New York’s 7 Most Annoying Biting Flies and What to Do About Them
February 24, 2026
If you’ve ever stepped outside on a warm summer morning in the Adirondacks, hiked a trail in the Catskills, or simply sat on your back porch on Long Island and found yourself swatting at something you can barely see — you already know the problem.
New York is home to some of the most relentless biting flies in the northeastern United States, and they don’t discriminate between hikers, farmers, beachgoers, or backyard barbecue guests. Biting flies in New York are active from late spring through early fall, with different species peaking at different times and in different habitats.
Knowing which fly is targeting you — and why — makes all the difference when it comes to protecting yourself, your family, and your pets. This guide breaks down the seven most common biting flies you’ll encounter across the state, where they live, when they’re worst, and exactly what you can do to keep them at bay.
1. Black Fly
If you spend any time near rivers or streams in upstate New York between May and June, you’ve almost certainly met the black fly (Simulium venustum). These small, hump-backed flies are notorious across the Adirondacks and Catskills, where locals sometimes refer to late spring as “black fly season” with a mixture of resignation and dark humor. They swarm in enormous numbers, crawling into ears, eyes, and the neckline of your shirt before you even realize they’re there.
Only female black flies bite, and they do so to obtain the blood protein needed for egg development. Unlike mosquitoes, they don’t inject anesthetic before feeding, which means the bite often goes unnoticed at first — but the aftermath is anything but subtle. Black fly bites cause a condition sometimes called “black fly fever,” which can include swelling, itching, headache, and in rare cases, nausea. The bites bleed more than most insect bites because black flies use a scissor-like mouthpart to cut the skin rather than pierce it.
Key Insight: Black flies breed exclusively in fast-moving, well-oxygenated water. If you’re camping or hiking near waterfalls, rapids, or rocky streams in the Adirondacks, expect heavy black fly pressure from mid-May through late June.
Black flies are most active during daylight hours, particularly in the early morning and late afternoon. They’re drawn to dark clothing, carbon dioxide, and body heat. To reduce bites, wear light-colored, tightly woven long sleeves and use a head net in heavily infested areas. DEET-based repellents offer moderate protection, though black flies are notoriously difficult to deter completely.
Permethrin-treated clothing provides an additional layer of defense for serious outdoor enthusiasts. For more on how biting flies vary by region, see how they compare to biting flies in Maine, where black fly pressure is similarly intense.
2. Deer Fly
Deer flies belong to the genus Chrysops and are among the most persistent biters you’ll encounter in New York’s wooded and wetland areas. They’re medium-sized flies with distinctively patterned wings — usually banded with dark markings — and bright, iridescent eyes that make them easier to identify than many other biting flies. You’ll find them most active from June through August, particularly near marshes, forest edges, and slow-moving water.
What makes deer flies especially maddening is their hunting strategy. They target moving objects and are attracted to motion, dark colors, and carbon dioxide. Once a deer fly locks onto you, it circles persistently, looking for an opportunity to land — usually on the head or neck. When it bites, it cuts the skin with blade-like mouthparts and laps up the pooling blood. The bites are painful and can cause significant localized swelling and itching that lasts for days.
Deer flies are also capable of transmitting tularemia (rabbit fever) in rare cases, making them more than just a nuisance. If you’re working or recreating in areas with high deer fly populations, wearing a wide-brimmed hat treated with permethrin can significantly reduce the number of successful bites. Some hikers swear by the “Deer Fly Patch” — a sticky trap worn on the back of a hat — which physically captures flies as they land. DEET remains the most effective chemical repellent for this species.
Pro Tip: Deer flies are visual hunters. Wearing light-colored clothing and a permethrin-treated hat dramatically reduces your attractiveness as a target when moving through wooded or wetland terrain in summer.
3. Horse Fly
Horse flies, classified under the genus Tabanus, are the heavyweights of New York’s biting fly world. These are large, robust insects — some species reaching nearly an inch in length — with large compound eyes and powerful, blade-like mouthparts capable of delivering a genuinely painful bite. They’re most active during the hottest months of summer, typically July and August, and are found statewide wherever livestock, deer, or large mammals are present.
Like deer flies, only female horse flies bite, and they require a blood meal to reproduce. They’re strong fliers and can pursue hosts over considerable distances. Horse flies are particularly problematic around farms, rural properties, and areas adjacent to wetlands or slow-moving water, where they breed. Their larvae develop in moist soil or aquatic environments, so proximity to ponds, marshes, and stream banks increases local populations significantly.
Horse fly bites are among the most painful of any biting insect in New York. The wound often bleeds freely after the fly leaves, and secondary infection is a real concern if the bite isn’t cleaned promptly. Horse flies are also known vectors of equine infectious anemia, making them a serious concern for horse owners across the state.
Important Note: Horse flies are largely resistant to standard insect repellents. Physical barriers — such as fine mesh screens on barn windows, fly sheets for horses, and long sleeves for people — are more effective than chemical deterrents for this species.
