellent mat and give the bottom of the device a twist. (Make sure you remove the lid during use.) My only complaint: the faint orange indicator light is difficult to see, and I wondered whether the device was on until I saw vapor coming off the repellent mat. 


The company bills this model as "portable," but they're all compact enough to move around a house or take on the road. The MR300 uses the same butane cartridges and repellent mats at the Patio Shield, but has a slightly different power switch. Thermacell also sells an armored version for $30; it's reinforced with rubber, comes with a belt clip and what looks like a better, more pronounced indicator light.


Based on the pictures online, I was expecting something bigger. But the Radius is a compact 3 x 2 x 3 inches. It looks like a small electric pencil sharpener with a hole on top. An illuminated power button makes it relatively easy to see whether it's on or off -- an advantage over the dim indicator lights on the Patio Shield and MR300, which I found hard to see in daylight.

The Radius costs about twice as much as other models because it's rechargeable (via an included USB cable), so you don't need to shell out for the specialized butane cartridges used with the Patio Shield or MR300. But the Radius has its own pricey consumable -- a repellent cartridge that costs around $8 for a 12 hour cartridge or $16 for the 40 hour version. (These repellent cartridges are not compatible with other Thermacell devices.) The Radius automatically turns off after two hours, which has definitely helped me conserve battery and repellent after I've wandered away from it after dinner. Note that this unit is less appropriate for camping or other environments where electricity sources are scarce. 

(Note that Amazon would not ship the Radius to my home in Maine, so I purchased it directly for $50 from Thermacell, which offers free shipping on orders of $49 or more.)

Editor's note: Since we started testing the Thermacell devices, we have identified some alternatives in the same price range including the OFF PowerPad Lamp and Lentek MM30C Bite Shield. We will be testing both of them, and will update this article with the results. 

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