Getting Rid of Pesky Mayflies for Good

Mayflies, also known as fishflies, are a common nuisance during the spring and summer months. Their large swarms can quickly take over patios, porches, and backyard spaces, disturbing homeowners trying to enjoy the warmer weather. While mayflies themselves are harmless, their sheer numbers and presence can be incredibly disruptive.

Luckily, there are ways to prevent, control, and get rid of mayflies so you can reclaim your outdoor living areas.

What Are Mayflies and Why Are They a Problem?

Mayflies, which belong to the insect order Ephemeroptera, are a type of aquatic bug that only lives for 24-48 hours as winged adults. They emerge en masse to mate and lay eggs, forming massive swarms near water sources.

While adult mayflies do not bite or sting, their swarming behavior, corpse piles, and potential to invade homes can cause major annoyances:

• Large swarms blocking doorways and entryways
• Hundreds to thousands covering surfaces in a short time
• Potential to enter cracks and crevices around windows and doors
• Build up of dead mayflies causing foul odors and slippery surfaces
• Attraction of other insects to decaying mayfly bodies

In addition to being a nuisance, mayfly swarms can also pose hazards by making surfaces slippery, clogging machinery, and even causing distraction and visibility issues for motorists if large enough.

Mayfly Lifecycle and Behavior

Mayflies have a unique lifecycle that contributes to their swarming tendencies:

• Eggs laid in freshwater sources hatch into nymphs
• Nymphs mature over weeks to months, shedding exoskeletons as they grow
• Mature nymphs rise to the water surface, shed exoskeletons, and emerge as subimago adults with wings
• Subimagos fly to land, shed exoskeletons again, and become imago adults
• Adults live only 1-2 days to mate and females to lay eggs back in the water

The short adult stage and singular focus on reproduction is why mayflies form such dense swarms. Their mating swarms concentrate around lights, especially bright white light. This attraction to light brings them closer to homes and inhabited areas, increasing nuisance potential.

Preventing Mayfly Swarms and Infestations

Stopping mayflies before they become a problem is the best line of defense. Strategically restricting access, modifying certain areas around your home, and discouraging conditions mayflies favor can significantly reduce their presence and nuisance impact.

Make Your Property Less Attractive

Mayflies gravitate toward bright lights and pale surfaces that mimic their breeding waters. Minimizing these preferred conditions cues can deter mayflies and reduce how many approach your home.

• Install warmer, yellow-toned outdoor lighting which is less attractive
• Replace white light bulbs with less attractive yellow bulbs
• Use lower wattage bulbs to reduce light brightness
• Turn off outdoor lights at night whenever possible
• Close curtains and blinds at night to block indoor light
• Paint or stain dark colors on outdoor walls and surfaces

Block Entryways and Access Points

Sealing off areas mayflies use to enter structures keeps them safely outdoors and away from living spaces.

• Install tight-fitting screens on windows and doors
• Seal cracks, crevices, and gaps in siding, eaves, and walls
• Close off openings around outdoor fixtures, vents, wiring, and pipes
• Fill hole and gaps under doors with weather stripping or sealant
• Keep doors shut rather than letting them stand open

Manage Outdoor Conditions

Making the outdoor areas and structures around your less suitable for mayflies establishes further barriers against infestations.

• Remove standing water and soggy debris
• Clear mayfly corpses, spiderwebs, and egg masses
• Clean out piled leaves, sediments, and clutter
• Maintain proper drainage from gutters and downspouts
• Eliminate or refresh stagnant ponds, fountains, and bird baths
• Divert water runoff away from homes and structures

Removing Existing Mayfly Infestations

If prevention methods fall short and mayflies make it inside or swarm outside living areas, taking action to remove them is the next step.

Physical Removal Methods

For mild infestations, physical removal may be enough to clear out the insects and their debris.

• Vacuum up live, dead, and dazed mayflies where clustered
• Sweep areas to brush mayflies out of entryways
• Use a stiff broom to dislodge clusters roosting on walls
• Spray away swarms with water via garden hose or pressure washer
• Clear piles of dead mayflies with rakes, shovels, and garbage bags

Traps and Contained Treatments

Traps take advantage of mayflies' attraction to light and contain treatments to certain areas:

• Set up insect electrocution traps with zapping light grids
• Install buckets or containers with soapy water underneath lights
• Hang sticky traps or fly paper near lights and entry points
• Apply contained sprays in storm drains, window wells, or other clustered areas

Insecticide Sprays

For extensive infestations across large outdoor areas, spraying insecticides produces thorough mayfly knockdown and mortality:

• Use pyrethrin- or pyrethroid-based aerosol sprays as targeted treatments
• Hire a professional pest control company to treat swarm hotspots
• Apply a certified insect growth regulator (IGR) to disrupt lifecycles
• Use synergized pyrethrin spray for rapid knockdown of swarms

*Always carefully follow instructions and precautions when applying insecticidal products*

Repelling Mayflies

After tackling active swarms and infestations, implementing repellent strategies helps further discourage repeat mayfly issues in the future.

Remove Attractants

Eliminating or adapting light sources which draw in mayflies reduces likelihood of re-infestation.

• Replace outdoor white bulbs with less attractive yellow bulbs
• Use the lowest wattage possible for outdoor fixtures
• Install motion sensor lighting to only activate when needed
• Turn off any unnecessary outdoor lighting at night

Use Fans, Air Screens, and Zappers

Strategically placed equipment can divert, block, or eliminate mayflies as alternative repellents.

• Set up oscillating fans near doors or Hang fly fans over entryways
• Install air curtain air screens across doorways or openings
• Employ electrified light zappers near doors and susceptible areas