Does Thermacell Repel House Flies?

Thermacell is one of the practical solutions against mosquitoes, ticks, and most flies including House flies. The repellent is successfully used to keep House flies away from the patio or from the camp area when in the outback.

Thermacell isn’t efficient at keeping House flies away indoors. The manufacturer doesn’t recommend using it indoors as the product is only made to suit outdoor use.

Thermacell keeps House flies away for up to 4 hours in a 15-feet radius. It only repels flies outdoors as it’s not made for indoor use. The repellent system is also made to keep most other flies away for hours.

House flies can be repelled by both versions of Thermacell. This includes the fuel-powered version and the battery-powered version of the device.

Can Thermacell Really Repel House flies?

Thermacell can repel House flies. It uses Phytochemical allethrin which mimics the natural effects of Chrysanthemum flowers to repel flies, mosquitoes, and ticks.

Thermacell comes in various options from the fuel-powered version to the smart Thermacell device you can control from your smartphone. The basic principles of this device are similar across its options.

Does Thermacell Repel House Flies?

It heats a small mat with Phytochemical allethrin which keeps these common flies away. The device is ideal in open spaces as it releases fumes. Ideal for camping, it can be used at home for evenings out on the patio or in the garden where mosquitoes and flies can be annoying.

How soon does Thermacell work against house flies?

Thermacell takes 15 minutes to create a barrier-like perimeter that keeps House flies away. This interval is required for Thermacell to heat up and repel flies.

Most users note the 15-foot radius of the Thermacell system is realistic as it covers a similar area outdoors. This area is where you need to be situated so that flies don’t bother you.

Wind can create some confusion when it comes to this perimeter. Thermacell works best when there’s no wind as the active ingredients need to disperse in the air and not be carried away with the wind.

How long does Thermacell keep house flies away?

A classic Thermacell refill lasts up to 4 hours of continuous use. The refills are empty after this interval and a warning light comes on alerting the user a new refill needs to be installed to keep House flies away further.

How to use Thermacell to keep house flies away

Both the 15-feet radius and the 4-hour performance are based on conditions where you manage to place the Thermacell system on an elevated surface such as a table. Raising it further is sometimes recommended but the heat of the system raises its active ingredients nonetheless.

Does Thermacell kill House flies?

Thermacell doesn’t kill House flies at first. It paralyzes them. Flies enter the area Thermacell is active in and they drop immediately. Most people assume these flies are now dead, which isn’t the case for the first 10 minutes.

Adult House flies aren’t killed by Thermacell immediately as they can resume flying as soon as Thermacell mats run out. This is due to the active ingredient in Thermacell systems which paralyzes flies and other insects and does not act as an insecticide on flies.

However, studies show that continuous exposure to Allethrin that lasts more than 10 minutes kills flies and other insects. Wind can stop this continuous exposure as can stopping Thermcell systems does. Flies will die eventually, but it might take a few minutes for Thermacell to kill them.

The benefits of Thermacell against house flies

While there are other systems successfully used against House flies, not many of them are practical. Some release heavy fumes in a certain direction only while Thermacell covers an entire radius around it.

15-20 feet house fly-free radius

An area of at least 15 feet is covered by the Thermacell system ensuring House flies do not approach it. It can be installed on the patio to keep the flies from coming to the window attracted to light in the evening.

The radius of the system can be reduced on windy days when active ingredients are spread out quicker. You can combine 2 or more Thermacell systems to cover a larger area.

Not applied on the skin

Insect repellents are normally sprayed on the skin. Thermacell eliminates this issue by acting in the air around you instead of acting directly on you.

No scent

There’s no unpleasant scent to worry about with Thermacell systems. Oher bug sprays can come with an unpleasant odor but Phytochemical allethrin has no unpleasant odors.

Why repel House flies with Thermacell?

House flies aren’t the most dangerous types of flies but they can still cause many health problems, including diseases. While they don’t bite, House flies can still be dangerous.

To keep diseases such as salmonella away

House flies eat all types of food and organic matter including feces. They pick up bacteria and pathogens and spread them to food and other items around the house.

Thermacell can stop them from spreading bacteria to the foods you might be consuming outdoors or while camping.

To prevent food contamination

House flies can contaminate foods and cause serious diseases such as typhoid fever. These flies can land anywhere and as long as there’s the food they aren’t likely to go away.


Thermacell uses Allethrins or a type of insecticide used against flies and other insects. The system uses heat to disperse Allethrin which creates a protected area that repels House flies.

Common in and around homes, House flies are very annoying. Apart from annoying, House flies are also dangerous to human health through the spread of viruses and bacteria. Food contamination is common in areas where House flies can land on food or cooking utensils.

Thermacell can kill common House flies after 10 minutes. The active ingredients in Thermacell systems first paralyze the flies which drop on the ground. It then kills them if it runs continuously for a few minutes. Thermacell is portable and it can be placed anywhere outside of the house to repel House flies.

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