Horseflies are aggressive, biting pests that can quickly ruin outdoor relaxation, especially around swimming pools. These persistent insects are known for their painful bites and are a significant nuisance during warm, sunny months. Understanding the factors that draw them to your pool area is the first step in implementing effective, pool-safe control measures. This guide provides practical strategies for immediate removal and long-term prevention to help restore your peaceful poolside environment.
Identifying Why Horseflies Target Pool Areas
Horseflies rely on visual cues to locate females seeking a blood meal. The shiny, reflective surface of pool water creates a strong visual lure, mimicking a large body of water or the reflective coat of an animal. This visual attraction brings the flies into the immediate vicinity of your swimming area.
Once near the pool, horseflies detect signals that confirm the presence of a host. They are strongly attracted to the body heat and carbon dioxide (CO2) that humans and pets naturally emit. The warmth and movement of swimmers further intensifies this attraction, simulating the presence of a large, warm-blooded mammal.
Horseflies do not typically breed directly in chlorinated pool water. However, they require moist, damp earth or standing water nearby to lay their eggs. The larvae develop in saturated environments, such as muddy areas, marshy ground, or long, wet grass surrounding the pool deck.
Active Trapping and Immediate Removal Methods
The most effective and pool-safe approach involves targeted, physical trapping that exploits their natural behavior. Specialized horsefly traps mimic the thermal and visual signature of a host. These traps feature a large, dark ball that absorbs solar radiation, causing it to heat up significantly.
The biting female horsefly is attracted to the resulting infrared heat and dark color, landing on the ball in an attempt to feed. When she is unsuccessful, her natural escape instinct is triggered, causing her to fly vertically upward. A conical structure above the ball guides the fly into a collection chamber where she becomes trapped.
For immediate, localized control, non-toxic sticky traps can be used, though they are less selective than thermal traps. These traps, coated with a strong adhesive, can be hung from nearby trees or posts to catch adult flies in flight. Place these traps away from the main swimming area to prevent accidental contact by people or pets.
Physical removal of individual flies can also be done with a skimmer net, particularly when a fly lands on the water’s surface. Chemical sprays are generally discouraged near a pool, as they can contaminate the water and are less effective. Focus on using physical traps strategically along the flies’ likely flight path between breeding grounds and the sunny pool area. These traps require no electricity or chemicals, making them a safe choice for a busy pool environment.
Long-Term Environmental Prevention Strategies
Long-term prevention requires modifying the environment around your pool to make it less appealing for both feeding and breeding. The most important step is to eliminate sources of standing water or excessively damp earth near the pool area. This includes regularly checking and draining water that collects on pool covers, in empty buckets, clogged drains, or from leaky hoses, as these provide ideal breeding sites for horsefly larvae.
Managing the surrounding landscape is an effective preventative measure. Horseflies often rest in tall, dense vegetation, which provides shade and moisture. Regularly mowing the grass and trimming back overgrown shrubs around the pool perimeter reduces these resting spots.
Introducing air movement can help deter horseflies because they are relatively weak fliers in strong air currents. Positioning oscillating outdoor fans near seating or lounging areas creates a pocket of moving air that makes it difficult for the flies to land on people. Ensure that organic debris and waste are removed promptly from the pool deck and surrounding yard.