When you are concerned with mosquito-borne illnesses like the West Nile virus present here in Texas, finding effective ways to repel mosquitoes in addition to the standard repellent sprays (containing DEET) is of great importance. The Thermacell Mosquito Repellent appliance is an outdoor device used to repel mosquitos within a 15′ x 15′ area. I found it to be an effective tool when repelling mosquitoes. This handheld appliance is also lightweight, portable and easy to use. Even though it will protect up to a 15′ x 15′ area, when using the Thermacell device, I was consistently within three feet of it so I did not personally observe whether or not it provides effective protection at greater distances. In addition to having the desire to avoid contracting the West Nile virus, I also have an M.S. degree in Entomology (study of insects) and thus I find insect related products fascinating. As a result, I volunteered to review the Thermacell Mosquito Repellent appliance.
The above were sent to me to review. The Thermacell Mosquito Repellent shown in the center of the above photo is the basic kit. The Thermacell Holster with Clip, the All-Purpose Swivel Light, and the Mosquito Repellent Refills are all accessories that must be purchased separately. Thermacell products may be purchased from places like Thermacell, sporting goods stores, Home Depot, Amazon, Target, etc.
Package Contents (appliance basic kit)
- Thermacell Mosquito Repellent appliance for outdoor use
- Three insect repellent mats (each lasts up to four hours)
- One butane cartridge (lasts up to 12 hours)
- User Guide
Design & Build Quality
The Thermacell Mosquito Repellent appliance is made almost entirely of hard plastic with the exception of the metal plate that is used to heat the repellent mat which volatilizes the insecticide. The front of the appliance contains an On/Off switch that releases or shuts off the butane. The small round button to the upper right of the On/Off switch is the Start button which ignites the butane that heats up the metal plate just beneath the plastic grate.
The back of the appliance displays the grips that accommodate your fingers while you carry it around during camping, fishing, hunting, geocaching, etc. The narrow vertical rectangular window just above the black cap allows you to see the amount of butane left in the cartridge (when the cartridge is in place).
The top of the device allows you to see whether or not the butane is lit (there will be a faint red glow), indicating that the appliance is on.
Included with the Thermacell Mosquito Repellent is a repellent kit that includes three repellent mats and a butane cartridge. The repellent mat slides into the appliance from the side. It is a tight fit so that the mat will not slip out when carrying the appliance.
A single repellent refill which contains three mats and one butane cartridge costs $6.99 from Thermacell (four refills cost $20.99, and 10 refills cost $54.99).
The mats are a solid blue color when unused and slowly become white as you use the device. When the mat is almost completely white you will need to replace it. To replace the mat, you simply slide another in through the opening on the side of the device, forcing the used one out through the other side.
After removing the black cap from the base of the appliance, you insert the Thermacell butane cartridge into the appliance and rotate clockwise to tighten the cartridge.
Once the cartridge is firmly in place, the black cap snaps easily back onto the appliance.
The holster comes in other colors and is an accessory that may be purchased separately for $12.99 from Thermacell. It is made of nylon and contains two side pouches to carry extra repellent mats and an extra butane cartridge.
The back of the holster contains a rotating clip that may be applied to any piece of clothing.
The side pockets of the holster have elastic openings that are tight enough to keep the refills inside the pouch and are easy enough to open when extracting a refill when needed.
The holster also has a window to allow you to see if the appliance is on.
If you choose to purchase the All-Purpose Swivel LED Light, it will cost $9.49 from Thermacell. The part to the right of the light in the above photo is a slide-on clip to attach the light to the brim of a ball cap.
The top of the appliance accommodates the All-Purpose Swivel Light which slides easily into position.
When the light has been fully inserted into the appliance, it fits flush with the plastic grate. The light is hinged and thus can be rotated forward or backward. The light also has two settings: White light and Green light.
Using the white light setting of the Swivel light proved to be quite bright.
The green light is less harsh.