For those managing livestock properties, installing walk-through fly traps and using sticky tape traps around barn entrances can help reduce horse fly populations locally. If you’re curious how horse fly pressure compares elsewhere in the region, the biting flies in Wisconsin share many of the same species challenges due to similar wetland and agricultural landscapes. You might also find useful comparisons in our look at biting flies in Alabama, where horse flies are active for a much longer season.
4. Stable Fly
The stable fly (Stomoxys calcitrans) looks deceptively similar to the common house fly, which is exactly why so many people are caught off guard when it bites. Unlike house flies, stable flies have a rigid, bayonet-like proboscis that protrudes forward from the head — a key visual identifier if you look closely. Both males and females feed on blood, making stable flies unusual among biting flies and doubly problematic around livestock operations and coastal areas.
In New York, stable flies are a year-round concern in agricultural settings but peak in late summer and early fall. They’re strongly associated with decaying organic matter — rotting hay, manure, and wet straw are prime breeding sites. Along the coast, decomposing seaweed on beaches has been linked to significant stable fly outbreaks, making them a seasonal nuisance for beachgoers on Long Island as well as inland farm communities.
Stable flies typically bite the lower legs, making them particularly bothersome to people sitting outdoors or standing near livestock. The bite is sharp and immediate, unlike some other biting flies that may go unnoticed at first. Repeated biting can cause significant irritation and stress in both humans and animals.
Pro Tip: If you’re seeing fly bites on your lower legs while sitting on the beach or near a barn, stable flies are likely the culprit. Wearing light-colored socks and applying DEET to exposed lower legs can help reduce bites significantly.
Controlling stable flies requires addressing breeding sites directly. Removing or composting manure regularly, keeping bedding dry, and clearing beach wrack (seaweed) from coastal areas during peak season are the most effective long-term management strategies.
Insecticide sprays applied to resting surfaces in and around barns can supplement these efforts. For a broader look at how this species behaves in other states, check out our coverage of biting flies in Florida, where stable flies are a major coastal and agricultural issue.
5. Greenhead Fly
The greenhead fly is one of New York’s most regionally distinctive biting insects, and if you’ve ever visited the salt marshes of Long Island, the Hudson River estuary, or the coastal wetlands of Staten Island in midsummer, you know exactly what that means.
Greenheads are a species of horse fly recognizable by their large, brilliant green compound eyes, which give them their common name. They emerge in force during July and early August, turning coastal marshes into near-uninhabitable zones for unprotected visitors.
Greenheads are aggressive, fast, and persistent. Unlike some biting flies that can be waved off, greenheads seem almost immune to casual deterrence — they’ll circle back repeatedly until they find an exposed patch of skin. Their bites are painful and can cause significant swelling, particularly in individuals with sensitivities. Coastal communities on Long Island have long dealt with greenhead pressure, and some beach parks actively manage populations using box traps designed specifically for this species.
The greenhead’s life cycle is tightly tied to salt marsh habitat. Larvae develop in the moist, organic-rich soil of tidal marshes, and adults emerge over a predictable window each summer. This makes population timing relatively consistent from year to year, which at least allows you to plan accordingly. Peak greenhead activity typically runs from early July through mid-August along New York’s coastal areas.
Key Insight: Box traps — dark, box-shaped structures placed at the marsh edge — are the most effective tool for reducing greenhead fly populations in coastal areas. Several Long Island beach communities deploy these traps each summer to protect visitors.
When visiting coastal areas during greenhead season, wear light-colored clothing that covers as much skin as possible, apply DEET-based repellent to exposed areas, and try to schedule outdoor time in the early morning or evening when greenhead activity drops.
Breezy conditions also suppress their activity, so exposed, wind-swept areas of the beach tend to be more comfortable than sheltered spots near the marsh edge. You can explore similar coastal biting fly challenges in our article on biting flies in Louisiana, where marsh-associated species are equally aggressive.
6. Biting Midges / No-See-Ums
Biting midges, commonly known as no-see-ums, belong to the family Ceratopogonidae and are arguably the most frustrating biting insects in New York — not because their bites are the most dangerous, but because you often can’t see them coming. At roughly 1–3 millimeters in length, they pass easily through standard window screens and mosquito netting, making conventional barriers largely useless against them.
In New York, biting midges are most common in coastal areas, lakeshores, and wetland-adjacent communities, though they can appear wherever there’s moist soil or standing water for breeding. They’re most active at dawn and dusk, particularly on calm, humid evenings when there’s little wind to disperse them. The bites are disproportionately irritating for such a tiny insect — a cluster of no-see-um bites on the ankle or wrist can produce intense itching and red welts that last for days.
No-see-ums are a particular challenge for campers, anglers, and anyone spending evenings near water in the Adirondacks, Finger Lakes region, or Long Island’s coastal communities. Standard DEET repellents do work against them, but coverage must be thorough since the flies are small enough to find gaps in protection easily. Picaridin-based repellents are also effective and may be preferable for those who find DEET irritating to skin.
Common Mistake: Using standard mosquito netting or window screens to block no-see-ums won’t work — their tiny bodies pass right through. Look for fine-mesh “no-see-um netting” with at least 46 holes per square inch for effective protection in tents and shelters.
