Dealing with flies buzzing around your head or landing on your food is a common outdoor nuisance. Beyond being irritating, flies can carry germs and bacteria, making it crucial to keep them away from your living spaces and dining areas. Houseflies and blow flies, often termed “filth flies” by scientists, are the most frequent culprits around homes. While a few flies might be manageable, a full-blown infestation requires a more strategic approach. To help you reclaim your outdoor areas, we’ve consulted with experts to understand the causes of fly infestations and, more importantly, how to effectively deter flies outside your home.
- Dana Nayduch, research leader of the Arthropod-Borne Animal Diseases Research Unit at the United States Department of Agriculture
- Karim Gharbi, entomologist and horticulturist with Colorado State University Extension
- Edwin R. Burgess IV, assistant professor in medical and veterinary entomology at the University of Florida
:max_bytes(150000):strip_icc()/get-rid-of-flies-outside-getty-1023-c10a28ccd1ac4458b8501711a2873ec1.jpg)
Alt text: Outdoor patio scene with a few flies buzzing around, highlighting the common problem of flies in outdoor living spaces.
Recognizing the Signs of a Fly Infestation Outdoors
A few flies on your porch or patio might be a minor annoyance, easily dealt with. However, the signs of a developing fly infestation are more pronounced and require attention:
Emergence of Larvae (Maggots)
One of the most telling signs is the appearance of larvae, commonly known as maggots. You might find them in your outdoor trash cans, compost bins, or around decaying organic matter like pet waste or deceased animals. Housefly and blowfly larvae are small, white, worm-like creatures. Even if you don’t see the larvae themselves, noticing movement within your trash when you open the lid can be an indicator. In some cases, you might even witness maggots moving in large numbers across driveways or patios as they seek suitable pupation sites.
Presence of Yellow Jackets or Paper Wasps
“Scavenging hornets, like yellow jackets and paper wasps, are often drawn to the same food sources that attract flies,” explains Karim Gharbi, horticulturist at Colorado State University Extension. “If you have decaying meat in your garbage, it will attract flies, and it will also attract yellow jackets seeking a protein meal.” These wasps are not only attracted to the same food sources as flies, but they may also prey on fly larvae if the maggot population is substantial. The presence of increased wasp activity can be an indirect sign of a fly breeding ground nearby.
Increased Fly Activity and Swarming
As larvae mature and pupate, young adult flies emerge, sometimes within days depending on the temperature. This emergence is often marked by a noticeable increase in fly activity around your outdoor spaces. You’ll see them buzzing around, actively searching for new food sources and engaging in mating behaviors to begin a new reproductive cycle. This “flying dance party” is a clear sign of a recent or ongoing fly infestation.
Clusters of Fly Specks
Even if you don’t constantly see the flies themselves, their presence can be revealed by what they leave behind. Fly droppings, often appearing as clusters of small black or dark spots, are particularly noticeable on light-colored surfaces like white patio furniture, walls, or windowsills. These spots are a clear indication of fly activity and can help pinpoint areas where flies are congregating.
Understanding the Causes of Outdoor Fly Infestations
To effectively deter flies, it’s crucial to understand what attracts them in the first place. Dana Nayduch, a USDA researcher specializing in flies, emphasizes their primary drive: “Their goal in life is to make a lot more flies. That’s it.”
Female flies are constantly searching for environments that provide food, mating opportunities, and ideal locations to lay their eggs. These locations typically offer a combination of protein sources for the adult flies and microbe-rich environments to support their developing larvae. Common sources around homes that fit this bill include:
- Unsecured Trash Cans: Food scraps, especially meat, and general waste in uncovered or poorly sealed trash cans are major attractants.
- Unattended Compost Piles: Decaying fruits, vegetables, and other organic matter in compost bins can become breeding grounds if not managed properly.
- Pet Waste: Dog feces left in the yard, particularly blow fly attractants, provide both food and breeding habitat.
- Uncleaned Garden Debris: Overripe or rotting fruits and vegetables left in the garden can attract and sustain fly populations.
- Dead Animals: Carcasses of rodents or other small animals that may die in yards or nearby wooded areas are potent attractants and breeding sites.
Karim Gharbi aptly describes an ideal fly habitat as, “It’s a nursery, a buffet, and also a wedding venue, all at the same time.” A single female fly can lay up to 500 eggs in just a few days, highlighting the rapid potential for infestation. Therefore, identifying and eliminating these food and breeding sources in your yard is the most effective long-term strategy for fly control. If the problem originates from neighboring properties, or for immediate relief before outdoor events, there are additional methods to consider.
:max_bytes(150000):strip_icc()/get-rid-of-flies-garden-getty-1023-d4121466c99c404ebdd060d80a510072.jpg)
Alt text: Close-up of a fly on a plant leaf in a garden, illustrating flies’ attraction to outdoor environments and potential food sources in gardens.