Reason to use the Thermacell Mosquito Repellent
West Nile Virus: The West Nile virus is present here in Texas and is transmitted by mosquitoes (FYI, only female mosquitoes bite – they need at least one blood meal in order to develop their eggs). The virus is carried by over 60 mosquito species (according to the University of Illinois). Eighty percent of those who contract the virus will show no symptoms and those who do will exhibit flu-like symptoms (according to the World Health Organization) with fever, headache, tiredness, body aches, nausea, vomiting, occasionally a skin rash on the trunk of the body, and swollen lymph glands; a small fraction of those who show symptoms will develop West Nile neuroinvasive disease which is the life-threatening form. Anyone can contract this form of the virus, but those over 50 years old and those who are immune-compromised are most vulnerable. The symptoms of the West Nile neuroinvasive disease include headaches, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. It is estimated that approximately 1 in 150 persons infected with the West Nile virus will develop the more severe form of the disease (according to the WHO). Last year there were 379 human cases with 6 deaths in Texas (according to the Texas Department of State Health Services) – the counties affected centered solely around the DFW and Houston areas. Several communities around DFW sprayed for mosquitoes in 2014 to help stave off the threat since there is currently no human vaccine available. This year has not been an active year for West Nile but it varies from year to year and finding effective repellents is extremely important for those of us who reside in the parts of the U.S. that have West Nile.
The above map comes from the Center for Disease Control and may be clicked on to view a larger size. The incidence of West Nile present in each state is extremely low this year: each state that has had human infections, has had less than five cases so far.
To begin using the Thermacell Mosquito Repellent Appliance, you must rotate the switch to the On position, after which you can hear a very faint hissing sound of the butane being released. You’ll then wait about five seconds, then press the Start button about three times to ensure that you have lit the butane.
The above photo shows the faint red glow when the butane is lit and the appliance is on.
When using the appliance, I placed it on the lower shelf of an outdoor coffee table on our small patio which is about 10′ x 15′.
Thermacell Effectiveness: I used the device on average one hour per day for a total of just over 8 hours of use. Most of the time I was by myself but on a couple of occasions I was with others. Our experiences with the device were similar. None of us ever received more than three mosquito bites on any of the outings and several times I received no bites at all. We have a thriving mosquito population here in Texas and I believe that without the device we would have received many more mosquito bites. My observations also show that the repellency effect is not 100% so if you are concerned about contracting a potentially life-threatening illness that is transmitted by mosquitoes, you should use additional measures to protect yourself (getting rid of standing water, wearing clothing that covers your body, using DEET, or simply staying indoors during dawn or dusk when most mosquitoes are active).
Thermacell Effective Duration: The repellent mats are supposed to work for up to four hours and the butane cartridge up to 12 hours. I found that while using this device, my times were different than that suggested by the manual. I was able to use only two mats for one butane cartridge – that is, the butane cartridge lasted only about eight hours. But aside from this, I was pleased with the use and overall results of this product.
Thermacell Scientific Studies and Active Ingredient d-cis/trans allethrin: The repellent mats contain the active ingredient called d-cis/trans allethrin (21.97%). This is a synthetic insecticide in the group of insecticides called pyrethroids (insecticides generally ending in -thrin, but there are others like fenvalerate). Allethrin is included in the group of first generation pyrethroids which were developed from the natural insecticidal properties of pyrethrum in chrysanthemum flowers. This group of insecticides is frequently used in urban environments to control insect pests because they pose a minimal threat to mammals and birds. Studies have shown and support my observations that the Thermacell device containing d-cis/trans allethrin in the mats repel mosquitoes (Alten et al.1, Revay et al.4, Dame et al.3). These studies also show that the Thermacell mats will knockdown (insect paralysis just before death) and kill mosquitoes (Bibbs et al.2) and decrease bites from biting flies as well (Alten et al. 1). These studies were performed in Turkey (Alten et al.1), Israel (Revay et al.4), and the U.S. (Bibbs et al.2, Dame et al.3). There are relatively few studies testing the repellent, knockdown and mortality effects of products like the Thermacell Mosquito Repellent in the U.S., thus more studies are warranted.
General Information on Toxicity: Many consumers are concerned about using insecticides around adults, children, and pets. All pesticides and chemicals are given a DANGER, WARNING, or CAUTION label (or signal word) to indicate how dangerous or toxic the chemical is. To determine toxicity, the manufacturer performs testing of oral, inhalation, and dermal absorption exposure effects and also investigates irritation to skin and eyes. The route with highest toxicity according to LD50 (lethal dose: dose causing death in 50% of those exposed) or LC50 (lethal concentration: concentration in air or water causing death in 50% of those exposed) determines the label or signal word. The signal words are as follows (from extension.org):
“DANGER: Any product, which is highly toxic orally, dermally, through inhalation, or causes severe eye or skin burning, will be labeled DANGER… As little as a taste to as much as a teaspoonful taken by mouth could kill an average sized adult.”
- e.g. Great Value® Bleach, Drano® Professional Strength Foamer Clog Remover, and WD40®
“WARNING: Any product which is moderately toxic orally, dermally, or through inhalation or causes moderate eye and skin irritation, will be labeled WARNING. A teaspoonful to a tablespoonful orally could kill the average sized adult.”
