When you are trying to enjoy your patio, nothing ruins a beautiful afternoon more than a swarm of these noxious pests landing on your arms or face or invading the plate of tapas and glass of lemonade at your elbow. Short of spraying yourself and your surroundings with nasty-smelling chemicals, there are several ways to discourage flies from using your patio as their own private cocktail lounge.
Police the Area
To eliminate flies, you must eliminate the places where they breed. Flies are attracted to moisture and breed in decaying meat and vegetation. Make sure that trash cans have tight-fitting lids and move them away from the patio. Likewise, situate your compost heap away from the patio, and cover food waste with lawn clippings or other dry matter. Promptly remove animal feces, dead birds and dead animals from your yard. Houseflies can complete a breeding cycle in seven days, so you should remove pet waste and other decaying matter at least twice weekly until the infestation is under control.
Groom the Yard
Because flies need moisture and rotting material to breed, landscaping and garden maintenance are crucial to keeping flies away from your patio. Keep grass trimmed, and trim trees and bushes. Rake leaves and mulch or compost them. Remove any standing water, including that in planters. According to the University of Florida's Department of Entomology and Nematology, "Straw is one of the best fly-breeding materials." Keep this fact in mind when decorating for holidays like Halloween, and place straw bales well away from your patio.
Flies are repelled by a number of natural substances that you can make use of around your patio. Many torches, candles and other decorative items use citronella oil to repel insects. You can also decorate with plants containing citronella oil. Plants in the Cymbopogon genus, called lemon grasses, have insect-repelling properties. Three common varieties are C. nardus, C. winterianus and C. citratus. The attractive and pleasantly aromatic Pelargonium citrosum is marketed as "mosquito plant," "citronella plant" or "citronella geranium," but there is disagreement over whether the plant truly repels insects.
Fly traps can be purchased or made easily at home. Most consist of a bait bag or bottle covered with an inverted cone-shaped lid. Attracted by the bait, flies enter through an opening in the tip of the cone and are unable to find the exit once they have eaten. Fly paper strips can also be used outdoors, but they may trap beneficial insects as well as pests. Traps using ultraviolet light, commonly known as "bug zappers," can also be effective in reducing the adult fly population around the patio.
You may have heard of someone hanging a bag of water near entrances or outdoor gathering places to repel flies. Sometimes the bag contains a copper penny or small dark marble. There are two theories about this practice. The first is that the movement of the water refracts the light in a way that repels flies. The second is that the bag of water, especially if it has a dark object in it, scares flies away because it resembles a spider in its web. Both theories are unproven and should not be relied upon.