Bug sprayers kill countless. Unfortunately, they destroy the wrong pests. The indiscriminate eradication of mosquitoes and other biting insects can interrupt pollination and upset the environment. Additionally, their electrocution can release disease-ridden bug bits into the air. Every mosquito expert and university extension office we spoke to opposed bug zappers. Better methods exist to eliminate pests or avoid bites.
Why you should trust us
We interviewed Vanderbilt University biology and pharmacology professor Laurence Zwiebel, PhD, about bug zappers. To understand how olfaction—the sense of smell—drives mosquito behavior, Zwiebel has studied insects for almost 40 years and mosquitoes for 25.
We also corresponded with Rockefeller University neurobiology professor Leslie Vosshall, PhD. A 30-year insect researcher, Vosshall has focused on mosquitoes and repellency for 15 years.
We also learned from University of Florida Professor Jonathan Day. He has studied mosquitoes and other bugs for nearly 40 years with a PhD in medical entomology. His specialty is mosquito control.
We interviewed Brian Provost, international sales representative and customer service manager of Flowtron, a renowned bug zapper maker, about the devices’ benefits and typical complaints.
We also read as much as we could about bug zappers, including academic papers and university extension office materials.
I’ve written on bug repellents, mosquito-control gear, fly swatters, ant killers, and why you should avoid essential oil bug repellents. I interviewed many academics, product manufacturers, the Environmental Protection Agency, and Joe Conlon, then technical adviser of the American Mosquito Control Association, for these publications. I keep honey bees, which helps me understand pollination and insects.
Bug zappers kill the wrong bugs
Bug zappers use UV light to draw bugs to the middle (typically between two metal grids) and electrocute them. By attracting bugs with its light, bug zappers kill them effectively. Not killing your bothersome bugs is the sole issue.
Rockefeller University neuroscience professor Leslie Vosshall said bug zappers attract insects that like them. This usually excludes mosquitoes and other biting insects. Only 31 of 13,789 insects killed by six household bug zappers over 10 weeks were biting flies, according to a University of Delaware study. What a terrible 0.22 percent. This explains why the study found bug zappers “worthless for biting fly reduction.” The American Mosquito Control Association reports that Notre Dame researchers discovered that “mosquitoes comprised merely 4.1% and 6.4%, respectively, of the daily catch over an entire season” in two bug zapper experiments (neither of which is online). According to Colorado State University Extension, “No controlled scientific study has shown that these devices reduce mosquito biting rates outdoors.”
Quite terrible, right? That’s worse when you know which bugs are kill. Delaware study says zapped bugs contain “many thousands of nontarget insects representing a rich taxonomic diversity.” The University of Delaware study found that “Even if targeted biting flies were effectively controlled by electric zappers, the resulting destruction of thousands of parasitoids, predators, aquatic insects, and other members of the nocturnally active fauna would be difficult to justify.” Jonathan Day, University of Florida professor, said, “We’re in a big enough crisis with honey bee colony collapse that I think anything that impacts a beneficial insect population is problematic.”
The repercussions of bug removal are unknown. The University of Delaware study worries about bug zappers disrupting the food chain for bats and nighthawks, which eat insects at night.
Thankfully, honey bees don’t like light or roam in the evenings, when insect zappers work best. Not all pollinators survive. The US Forest Service says moths “take over the night shift for pollination,” diving straight into any bright light. In 2018, the Universities of York, Newcastle, and Hull concluded that “moths may play a much broader role as plant pollinators than previously suspected.” The study discovered that moths pollinate many plants, including peas and soybeans, by tracing pollen DNA. The study found that moths could transfer pollen farther than honey bees, which “might help to prevent inbreeding among plants.” Conclusion: We should stop mass moth killing.
Day claims that parasitic wasps bear “the bulk of the brunt when it comes to bug zappers.” These tiny, innocuous insects lay eggs in other insects and kill them. The Virginia Cooperative Extension (PDF) states, “They are very important in agriculture, attacking a wide range of insect pests that feed on important crops.” Wasps kill ticks, beetles, flies, caterpillars, and aphids. According to the University of Maryland Extension, parasitic wasps may be “the single most important biological control method gardeners have.” Not the type of insect we want to electrocute.
Day has opposed bug zappers for years. He began an interview by saying, “I’m surprised bug zappers are even still around, or even still a question.” He noted in a 1997 interview, “They are a total waste of money. Bug zappers won’t kill mosquitoes, horseflies, dog flies, or deerflies. Day remarked in a 2008 interview that zappers attract mosquitoes. “When they get closer,” Day added, “the humans sitting on the patio will be much more attractive.” According to the story, mosquitoes “come for the light, but stay for the blood.” Both Delaware and Notre Dame conducted 1980s and mid-1990s research. We questioned Day why no recent studies reported this. “Most medical entomologists feel the question has been answered,” he said.
