Bug zappers, with their promise of a satisfying zap and a bug-free environment, have been a fixture in backyards and patios for years. The allure is understandable – who wouldn’t want a device that effortlessly eliminates annoying insects? But when it comes to effectively dealing with flies, especially the biting ones that ruin outdoor gatherings, the question arises: Will A Bug Zapper Kill Flies?
The answer, backed by extensive research and expert opinions, might surprise you. While bug zappers are indeed efficient at killing bugs, they are remarkably ineffective against mosquitoes and other biting flies – the very pests most people want to get rid of. Furthermore, their indiscriminate nature leads to the unnecessary slaughter of beneficial insects, disrupting the delicate balance of our ecosystem. And if that’s not enough, the electrocution process can even send a spray of germ-ridden bug fragments into the air.
In this comprehensive guide, we’ll delve into the science behind bug zappers, uncover why they fail to target the flies that bother us, and explore much better alternatives for effective and environmentally conscious pest control.
Why Trust Our Expertise on Bug Zappers?
Our conclusions are not based on guesswork. To bring you the most accurate information, we consulted with leading entomologists and researchers who have dedicated decades to understanding insect behavior and pest control.
We spoke with Dr. Laurence Zwiebel, a distinguished professor at Vanderbilt University with nearly 40 years of experience in insect behavior research, focusing specifically on mosquito olfaction for the past 25 years. His insights into how mosquitoes are attracted (and not attracted) to bug zappers are invaluable.
We also gained expertise from Dr. Leslie Vosshall, a neurobiology professor at Rockefeller University, who has spent 30 years studying insects, with a particular emphasis on mosquitoes and repellency over the last 15 years. Her perspective on the types of insects that bug zappers actually attract is crucial to understanding their limitations.
Further reinforcing our understanding is Professor Jonathan Day from the University of Florida, a medical entomologist with almost 40 years of experience in mosquito and bug research, specializing in mosquito control strategies. His direct field experience provides a practical viewpoint on the real-world effectiveness (or ineffectiveness) of bug zappers.
To ensure a balanced perspective, we also considered the viewpoint of the industry itself, speaking with Brian Provost from Flowtron, a leading bug zapper manufacturer. His insights into the perceived benefits and common defenses of bug zappers helped us address common misconceptions.
Beyond expert interviews, we immersed ourselves in academic studies and publications from numerous university extension offices, ensuring our analysis is grounded in scientific evidence. Combined with our extensive experience writing about insect control – including guides on bug repellents, mosquito-control gear, and fly swatters – we are confident in providing you with well-researched and reliable information about bug zappers and their effectiveness against flies.
Bug Zappers: Effective Killers, But of the Wrong Insects
Two bug zappers shown in a tree.
Bug zappers are highly effective at attracting and killing insects drawn to UV light, but these are often not the flies that bother humans.
Bug zappers operate on a simple principle: they emit ultraviolet (UV) light, a powerful attractant for many insects. This light lures bugs towards the device’s core, where they meet their demise through electrocution between two charged metal grids. And indeed, bug zappers are remarkably efficient at killing insects that are attracted to their bright glow. The problem? The insects they attract and kill are often not the ones causing you grief.
As Dr. Leslie Vosshall succinctly stated, “Bug zappers are good for attracting insects that are attracted to bug zappers.” This crucial distinction highlights the fundamental flaw: mosquitoes and many other biting flies are simply not strongly drawn to UV light in the same way as many nocturnal insects.
A revealing study conducted at the University of Delaware meticulously tracked the insect kill count of six residential bug zappers over a 10-week period. The staggering total of insects zapped was 13,789. However, the number of biting flies, including mosquitoes, among this massive insect graveyard was a mere 31 – a dismal 0.22 percent. The study authors understandably concluded that bug zappers are “worthless for biting fly reduction.”
Echoing these findings, the American Mosquito Control Association cites research from Notre Dame University (though not available online) which similarly found mosquitoes to constitute a tiny fraction of bug zapper catches – just 4.1% and 6.4% in two separate studies over an entire season. The Colorado State University Extension succinctly summarizes the scientific consensus: “No controlled scientific study has shown that these devices reduce mosquito biting rates outdoors.”
