You’ve likely heard of mosquito repellents that emit ultrasound. It might be a plug-in device, a battery-operated one, or you can download an app for your mobile if you like. Choices are plenty.
But have you ever wondered what it is about ultrasound that prevents those tiny pests from coming in? Or, how do these devices work?
Short answer: they don’t!
Well, that’s a bummer. However, before I explain why ultrasonic mosquito (and other pest) repellents do not work, let’s first explain how they supposedly work.
The device advertisers will explain to you that ultrasound mimics the sound that male mosquitoes emit. And what does it do? Supposedly it repels female mosquitoes since, apparently, female mosquitoes do run into random males in the woods and would rather prefer to avoid them.
Thus, yeah, it’s genius. Only female mosquitoes suck blood, which is true, therefore the objective is achieved. Alternatively, some devices claim to emit the sounds of dragonflies or bats, who are both predators of mosquitoes and thus must be avoided at all costs.
One more explained mechanism of action by sonic repellent manufacturers is that they emit sounds that cause discomfort to pests, or even damage their brains (yes, mosquitoes have brains). And, since pests do not want their brains damaged, they move out.
Regardless of the claimed mechanism of action, these repellents emit sound. The sound is not audible to humans, it repels blood-sucking mosquitoes, and YOU can enjoy a sting-free evening in your room. Great!
The only problem, it does not work. How so?
- Male mosquitoes do not emit ultrasound. Mosquitoes make a buzzing sound which, as you know, is very audible and annoying to humans. It depends on the species, but mosquitoes emit sound that is 700-900 Hz, which is well in the human hearing range. Thus, if a repellent were to use a male mosquito’s sound to repel females, then it wouldn’t be ultrasonic. It’d be quite audible to you.
- Mosquitoes do not hear ultrasound. For example, yellow fever mosquitoes (of course, species differ, but not by much) hear between 100 and 500 Hz. Ultrasound starts from 20,000 Hz, and mosquito hearing is way below that. Thus, how would a female mosquito be deterred by an ultrasound that does not mimic male buzzing, and that the female herself cannot hear? Besides, mosquitoes can hear at distances up to 10 meters (33 ft). Not very useful if you want a mosquito-free zone larger than that.
- Females do not avoid males selected by their sound. Males indeed locate females based on the sound that they make, and females indeed produce slightly lower sounds than males (since they are bigger), but the opposite does not work. Females avoid males by detecting their scent, and only after they have recently mated. Otherwise, female mosquitoes do not mind male presence at all.
- Tests show they do not work. There are plenty of studies testing whether ultrasonic pest repellents reduce the amount of pests. And the conclusions unequivocally are that they do not. And I’m not just talking about mosquitoes; scientific studies show that ultrasonic pest repellents and deterrents just do not work. At best, it improves your perception, and you forget about mosquitoes.
But what does work to repel mosquitoes?
We should be done by now, right? But wait, if ultrasound mosquito repellents do not work, what does? In the insect world, one of the most important senses is scent. Thus, scent-based repellents are your best choice. There are several chemicals or natural oils that repel mosquitoes, just as there are several methods of application.
Mosquito candles work well, and scent dispensers also give promising results, just as sprays that you apply on yourself. These are all effective methods and should be the ones you use. On the opposite end, quack products such as bracelets and ultrasonic devices do not.
Want to dive deeper into the world of mosquitoes? Read “The Mosquito: A Human History of Our Deadliest Predator” by Timothy C. Winegard.
A story of how mosquitoes shaped human history.
Disclaimer: I earn a commission if you buy the book through my link.