There are mosquito apps for your smart phone that are designed to keep mosquitoes away. You can even view a Youtube video that does the same thing. In both cases, a high frequency sound is emitted that scares skeeters away.
This sounds like great technology since most people now have a smart phone. When you go outside, all you have to do is turn on the app and enjoy a mosquito-free environment. No more bites and you don’t need to lather on chemicals.
This is a case of where a little science has been used to create a new gardening myth and make some money.
The Theory Behind Mosquito Apps
Bats use echolocation to find flying insects. They send out ultrasonic frequencies and monitor the reflected sounds. Humans can’t hear these frequencies, but if you could hear them, they would sound something like; ping…ping….ping…ping, where each ping is a burst of sound.
Some insects like moths, beetles, and crickets can hear the bats ultrasonic signal. Some insects will fly away, while others start flying in an zigzag, spiral, or looping pattern to avoid being eaten by the bat.
If this sound scares away insects, then a device that makes such sounds would also scare them away. Smart phones contain the technology to create sounds, so programmers have developed apps that do just that. There are now a dozen or more such apps on the market – some are free. There are also several YouTube videos that give you many hours of sound.
More Science on Bat Calls
The brief description above sounds very plausible, but lets have a closer look at the facts.
Bat echolocation frequency is in the range of 14 kHz to well over 100 kHz. The typical hearing range for humans is between 20 Hz and 20 kHz, with the higher range being lost when we age.
There are two things to notice about this bat echogram. The sound changes in frequency during the duration of each ping, and there are distinct pings. It’s not a constant sound at one frequency.
What Can Mosquitoes Hear?
Mosquitoes hear using their antennae and their hearing is quite good. Males use sound to find the flying females, but until about 2006 it was thought that females could not hear. That is important since it is the females that bite.
It has now been demonstrated that females can hear and that courting pairs will synchronize their tones – a kind of love duet.
Flying females emit a sound around 400 Hz as they flap their wings. Hearing in mosquitoes is developed around this range, and mosquitoes can hear sounds in the rage of 150 Hz to 2 kHz. This is nowhere near the ultrasound range of bats, so they don’t hear bats.
Mosquitoes can’t even hear an approaching dragonfly very well, who’s moving wings emit sound in the range of 20 Hz to 170 Hz.
The most energetic frequencies of human speech are in the range of 150 Hz to 1,000 Hz, and mosquitoes can hear at distances of 10 meters (32 feet). They might be listening to you while you are on the patio deck.
What Sound Do Phone Apps Make?
Most of these apps produce a frequency between 10 kHz and 20 kHz. A value of 14 kHz or 17 kHz seems popular.
The emitted sound is a constant sound – like a piiiiiiiiiiiiiiiiiiing. This is a recording of a YouTube mosquito repelling video. I have two grandchildren, only one could hear this sound. I also tested another YouTube video which was at 15 kHz, and both could here that one. I could hear neither.
The left side of the trace is background noise, with the app off. I then turned the app on to get the higher levels of sound. You can see that this trace looks nothing like the bat sounds.
To be effective you would think that this sound trace should mimic that of the bat?
A Myth is Born
This is a good example of how a bit of scientific knowledge can be used to con customers.
Bats eat mosquitoes and they find their food using sonar. Many people know these facts or are very willing to accept them, and they correct.
Once these “scientific” facts are established it is a short leap to convince people that an app which produces similar high frequency sounds will work. Presto – a sale is made, or should I say thousands of sales are made.
Some phone apps are free, but many have an upgraded version for sale. YouTube videos are free, but you might have to watch some advertising to view them.
Do Smart Phone Mosquito Apps or YouTube Video Apps Work?
Biogents, a mosquito research company gave a phone app a try. Here are some images from their video.
It seems clear to me – the phone app worked. There are no mosquito bits in the palm of the hand that held the phone. 🙂
Requests were made to seven manufacturers of such products to provide their scientific data confirming their apps work. None responded.
There is no scientific evidence that high frequency sounds repel mosquitoes. So even if the apps copied the bat sounds perfectly, it is unlikely they would keep mosquitoes away.
The American Mosquito Control Association reports that, “At least 10 studies in the past 15 years have unanimously denounced ultrasonic devices as having no repellency value whatsoever.” So why do people keep buying them?
There are over 3500 species of mosquitoes, and most have not been tested. But the absence of scientific support does not validate a theory.
The scientific position is clear – high frequency devices do NOT keep mosquitoes away.
What Does Work for Mosquitoes?
You will see from the above list that most mosquito repelling devices either don’t work, or work in a very limited way. So how do you keep mosquitoes from biting?
DEET and Picaridin are still your best choice for both safety and efficacy.
Here are some other posts that might interest you.