The Unintended Victims: Beneficial Insects and Ecosystem Disruption
The ineffectiveness against biting flies is only half the story. Perhaps more concerning is the type of insects that bug zappers do kill. The University of Delaware study revealed that the vast majority of zapped insects were “many thousands of nontarget insects representing a rich taxonomic diversity.” This means bug zappers are indiscriminate killers, eliminating a wide range of insects, most of which are not pests and many of which are actually beneficial.
The researchers from the University of Delaware study expressed serious concern about this indiscriminate killing, stating that even if bug zappers were effective against biting flies, “the resulting destruction of thousands of parasitoids, predators, aquatic insects, and other members of the nocturnally active fauna would be difficult to justify.” Professor Jonathan Day emphasizes the broader ecological impact, noting, “We’re in a big enough crisis with colony collapse with honey bees that I think anything that impacts a beneficial insect population is problematic.”
This wholesale eradication of insects can have ripple effects throughout the ecosystem. The University of Delaware study authors point out the potential harm to nocturnal insectivores like bats and nighthawks, who rely on these insects as a primary food source. By indiscriminately removing insects from the food chain, bug zappers could inadvertently harm these beneficial animals.
An image of bees entering and swarming around a wooden bee hive.
While honey bees are not attracted to bug zappers, many other crucial pollinators, like moths, are highly susceptible to their UV light lure.
While honey bees are fortunately not attracted to UV light and are primarily active during the day, making them largely safe from bug zappers, the same cannot be said for other vital pollinators. Moths, for instance, are highly attracted to light and are crucial nocturnal pollinators, taking over the “night shift for pollination,” according to the US Forest Service. A 2018 study from the Universities of York, Newcastle, and Hull highlighted the significant role moths play in pollination, discovering they pollinate a wide range of plants, including important food crops, and can even carry pollen over greater distances than honey bees, promoting plant diversity. The widespread killing of moths by bug zappers has significant implications for plant pollination and ecosystem health.
Another group of beneficial insects particularly vulnerable to bug zappers are parasitic wasps. These tiny, harmless-to-humans insects are natural enemies of many pest insects. They act as a crucial form of biological control, parasitizing and killing a wide range of agricultural and garden pests like ticks, beetles, flies, caterpillars, and aphids. The University of Maryland Extension even suggests that parasitic wasps may be “the single most important biological control method gardeners have.” By decimating populations of these beneficial wasps, bug zappers can inadvertently worsen pest problems in gardens and agricultural settings.
Professor Day has been a long-standing critic of bug zappers. In a 1997 interview, he declared them “a total waste of money” for mosquito control. In a 2008 interview, he further pointed out a counterintuitive downside: bug zappers can actually lure mosquitoes towards your location. While attracted to the light, mosquitoes are ultimately more drawn to human hosts, meaning they may “come for the light, but stay for the blood,” as the article states. Despite the research on bug zapper ineffectiveness dating back decades, Professor Day notes that most entomologists consider the question definitively answered, with no need for further studies.
This negative view of bug zappers is widely shared. Organizations like Harvard Medical School (“Don’t buy a bug zapper”), Iowa State University (“Bug Zappers are Harmful, not Helpful”), and the Texas Tech University Infant Risk Center (“Don’t use bug zappers”) all advise against their use. This near-unanimous condemnation stems from the scientific evidence of their ineffectiveness against biting flies and their harmful impact on beneficial insects.
The Unpleasant Truth: Vaporized Bug Guts and Potential Health Concerns
Beyond ecological concerns, there’s another, more unsettling aspect of bug zappers: the “vaporized bug guts” phenomenon. The electrocution process is so forceful that it can literally explode insects, sending microscopic fragments of their bodies, including potentially disease-carrying bacteria, into the air.
A 2000 study by Kansas State University researchers investigated this “aerosol dissemination of microorganisms by insect electrocution devices.” The study tracked the spread of bacteria and a bacterial virus during the zapping of house flies. The findings revealed that bug zappers could indeed “play a role in the spread of infectious disease agents.” One of the study authors expressed surprise at the extent of microorganism dispersal, noting that “really significant amounts on the surface of the fly will survive” the electrocution and be spread into the environment. The study found that bug parts could be propelled up to 7 feet away from the zapper.
