You may have seen devices or even apps you can charge on your phone that emit ultrasonic sounds only mosquitoes can hear. The manufacturers claim these sounds can repel mosquitoes.
It’s a nice idea, no more dousing yourself with repellents or using unpleasant chemicals. Some of these devices have been around for a few years, but do they work?
Unfortunately, there is no scientific evidence to back up these claims but let’s dig a little deeper!
How Does an Ultrasonic Pest Repeller Work?
Put simply, they produce ultrasonic sound waves that are not perceptible to humans, but the mosquitoes can hear. The mosquitoes and other pests hate the sound, so they stay away. At least that’s the theory!
The sounds they produce are often cited as being that of their predators. Some manufacturers claim their devices reproduce the ultrasonic signals emitted by bats. Others claim to imitate the sound of a dragonfly wing beats.
Then, some claim to imitate the sound of a male mosquito. The logic is that a female has already mated, and as she only needs to mate once, she will flee the male.
However, research has shown that it’s the males that are attracted to the sound of a female in flight. Additionally, it is thought that the females, who are responsible for biting, have very little sensitivity to sound.
Different Devices Using Ultrasonic Repellers
Innovative companies have found many different devices to emit sound waves, which they claim are at a frequency we can’t hear but will disturb a mosquito’s nervous system and repel it.
Here are some of the devices developed over the years, although there is no proof they work.
- You can find apps you can download to your phone. Some produce a sound frequency similar to bats. The mosquitoes don’t like the sound so they won’t come near.
- LG produced a telephone with built-in mosquito-repelling technology, using ultrasonic sound waves.
- Band FM radio station sent out an ultrasonic signal of 15 kHz along with radio broadcasts. The signal was meant to imitate the sound of dragonflies which is meant to keep mosquitoes away.
- An air-conditioner that emits sounds in the frequency range, between 30 kHZ and 100 kHz to repel mosquitoes. However, an air-conditioner can make your home less welcoming for mosquitoes by reducing humidity, cooling the room temperatures and the continuous air circulation making it harder for the skeeters to follow our CO2 trail.
- Mosquito repelling TV’s that emit ultrasounds as you’re watching your favorite programme have also been tried.
- Plug-in ultrasonic devices – these can use different frequencies and are advertised as repellents for different pests.
- Ultrasonic repellent watches and bracelets
- Clip on devices that can be worn as a pendant or clipped on a backpack
You can see that people are very inventive in finding different equipment for producing an ultrasonic device.
Can Mosquitoes Hear?
For these devices to work, mosquitoes need to be able to hear. Until recently, it was thought they could only hear at a distance of a few inches.
Recent research has discovered mosquitoes can “hear” grace their antennae with fine hairs. The distance from which they can hear depends on the frequency. Male mosquitoes can hear specific frequencies up to a distance of 32 feet. For female mosquitoes, the distance is probably less.
No Proof Ultrasonic Repellers Work
Do ultrasonic devices repel mosquitoes? Although the explanations of producing sounds similar to predators or male mosquitoes sound quite feasible, there is no scientific evidence to support these ideas.
Ultrasonic devices have been around for years. A scientific review of an ultrasound repellent was published as early as 1974.
The FTC has investigated and issued warnings to several manufacturers of ultrasonic devices dating as far back as 1985. The reason for the warnings, the manufacturers make claims, of which there is no reliable scientific evidence to back up the claims (that ultrasonic devices repel certain pests).
There have been successful prosecutions of ultrasound sellers, but this seems to have had little effect on deterring manufacturers from producing new models or the public from continuing to buy them.
Ultimately, this could be dangerous for the public if they stop using other protection methods, leaving themselves at risk of the many diseases transmitted by mosquitoes.
In 2008, The Cochrane Collaboration produced a review article of 10 entomological studies that had tested ultrasonic repellent devices. The result – there was no evidence in the studies of any repelling effect of the ultrasonic devices. Hence, they shouldn’t be promoted or used.
They go further and state:
There was no evidence in the field studies to support any repelling effects of EMRs, hence no evidence to support their promotion or use. Future randomized controlled trials are not proposed as there was no suggestion in the field studies that EMRs (electronic mosquito repellents) show any promise as a preventive measure against malaria.
Other tests have shown that ultrasonic repellers are not effective, even when used over a wide range of frequencies.
Even worse, one test suggests that electronic mosquito repellers can increase biting frequency. The test was carried out with Aedes aegypti mosquitoes and found that biting rates increased by 20% to 50% when the repellers were turned on. The sound frequencies used ranged from 9.6 kHz to 18.2 kHz.
The American Mosquito Association states clearly these devices don’t work.
Nonetheless, one paper in India suggests that frequency ranges of 38-44 kHz can be used effectively to repel the mosquitoes and flies. Upon reading the article, you will find no reference to any tests with mosquitoes. The paper is about the electrical device, not about its so-called repellent capabilities. The report was written by a Doctor from the Department of Electronics & Communication Engineering!
In August 2016, the New York Attorney General issued cease and desist letters demanding companies to stop advertising ineffective products as “Zika-Preventive”. Two of the products were ultrasound devices. In the press release, it states “Numerous scientific studies have found that ultrasonic devices do not repel mosquitoes, and may even attract mosquitoes”.
What Should I Use To Repel Mosquitoes?
Understandably, people would like to think an electronic mosquito repellent could work. After all, it would be great to get rid of all house pests without having to use anything poisonous, unpleasant, or wear special clothing. But unfortunately, no research shows that an ultrasonic mosquito repeller works.
The Center for Disease Control (CDC) recommends using the Environmental Protection Agency (EPA) registered insect repellents, including DEET, Picaridin, Oil of lemon eucalyptus, Para-menthane-diol, 2-undecanone, or IR3535. EPA registered repellents are proven safe and effective. Find the repellent that’s best for you using the EPA search tool.
Mosquito coils and Thermacell devices can also be used. They both utilize the pyrethroid insecticide and will be more effective when there is not much wind.
Mosquito nets are very effective at keeping mosquitoes away from you when you sleep. They can be insecticide-treated or untreated. If mosquitoes are known vectors of disease in your area, then a treated net is the better choice.
Insect Shield repellent clothing is another EPA registered product you could use. The clothing is impregnated with permethrin to provide an odorless repellent that is effective against several insects. The items should retain their repellency for the life of the clothing or 70 washings. Insect Shield gear has been proven and registered to repel mosquitoes, ticks, fleas, midges (no-see-ums), and flies.
The alternative to using repellents is to wear long-sleeved shirts, trousers, and a mosquito head net.