- e.g. Finish® Automatic Dishwasher Detergent Powder and Non-acetone Nail Polish Remover
“CAUTION: Any product which is slightly toxic to relatively non-toxic orally, dermally, or through inhalation or causes slight eye and skin irritation, will be labeled CAUTION. An ounce to more than a pint taken orally could kill the average adult.”
- e.g. Lysol® Brand III and Thermacell® Repellent Mats
This figure may be clicked on to view a larger size. The above chart from the National Pesticide Information Center shows how LD50’s/LC50’s determine the signal word and toxicity category of a product.
LD50 is generally expressed as the dose in milligrams (mg) of chemical per kilogram (kg) of body weight. LC50 is often expressed as mg of chemical per volume (e.g., liter (L)) of medium (i.e., air or water) the organism is exposed to. Chemicals are considered highly toxic when the LD50/LC50 is small and practically non-toxic when the value is large. However, the LD50/LC50 does not reflect any effects from long-term exposure (i.e., cancer, birth defects or reproductive toxicity) that may occur at levels below those that cause death. (National Pesticide Information Center)
Toxicity of Thermacell Mosquito Repellent containing d-cis/trans allethrin: d-cis/trans allethrin is labeled Caution category III for mammalian exposure (slightly toxic to relatively non-toxic), non-toxic to birds, and highly toxic to fish and invertebrates. As with anything volatile, chronic exposure (continued exposure over long periods of time) may lead to adverse health effects but studies are lacking on long-term exposures to mosquito repellents of this kind. You may want to watch for allergic reactions and if you suffer from asthma, you may want to exercise caution when using any volatile. In general, my response is to always use things in moderation and mix up the measures I use to combat mosquitos. This means if I want to repel mosquitos on any given day I may sometimes use the Thermacell device or DEET or maybe try to wear long clothing or simply stay inside during the height of mosquito activity.
The Thermacell Mosquito Repellent appears to be very effective at repelling mosquitos according to my observations. Early scientific data supports this. Some of these studies suggest that it also causes mosquito knockdown (insect paralysis) and death. The active ingredient, d-cis/trans allethrin, also poses very little risk to adults, children, and pets. The device itself is lightweight, portable and easy to use. There are a couple of drawbacks to using the Thermacell Mosquito Repellent appliance. One was that I was only able to use two mats per one butane cartridge instead of three mats to one cartridge. Each mat was effective for four hours, but the butane cartridge lasted only eight hours. And the other drawback is that refills could become expensive ($6.99 for three mats and one butane cartridge) if you spend a lot of time outdoors.
Source: The samples used in this review were provided by Thermacell. Please visit their website for more information.
1 Alten B., Caglar S. S., Simsek F. M., Kaynas S., Perich M. J.. 2003. Field Evaluation of an Area Repellent System (Thermacell) Against Phlebotomus papatasi (Diptera: Psychodidae) and Ochlerotatus caspius (Diptera: Culicidae) in Sanlıurfa Province, Turkey, J. Med. Entomol. 40: 930-934. CrossRef
2 Bibbs C. S., Fulcher A., Xue R. D.. 2015. Allethrin-Based Mosquito Control Device Causing Knockdown, Morbidity, and Mortality in Four Species of Field-Caught Mosquitoes (Diptera: Culicidae), J. Med. Entomol. 52: 739-742. CrossRef
3 Dame D. A., Meisch M. V., Lewis C. N., Kline D. L., Clark G. G.. 2014. Field Evaluation of Four Spatial Repellent Devices Against Arkansas Rice-Land Mosquitoes. J. Am. Mosq. Control. Assoc. 30(1):31-36. CrossRef
4 Revay E. E., Kline D. L., Xue R. D., Qualls W. A., Bernier U. R., Kravchenko V. D., Ghattas N., Pstygo I., Müller G. C.. 2013. Reduction of mosquito biting-pressure: Spatial repellents or mosquito traps? A field comparison of seven commercially available products in Israel. Acta Tropica. 127: 63–68. CrossRef
Works like a charm! This is another device that you should keep on you as a part of your arsenal against mosquitoes and the diseases that they carry.
I’ve now had the Thermacell for three years and everytime we use it, it always seems to work for us here in Texas. We’ve used it while walking around the neighborhood, while sitting around a campfire, while working in the yard, and while lounging around outdoors on our patio furniture. Most of those times, I remember there being a gentle breeze too and it still seemed to work well.