These studies and experts are not alone in opposing bug zappers. It appears to be practically universal. Harvard Medical School (“Don’t buy a bug zapper”), Iowa State University (“Bug Zappers are Harmful, not Helpful”), and Texas Tech University Infant Risk Center provided similar advice. All say to avoid bug zappers at all costs. These are just a handful of our findings.
Vaporized bug guts, anyone?
This is where things get uncomfortable and gross. The force with which bug zappers electrocute bugs can blow off their hair, legs, and wings and vaporize them. These aerosolized bug bits have spread any sickness they carry. Lovely, eh?
In 2000, Kansas State University researchers published a report in Current Microbiology on the “spread of bacteria and a bacterial virus during electrocution of house flies.” Bug zappers “could play a role in the spread of infectious disease agents.” One study author noted, “We were surprised to see as much microorganism dissemination as was the case.” We anticipated a few bacteria may spread, but we’re seeing extremely considerable numbers on the fly’s surface will survive. The study found bug pieces can be misted almost 7 feet.
We questioned Day. A zapper at a picnic table could spread salmonella-carrying bacteria on the fly’s surface, “possibly onto your sandwich.” However, “if you look at some of the things that flies feed on, probably the fly walking on your sandwich is way more dangerous than you vaporizing the fly above your sandwich.”
According to anecdotes and commenters, using a bug zapper indoors merely means you still have bug guts but avoids mass carnage. Be careful with placement because bothersome bugs commonly live in kitchens or near food. Indoor use causes gaudy blue light, which is especially annoying at night. If you isolate a single bothersome mosquito, fly, or other bug in a room, close the door, and wait, it may accidentally enter the light. Problem fixed.
Bug zapper manufacturers love them anyway
We interviewed Flowtron’s international sales agent and customer service manager, Brian Provost. He opposed these views. With an attractant cartridge (entomology professor Day called them “the latest marketing gimmick”), bug zappers kill mosquitoes, and Flowtron gets a lot of orders from overseas because people “want them to reduce mosquito-borne diseases such as malaria, encephalitis, West Nile virus, yellow fever, things like that.” As for bug zappers disrupting the environment, Provost said “the remains [of the dead bugs] go to the ground, where it’s still a food source for bugs and smaller insects.”
Provost “strongly disagreed” that bug zappers damage pollinators since butterflies and honey bees are not light-sensitive. He said, “I’ve spoken to people that have had apple orchards and they are very happy because it’s not affecting any of the pollinators which they of course want for apple production.”
Regarding disease-ridden misted bug bits, Provost said, “I’ve pretty much heard everything from the good to the bad to the sublime to the bizarre and honestly that’s not something we get pestered about.”
Bug zapper reviews on Amazon and other sellers are generally positive, however this is anecdotal. Conlon said, “when it comes to mosquito control, you can’t trust anything anecdotal from the Internet.” Numerous reports show insect zappers coated in dead bugs. It’s impossible to identify bugs without entomological training. The ecosystem’s impact—whether the zapper is attracting new bugs and whether the bug population drop has affected other species—is also unknown.
What to use instead of a bug zapper
We recommend bug repellant spray or mosquito-control gear for patios and yards. Laurence Zwiebel, Vanderbilt biology and pharmacology professor, said, “Repellents don’t kill anything. Just “don’t bite this, don’t eat that.” Take off and live long, happy.” He added, “You want to push [insects] away, you don’t want to pull them in.”
Spray repellant is our initial suggestion. We propose a 20% picaridin solution, which works as well as DEET. Picaridin is odorless and plastic-safe, unlike DEET. We recommend both varieties in our best bug repellents guide.
If you’re on a patio or deck and want to avoid spray repellent, use a spatial repellent. A mild repellent mist from this tabletop device protects a small area from insects. While researching our patio and yard mosquito-control gear guide, we found that they function if there’s no breeze.
Fan is a third option. A powerful breeze from our fans is too strong for mosquitoes, who are weak fliers. Zwiebel suggested buying a huge ass fan to blow air over guests and himself to decrease insects on a deck or backyard.
Although Conlon likes fans, he advises keeping airflow below table level since some mosquitoes, particularly Zika-carrying ones, “tend to prefer the lower extremities to bite” and “like to hide underneath outdoor furniture.” In high winds, mosquitoes will “go lower and lower into the air column until they get into that transition zone right above the ground where there is no wind and they fly in that.” Day points his fan low.
Finally, we hope Intellectual Ventures’ mosquito-zapping laser Photonic Sentry will become available. Someday. We can only dream now.
