Bug Zappers Are a Terrible, Useless, Destructive Invention

Sam Westreich, PhD

They work, all right — but probably not on the bugs you want to see dead.

Look him in the cute widdle face and tell him that you want him dead.Photo by Henry Lai on Unsplash

Growing up in the Midwest region of the United States, we didn’t just have to coat ourselves in sunscreen — we also needed bug spray.

And I’m talking about the serious stuff, with nasty, neurotoxic DEET in them. It turns out that the “land of ten thousand lakes” offers a lot of stagnant water for mosquitos to breed in, and they emerged in swarms as the sun dropped below the horizon each night. Sometimes, swarms felt so thick that you were practically choking, mosquitoes eagerly flying towards any source of carbon dioxide — including your mouth.

There’s a whole host of bug-killing methods marketed to help humans enjoy their Midwestern picnics and outdoor time beyond around 5:00 PM. Along with bug sprays, there are:

  • lanterns,
  • candles,
  • various products derived from the Citronella (lemongrass) plant,
  • sonic noise emitters,
  • wearable gadgets,
  • heating coil diffusers,
  • and the classic bug zapper.

I’ve seen most of these in action. They’ve been reviewed.

Most of them don’t work, sadly. There’s a reason why Midwesterners stick with the neurotoxic chemical-infused body spray. But one of them is not just ineffective; it’s actually making matters worse.

(Actually, that’s a lie; sonic devices that claim to drive off mosquitoes may also make things worse by attracting the very insects they promised to scare, encouraging even more itchy bites.)

I could write a whole article on the useless methods for fighting mosquitoes, but I want to talk about one device: the bug zapper, and why we need to get rid of them.

Here’s the gist: they don’t kill mosquitoes, but they kill pollinators, friendly insect-eating bugs, and they spread infectious diseases and can make you sick.

And yet, they’re still widely sold.

Here’s why you should get rid of yours.

Mosquitoes target sweat, heat, and breath — not light

Mosquitoes have a number of ways to find their target, that being any creature with delicious warm blood for them to suck. They can use:

  • Exhalations: mosquitoes detect the carbon dioxide that we exhale, from up to 100 feet away. This is the first method of prey detection.
  • Sweat: mosquitoes have a powerful sense of smell, and track the scent of our sweat. This also has a significant range, similar to carbon dioxide detection.
  • Body heat and movement: mosquitoes need both vision and smell to identify a target. Once they smell the aromas of carbon dioxide and sweat, they’ll look for warm, moving targets.

Mosquitoes also seem to have some attraction to other features, such as color (red, orange, cyan, and black).

But one thing missing from that list of attractants?


It makes sense, after all; most animals don’t emit any sort of light, so why would mosquitoes target something bright? Additionally, since mosquitoes don’t need to navigate in the same way that moths do, there’s no reason for them to use light to orient themselves.

So bug zappers aren’t going to do anything to catch mosquitoes. The only mosquitoes drawn to their light will be ones that blunder into it by accident.

What about bug zappers that make sonic noises?

Some bug zappers also tout the fact that they additionally emit sonic waves, claiming that these are able to drive away “mosquitoes, insect, rat, rodent, flies, ant, fleas and more pests”.

We already know that the bug zapping part isn’t effective unless the mosquito literally blunders in, so this already seems suspect. But the scientific evidence is in; high-pitched frequencies do nothing to repel mosquitoes.

Companies that produce these devices have a few claims as to why they might work, but those claims don’t stand up to examination.

“The frequency imitates the buzzing of a predator, like a dragonfly, which scares off mosquitoes!”

Most devices, however, play ultrasonic sounds at around 15 kHz, which is much higher frequency than dragonfly wings (which flap/buzz at between 20–170 Hz).

There are plenty of videos of amateur mosquito battlers testing these devices — and most of them (all of those not sponsored by a company that makes ultrasonic devices) show that the mosquitoes are completely undeterred by high-pitched sounds. If anything, the sonic frequencies may actually increase biting rates.

But those zappers are killing the insects you want most

Bug zappers don’t attract mosquitoes. They also don’t attract biting flies, for many of the same reasons (these flies hunt by looking for signs of humans, and don’t care about bright lights, so they aren’t attracted to the zapper).

Instead, they mainly attract and kill moths and parasitic wasps. Both of these creatures should be loved, not killed.

Moths are important pollinators; alongside bees, they visit many flowers, and some flowers rely entirely on moths for pollination (flowers that bloom at night, for example, will be visited more by moths than bees). Buttercups, honeysuckle, white clover, and yucca plants are all pollinated thanks to moths. Additionally, with their furry bodies, moths carry more pollen from flower to flower than smooth-bodied bees.

Parasitic wasps are not the nasty, big, stinging wasps that most of us think about when we hear the name. Instead, these are the tiny little yellow-and-black banded creatures, less than half an inch long. They have slender bodies and often buzz curiously around us when we enter gardens.

Instead of stinging us, however, these wasps prey on other insects, primarily pests like aphids, tomato hornworms, corn borers, and various other caterpillar and worm species that would eat away our garden plants. Gardeners work to encourage these parasitic wasps to stay in their garden area, often laying out shallow water baths or planting flowers to attract them.

These two types of insects are the ones you want to preserve — and they’re the majority of the bugs dying in zappers.

Getting showered in insect guts

There’s (yet) another problem with bug zappers: what happens to the bugs that get zapped. They explode, which, although viscerally satisfying, can create a health hazard.

One study showed that “airborne insect particles” could travel as far as seven feet from the zapper. If the zapper happens to be near any food, or surfaces, they could be coated with bits of bug — as well as any bacteria that happen to be living on or in the insect. (The heat from getting electrified is enough to make the bug explode, but not enough to sterilize any bacteria.)

This means that using the zappers around any food, like at a picnic, or even around people, is not a good idea — unless you want them seasoned with microscopic splattered insect remains.

Combine this with the inability to target biting insects, including mosquitoes, and bug zappers should be zapped right out of your shopping cart or summer plans.

In summary: don’t zap the good bugs

Bug zappers sound effective, because you can see them frying the bugs that are drawn to their light — but the bugs that are drawn in are not the ones we want to kill. We want to keep pollinating moths and pest-killing parasitic wasps alive, but those are the primary victims of bug zappers.

Instead, the best bug repellant choice is still going to be a chemical compound. New York Times’ Wirecutter reviewed bug repellants and found that the best choice were those that contained picaridin, a spray with similar effectiveness as DEET but with fewer risks and downsides.

It might not be fun to put on bug spray, but at least it’s effective — and you can pair it with white and green colors for even more mosquito deterrence. Choose this over the bug zapper, and help out the flowers and vegetables in your garden and neighborhood.

Be kind to moths! Say no to the zapper!


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A microbiome scientist working at a tech startup in Silicon Valley, Sam Westreich provides insights into science and technology, exploring the strangest areas of biology, science, and biotechnology.

Mountain View, CA

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