The presence of insects can quickly disrupt the enjoyment of an outdoor space, particularly during the evening hours. Many common flying insects, such as moths, gnats, and certain beetles, become highly active after sunset, often congregating near human activity. This increase in nighttime activity is often a response to the artificial light sources that illuminate patios and decks. Understanding the mechanisms that draw insects into your vicinity is the first step toward effective management and control.
Controlling Outdoor Lighting to Reduce Attraction
The intense congregation of flying insects around light sources is a behavioral phenomenon known as positive phototaxis. Nocturnal insects use natural light sources, like the moon and stars, for navigation; artificial lights confuse this system, causing them to fly directly toward the bulb. The attraction is strongest with short-wavelength light, including blue, violet, and ultraviolet (UV) light, typically found in bright white or “cool” sources.
Modifying your outdoor lighting is a highly effective, passive strategy to minimize the influx of insects. Insects are less attracted to light with longer wavelengths, which fall into the yellow, amber, or orange spectrum. Replacing standard bulbs with warm-colored LED lights or dedicated yellow “bug lights” significantly reduces the number of pests drawn to your gathering areas. These warmer lights provide necessary illumination without emitting the UV-rich light that acts as a beacon.
Strategic placement is also important, even when using warm-colored bulbs. Directing lights downward, rather than outward, reduces the visible light cone that attracts insects from a distance. Placing a low-wattage, warm-colored light source away from the main seating area can serve as a decoy, drawing phototactic insects away from people. Utilizing motion sensors on perimeter lights can also limit light exposure, keeping the area dark until illumination is genuinely needed.
Active Repellent and Trapping Strategies
Personal Repellents
When insects are already present, active measures must be employed to deter them from immediate contact. Personal skin and clothing repellents offer the most direct form of protection. The most widely used active ingredients are DEET, Picaridin, and Oil of Lemon Eucalyptus (OLE).
DEET is a highly effective repellent, with concentrations between 10% and 35% providing protection against mosquitoes and ticks for several hours. Picaridin is an alternative that is nearly odorless, non-greasy, and does not damage plastics. It offers comparable protection against mosquitoes and often better results against biting flies. OLE provides plant-derived protection similar to lower-concentration DEET products, though it requires more frequent reapplication.
Area Protection
Area repellents can supplement personal protection. Devices that release a vaporized repellent like allethrin create a temporary, localized shield. Citronella candles and torches are commonly used, but their protective area is limited and easily disrupted by wind. Outdoor fans create a high-speed air zone that mosquitoes and other weaker-flying insects struggle to penetrate, providing a localized, non-chemical defense.
Ineffectiveness of Bug Zappers
Bug zappers that use UV light are generally ineffective against biting insects like mosquitoes. Mosquitoes locate hosts by sensing carbon dioxide and body heat, not UV light. These devices overwhelmingly kill beneficial, non-biting insects like moths and beetles. Bug zappers are a poor investment for mosquito control and can harm the local ecosystem.
Eliminating Breeding Sites and Hiding Places
A long-term strategy for reducing the number of nighttime pests involves targeting their breeding and resting habitats. Most biting insects, particularly mosquitoes, require stagnant water to complete their life cycle. Female mosquitoes can lay hundreds of eggs in standing water, making it imperative to eliminate every potential source.
Regularly empty and clean containers that can hold water at least once a week. Items like old tires or tarps that collect rainwater must be removed or stored properly to prevent pooling. Ensure that rain gutters are clear of debris, as clogged gutters can hold enough water to become significant breeding grounds. Potential sources include:
- Bird baths
- Pet bowls
- Flower pot saucers
- Unused buckets
For permanent water features like decorative ponds, consider adding mosquito larvicides, often referred to as mosquito “dunks,” which contain the naturally occurring bacterium Bacillus thuringiensis israelensis (Bti). This bacterium specifically targets mosquito larvae while being safe for humans, pets, and wildlife. Swimming pools must be properly chlorinated and circulated, as mosquitoes cannot breed in moving or treated water.
Managing vegetation also reduces the daytime resting places for many nocturnal insects. Mosquitoes and other pests often hide in tall grass, weeds, and dense shrubs to rest and escape the sun. Keeping grass mowed short and trimming back overgrown landscaping limits these sheltered areas, reducing the resident population that emerges once the sun sets. Finally, sealing any cracks in patios, decks, or foundations can eliminate dark, moist crevices where insects may harbor during the day.