Professor Day acknowledges this potential health concern, stating that if a fly carrying salmonella is zapped near a picnic table, “there is a possibility of bacteria on the surface of the fly getting dispersed out into the air and potentially onto your sandwich.” While he concedes that a fly simply landing on your sandwich might pose a greater risk, the idea of aerosolized bug parts, potentially carrying pathogens, is certainly not appealing, especially in areas where food is prepared or consumed.
While indoor bug zapper use might mitigate the ecosystem damage, the issue of bug fragment dispersal remains. Furthermore, the bright UV light emitted by bug zappers can be disruptive indoors, especially at night. While a bug zapper might eventually eliminate a single fly trapped in a room, the drawbacks and potential health concerns outweigh the limited benefits.
The Manufacturer’s Stance: Bug Zappers Have Their Place
To present a complete picture, it’s important to consider the perspective of bug zapper manufacturers. Brian Provost from Flowtron argues that bug zappers, especially when used with attractant cartridges, can be effective against mosquitoes. He mentions overseas orders for mosquito-borne disease reduction as evidence of their utility in certain contexts. Regarding ecological impact, he suggests that the remains of zapped insects simply become part of the food chain on the ground.
On the issue of pollinators, Provost “strongly disagreed” that bug zappers harm them, asserting that butterflies and honey bees are not attracted to UV light. He cites anecdotal feedback from apple orchard owners who are satisfied with bug zappers because they supposedly don’t affect pollinators crucial for apple production. He also dismisses concerns about aerosolized bug parts as something they are “not pestered about.”
Online reviews for bug zappers are often positive, with many showcasing photos of devices covered in dead insects. However, as pest control expert Joe Conlon points out, anecdotal internet evidence is unreliable for mosquito control claims. Without entomological expertise, it’s impossible to identify the types of insects pictured in these reviews, and assess the broader ecological impact of the zappers.
What to Use Instead of a Bug Zapper for Fly Control
Fortunately, there are much more effective and environmentally responsible ways to manage flies and other biting insects in your yard and patio. Experts overwhelmingly recommend focusing on repellents and preventative measures rather than indiscriminate killing devices like bug zappers.
Dr. Laurence Zwiebel emphasizes the benefits of repellents, stating, “Repellents don’t kill anything. They just say ‘don’t bite this, don’t eat that.’ Go off and live a long, happy life.” He rightly points out that the goal should be to “push [insects] away, you don’t want to pull them in” – a direct contrast to the attract-and-kill approach of bug zappers.
1. Bug Repellent Sprays: For personal protection, repellent sprays are a top recommendation. Repellents containing 20% picaridin are as effective as DEET but are odorless and less likely to damage plastics. These repellents effectively deter mosquitoes and other biting flies from landing on your skin.
2. Spatial Mosquito Repellents: For patio and deck areas, spatial repellents offer a convenient alternative to sprays. These devices release a vapor repellent into the air, creating a protective zone. They are effective in still air conditions and can provide localized relief from mosquitoes.
3. Fans: A simple yet highly effective method, especially against weak-flying mosquitoes, is using fans. A strong breeze disrupts mosquito flight and makes it difficult for them to reach you. Directing airflow low to the ground, as recommended by experts like Joe Conlon and Professor Day, is particularly effective as some mosquito species prefer to bite lower extremities and seek shelter under furniture.
While futuristic solutions like the Photonic Sentry laser mosquito zapper remain a dream for now, the readily available alternatives of repellents and fans offer practical, effective, and ecologically sound ways to manage flies and mosquitoes without the drawbacks of bug zappers.
Conclusion: Rethink the Bug Zapper for Fly Control
While the satisfying zap of a bug zapper might seem like an effective way to eliminate flies and other annoying insects, the reality is far more complex. Bug zappers are largely ineffective against mosquitoes and biting flies – the primary targets for most users. Instead, they indiscriminately kill vast numbers of beneficial insects, including pollinators and natural pest predators, disrupting the delicate balance of our ecosystem. Furthermore, they pose potential health concerns by aerosolizing bug fragments and pathogens.
For effective and responsible fly and mosquito control, opt for proven methods like repellent sprays, spatial repellents, and fans. These alternatives focus on deterring pests without harming beneficial insects or the environment, providing a much better solution for a truly enjoyable and bug-free outdoor experience. Before you plug in a bug zapper, consider if you’re really zapping the bugs that bother you, or just contributing to a less healthy environment.