Wearing tightly woven fabrics and applying repellent to clothing as well as skin helps close the coverage gaps that no-see-ums exploit. Permethrin-treated gear is particularly useful for extended outdoor stays. A fan or breeze — even an electric fan on a porch — can effectively disrupt their flight and reduce biting pressure significantly, since these tiny flies are weak fliers.
For comparison, see how no-see-ums behave in warmer climates in our guide to biting flies in Texas, where they’re active for a much longer portion of the year. You might also find our broader look at insects in New York useful for understanding the full range of species sharing the state’s diverse habitats.
7. Mosquitoes
No list of New York’s biting flies would be complete without mosquitoes, and while they’re technically flies (order Diptera) rather than “biting flies” in the colloquial sense, their impact on outdoor life across the state is undeniable. The two most prevalent genera in New York are Aedes and Culex, each with distinct behaviors, peak activity windows, and public health implications that make them worth understanding separately.
Aedes mosquitoes, which include the aggressive eastern treehole mosquito and the invasive Asian tiger mosquito, are daytime biters that breed in small containers of standing water — tree holes, gutters, birdbaths, and even bottle caps.
They’re found statewide and are the primary vectors of Eastern Equine Encephalitis (EEE) and certain strains of West Nile Virus in New York. The Asian tiger mosquito (Aedes albopictus), identifiable by its bold black-and-white striped pattern, has expanded its range significantly across the New York metro area and Hudson Valley in recent years.
Culex mosquitoes, by contrast, are primarily nighttime biters and breed in larger bodies of stagnant water — storm drains, retention ponds, and neglected pools. They are the principal vectors of West Nile Virus in New York State, which the New York State Department of Health monitors closely each season through an active surveillance program. West Nile cases in New York have been reported every year since the virus first appeared in the state in 1999.
Important Note: New York State conducts annual mosquito surveillance and larviciding programs, particularly in downstate counties. Check your county health department’s website each spring for local mosquito control schedules and reported West Nile activity in your area.
Protecting yourself from mosquitoes in New York requires a layered approach. EPA-registered repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus are all effective when applied correctly. Eliminating standing water around your property — emptying birdbaths weekly, clearing clogged gutters, and covering rain barrels — removes the breeding habitat that sustains local populations. Installing or repairing window and door screens keeps them out of your home, and wearing long sleeves and pants during peak activity hours (dusk through dawn for Culex, all day for Aedes) reduces exposure considerably.
For those in the New York City metro area, the NYC Department of Health publishes spray schedules and trap data that can help you time outdoor activities to minimize exposure during high-risk periods. Upstate residents can reference the Cornell Cooperative Extension network for county-level guidance on mosquito management. You can also explore how mosquito species and management strategies differ in neighboring states by reading about biting flies in Kentucky or our guide to biting flies in Missouri.
Conclusion
Dealing with seven different species of biting flies across a single state might feel overwhelming, but most effective protection strategies overlap significantly across species. Building a consistent approach to bite prevention — rather than reacting species by species — is the most practical way to enjoy New York’s outdoors without being driven indoors.
The following strategies offer the broadest protection across New York’s biting fly species:
- Use EPA-registered repellents: DEET (20–30% concentration) remains the gold standard for broad-spectrum protection against biting flies and mosquitoes. Picaridin is an effective, less-irritating alternative. Apply to all exposed skin and reapply as directed, especially after sweating or swimming.
- Treat clothing with permethrin: Permethrin-treated clothing repels and kills biting flies on contact, providing a layer of protection that skin-applied repellents can’t match. It’s especially valuable for black flies, deer flies, and no-see-ums.
- Wear appropriate clothing: Light-colored, tightly woven fabrics that cover arms and legs reduce the skin surface available to biting flies. Dark colors attract deer flies and horse flies; avoid them in high-pressure areas.
- Time your outdoor activities: Many biting flies have predictable activity windows. Black flies and no-see-ums peak at dawn and dusk; horse flies and greenheads are most active midday in hot, sunny conditions. Adjusting your schedule reduces exposure without requiring any chemical protection.
- Use physical barriers: Fine-mesh no-see-um netting for tents and shelters, head nets in black fly territory, and screened porches all provide passive protection without repellents.
- Eliminate breeding habitat: For mosquitoes and stable flies especially, removing standing water and managing organic debris near your property directly reduces local populations.
- Exploit wind and fans: Most biting flies — especially no-see-ums and mosquitoes — are weak fliers. A steady breeze or a strategically placed fan can make an outdoor seating area dramatically more comfortable.
Pro Tip: Layering protection methods is always more effective than relying on any single strategy. Combine permethrin-treated clothing with a DEET-based repellent on exposed skin for maximum coverage against the widest range of New York’s biting flies.
New York’s biting fly season is intense but finite. Understanding which species are active when and where — and applying the right combination of protective strategies — lets you reclaim your time outdoors without surrendering the trails, beaches, and backyards that make this state worth exploring.
For a broader regional perspective, our guides to biting flies in Colorado and biting flies in Alaska offer useful comparisons for understanding how biting fly pressure shifts across different climates and landscapes. And if you’re interested in the wider world of New York’s insects beyond the biters, our overview of insects found in New York is a great place to continue exploring.