Effective Methods to Deter Flies Outside
Our experts recommend these strategies for keeping filth flies away from your outdoor living spaces:
Fly Traps
Fly traps are a highly effective and affordable solution for outdoor fly control. These traps are designed to lure flies in with attractive scents and prevent their escape. You can find various types of fly traps at hardware stores or online, ranging from ready-to-use traps pre-filled with attractants to refillable options that allow you to use your own bait, such as chicken bones or fruit scraps.
Edwin Burgess, an entomologist at the University of Florida, notes that many commercial fly traps utilize compounds like putrescine and cadaverine, which mimic the odors of decaying matter that flies find irresistible. For optimal effectiveness, place fly traps strategically around your yard, away from your immediate patio or deck area to draw flies away from your living spaces. While traps won’t eliminate every fly, they can significantly reduce fly populations in targeted areas.
Fly Tape
Fly tape is another practical and economical option, particularly useful in semi-enclosed outdoor spaces like garages, sheds, or near chicken coops. These sticky strips of tape are coated with an attractant that lures flies to land on them, trapping them. Fly tape can be discreetly placed in corners, under eaves, or near downspouts to minimize visual impact while still effectively catching flies.
Burgess explains that fly tape works because “Flies like to perch, especially on dangling things, while they rest.” Fly tape exploits this behavior, providing an attractive landing spot that turns into a trap.
Encourage Natural Predators: Spiders
Consider spiders as natural allies in your fly-deterrence efforts. Resist the urge to eliminate spiders in your yard, as they are significant predators of flies and other insects. A study highlighted the immense impact of spiders globally, estimating they consume between 400 to 800 million tons of insects and pests annually, surpassing human meat and fish consumption in protein weight.
While you might want to remove spiderwebs directly on your porch or patio for aesthetic reasons, especially if unoccupied, remember that spiders are constantly rebuilding webs and actively hunting. Allowing spiders to thrive in your yard provides continuous, natural fly control.
Introduce Parasitoid Wasps
Parasitoid wasps are tiny, ant-sized insects that are harmless to humans but deadly to flies. These beneficial insects are natural enemies of filth flies. Adult parasitoid wasps feed on pollen and nectar from flowers and do not sting or build nests, making them unobtrusive and safe for use around homes and families.
Their effectiveness lies in their parasitic lifecycle. Female parasitoid wasps seek out fly pupae (the stage between larva and adult fly) and lay their eggs directly inside. The wasp larva then develops by consuming the fly pupa, effectively eliminating the developing fly. Once mature, the parasitoid wasps emerge, mate, and continue the cycle, providing ongoing fly control.
Parasitoid wasps are particularly effective if the source of your fly problem is persistent and beyond your immediate control, such as from neighboring properties. They can be purchased online or from garden supply stores; search for “parasitoid wasps for filth fly extermination.”
Utilize Fly-Repelling Scents: Essential Oils
Certain scents can act as natural fly repellents. Essential oils, derived from plants, offer a fragrant approach to deterring flies. However, Edwin Burgess notes that essential oils can be a more expensive option compared to other methods.
Furthermore, the strong scents required to repel flies might be off-putting to some people, especially in outdoor dining or relaxation areas. “You’re talking about having those kinds of very pungent odors around you while you’re sitting on your deck,” Burgess points out. “If you’re trying to eat or sipping a cocktail or something like that, they can be off-putting to some.” If you choose to use essential oils, consider citronella, peppermint, eucalyptus, or lavender, and apply them to diffusers or cloths placed strategically around your outdoor space.
Citronella Candles: Limited Effectiveness
Citronella candles are often recommended for mosquito control, and some believe they also deter flies. While citronella candles can offer some level of fly deterrence, experts like Burgess find them less effective against flies compared to mosquitoes.
“Mosquitoes are very repelled by the smoke and odors that emanate from them,” Burgess explains. “But the little bit of smoke that those give off—flies don’t seem to mind it as much.” Citronella candles might provide marginal fly deterrence, making them “somewhat better than nothing, but not as good as they are for mosquitoes.” For fly control, prioritize other more targeted methods.
Eliminate Fly Food Sources: Key to Long-Term Control
The most fundamental and effective strategy for long-term fly control is eliminating the food sources that attract them. Dana Nayduch emphasizes, “They’re a nuisance to you because they’re looking for food or breeding habitat. And if you’re leaving out stuff that smells great to them, they’re going to just follow their nose in search of those things.”
Take these steps to mitigate food sources around your yard:
- Regularly Clean Trash Cans: Rinse out trash cans, especially outdoor bins, to remove residue and odors that attract flies. Pouring the rinse water onto pavement to dry in the sun or onto soil allows healthy soil microbes to break down any remaining organic matter and outcompete fly-attracting microbes, as suggested by Gharbi.
