Do bug zappers kill mosquitoes?
Quick answer
No — bug zappers kill almost no mosquitoes. Mosquitoes hunt the CO₂ and heat your body gives off, not ultraviolet light, so they largely ignore the zapper. In one summer-long study of 13,789 insects killed by a backyard zapper, just 8 were mosquitoes — the rest were moths, beetles, and other beneficial insects.
Why it doesn't work
Bug zappers attract insects with ultraviolet light, exploiting positive phototaxis — the hardwired flight-toward-light response of many night-flying insects. Mosquitoes are the wrong target for this trick. Host-seeking female mosquitoes do not navigate to a blood meal by light. They orient to a plume of exhaled carbon dioxide, then refine their approach using lactic acid, ammonia, and other skin volatiles, convective body heat, and water vapor. A glowing purple grid emits none of these cues, so it is invisible to a mosquito’s host-seeking program.
The landmark field measurement is Frick & Tallamy (1996), who collected and identified every insect killed by suburban-yard zappers over an entire season. Of 13,789 insects electrocuted, biting flies (mosquitoes and others) made up roughly a quarter of one percent. The overwhelming majority were harmless or beneficial: moths, beetles, parasitic wasps, and aquatic insects that are food for fish and birds — including predators and parasitoids that suppress pest populations. A zapper is therefore not neutral; it removes the natural enemies of the very pests you want gone, while barely touching mosquitoes.
There is a subtler harm. Each spark aerosolizes the insect’s body. A 2000 study (Broce, Kansas State) showed zappers can disperse a mist of insect parts — and any bacteria or viruses they carry — up to two meters, which is a food-hygiene concern on a patio, not a mosquito-control benefit.
Some "mosquito" zappers add a CO₂ cartridge or chemical attractant. Adding real attractant changes the math — but at that point the working part is the lure-and-capture, not the UV grid. The light is decoration. If you want to suppress the biting females in your yard, you have to emit the cues they actually follow and capture them — which is what a CO₂ + heat trap does.
References
- Frick, T.B. & Tallamy, D.W. (1996), "Density and diversity of nontarget insects killed by suburban electric insect traps," Entomological News 107(2):77–82.link pending verification
- Broce, A.B. et al. (2000), on bacterial/viral aerosolization by electrocutor traps.link pending verification
- Gillies, M.T. (1980), "The role of carbon dioxide in host-finding by mosquitoes (Diptera: Culicidae): a review," Bulletin of Entomological Research 70:525–532.link pending verification
What to do instead
The honest answer isn't "give up" — it's to target the host-seeking females directly. A CO₂ + heat trap broadcasts the breath-and-body cues mosquitoes actually follow, drawing them away from you and capturing them, without spraying pesticide across your yard.
See the SkeeterSwitch bundleCommon questions
Do bug zappers kill any mosquitoes at all?
A negligible number — biting flies were about 0.25% of the catch in the definitive field study. Almost everything a zapper kills is a harmless or beneficial insect.
Why are mosquitoes not attracted to the light?
Host-seeking females navigate by CO₂, skin odor (lactic acid, ammonia), and body heat — not by UV light. A zapper emits none of the cues they follow.
Are bug zappers bad for my garden?
They can be. They kill pollinators and the predatory and parasitic insects that naturally control pests, and they can aerosolize insect debris near where you sit.
What about zappers with a CO₂ or chemical attractant?
Adding real attractant is the only thing that draws mosquitoes — but then it's the lure and capture doing the work, not the electric grid.