Fight the bugs

Craig Grosby


Thermacell Mosquito Repellent Outdoor Lantern (Model MR-9L)

MSRP $31.99
  • Portable
  • Easy to use
  • Safe for outdoor use
  • Long-lasting
  • Not recommended for windy conditions

Have you ever sat in the cockpit at dusk after a long day of sailing, only to find yourself being eaten alive by mosquitoes? Tired of having to retreat to the cabin and hide behind screens? Thermacell has the perfect solution with its Mosquito Repellent Outdoor Lantern.

The lantern can be operated separately and is pretty straightforward to use. It has eight LEDs powered by four AA batteries. An opaque, four-sided lens provides good light for up to 200 hours on the low setting and 50 hours on high. When using the unit just as a lantern, you can hang it from a Bimini using the small handle on top. When used as a mosquito repellent, however, it should be placed on a flat, stable surface.

The unique mosquito repellent system uses a small plastic butane cartridge and insect repellent mats about the size of adhesive bandages. The mats are inserted into the top of the unit, and the butane cartridge goes into the base. The butane cartridge is good for 12 hours, and individual mats last for up to four hours. Refills are readily available.

The butane cartridge warms the mat, which emits a nearly invisible vapor to repel the mosquitoes. The active ingredient is allethrin, a synthetic form of pyrethrin, a naturally occurring repellent. Allethrin is commonly used in mosquito coils. (As allethrin is toxic to fish and other marine animals, it is recommended you contact your state water board or regional Environmental Protection Agency office to learn about proper disposal of the used mats.)

Following the operating instructions on the package is pretty simple as well. I particularly like the small viewing port that glows orange to let you know the unit is repelling mosquitoes.

How well does it work? The instructions say that it will repel flying insects for up to a 15-by-15-foot area. You need to allow 10 to 15 minutes, depending on the size of the area, for the product to take effect. I used the unit several times at dusk, when mosquitoes and gnats are the hungriest.

I get bit at the first sign of mosquitoes. I had high hopes for this unit, and it did a marvelous job. I sat outside for hours at a time with nary a bug bite.

One area of concern was that the unit is not for use in windy conditions. So how was it going to perform on a boat at anchor? Simple—when it’s windy, there are few mosquitoes. It’s usually on still nights that the bugs come out.

My other concern was carrying the flammable butane cartridge, but the butane cartridge is no different than a lighter, which I would consider safe to carry on board. Having said that, I would not leave it in the engine room or where it could be exposed to extreme temperatures.

Overall, the portable lantern is effective, silent, easy to operate and safe to use outdoors.

Craig Grosby, P, an avid sailor, has been a USPS member for more than 25 years. He currently hails from Fort Lauderdale, Fla., and frequents the Florida Keys aboard Flyer, a Hunter 35.5 Legend.

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