- Promptly Manage Pet Waste: Collect and dispose of dog poop from your yard frequently, ideally daily, to prevent blow flies from laying eggs.
- Maintain Your Garden: Clear out fallen or overripe fruits and vegetables from your garden promptly. Properly manage compost piles to minimize odors and fly attraction.
- Address Dead Animals: If you discover a dead animal on your property or nearby, arrange for its removal. Contact animal control or a professional removal service if necessary.
By diligently managing potential food and breeding sources, you significantly reduce the attractiveness of your yard to flies, leading to long-term control.
Ineffective Fly Deterrents: What to Avoid
Many commonly suggested “solutions” for fly control are ineffective and not worth your time or money, according to our experts:
:max_bytes(150000):strip_icc()/get-rid-of-flies-bug-zapper-getty-1023-345da12be8a9420e87de95e32753355d.jpg)
Alt text: A bug zapper device illuminated at night, highlighting its function as an insect-killing device, while also noting its indiscriminate nature in killing various insects, not just flies.
Fans: Flies are Strong Fliers
Using fans to blow flies away might seem like a simple solution, but it’s largely ineffective. “Flies are strong flyers,” Burgess points out. “They can travel long distances, and they can basically endure windy conditions that other types of flying insects don’t always deal with very well.” Fans may provide temporary relief in a very localized area, but flies will quickly return and are not significantly deterred by moving air.
Birds: Not Primarily Insect Eaters
Attracting more birds to your yard is often suggested as natural pest control, but it’s not a reliable method for fly control. “A lot of birds are not as insectivorous as people think they are,” says Burgess. “Most of them are foraging for other things, like seeds, fruits, and shoots on plants, to make up their omnivorous diets. Insects are not the main thing on the menu for them.” While some birds may eat flies opportunistically, relying on birds for fly control is not a practical or effective strategy.
Bats: Nocturnal Feeders
Bats are excellent mosquito predators, and installing bat houses can help control mosquito populations. However, they are not effective against flies. “Bats are nocturnal feeders,” Burgess explains. “And house flies and filth flies are not going to be flying around at night when the bats are.” Flies are active during the day, while bats hunt at night, resulting in minimal overlap and no significant fly control benefit from bats.
Bug Zappers: Indiscriminate Insect Killers
Bug zappers use UV or fluorescent light to attract insects and then electrocute them. While they kill insects, they are not a targeted solution for flies and have significant drawbacks. “The bug zapper will also kill butterflies and moths—just about any flying insect that uses light to navigate,” says Gharbi.
Given the global decline in insect diversity, indiscriminately killing insects with bug zappers is environmentally detrimental, especially when targeted solutions are available. “A fly trap will only kill flies because it usually has either organic material or it’s laced with the pheromone that the flies use to mate,” Gharbi explains. “So they are selectively attracted to that.” Fly traps are a much more targeted and ecologically responsible approach compared to bug zappers.
Vodka in Bags: An Old Wives’ Tale
The myth that vodka-filled plastic bags hung from trees repel flies is a persistent but debunked old wives’ tale. “That’s an old wives’ tale that goes way, way back,” Burgess says. “And it does not work at all. It has actually been debunked through research.” Worse, vodka might even attract fruit flies, exacerbating your pest problem. Avoid this ineffective and unsubstantiated method.
Waiting for Cold Weather: Flies Overwinter
Relying on winter to eliminate flies is a misconception. “Flies overwinter as larvae or pupae under the soil and in other protected places,” Nayduch explains. While adult fly activity decreases in cold weather, the problem is not eliminated. As soon as spring arrives and temperatures rise, overwintering flies will emerge, and the cycle will begin again. Proactive fly control measures are necessary year-round, not just seasonal.
When to Seek Professional Fly Control
Consider contacting a professional pest control company for fly control only after you’ve exhausted other methods and are still facing a significant infestation. “But also get a second opinion,” advises Gharbi. “Because sometimes the pest control companies will recommend treatments that don’t really address the root of the problem. And just spraying chemicals without addressing the root of the problem is going to ensure that you have a continued fly infestation, and the pest control company is going to have a continued source of business from you.”
Furthermore, many chemical fly control products are not registered for outdoor use, and indiscriminate chemical spraying can have negative environmental impacts. Flies that survive chemical treatments may also develop resistance, making future control even more challenging. Prioritize source reduction and targeted methods before resorting to professional chemical treatments.
Even with the best efforts, some flies are likely to be present outdoors, especially when dining outside. “Houseflies go where they need to go to reproduce and eat,” Nayduch concludes. “They are cosmopolitan—they have worldwide distribution. And so they can travel great distances if they have to.” For fly-free outdoor meals, utilize practical solutions like wire or plastic food covers for buffet-style dishes or consider using pop-up screened enclosures for patios or porches to enjoy your outdoor spaces comfortably.
