A trapping method homeowners can use, which does not involve the use of pesticides, is called the “Yellow Fly Sticky Trap”. Basically it is a beach ball, (milk jugs work just as well and are easier to hang) painted black and coated with a sticky substance. The sticky substance is called Tangle-Trap and comes in a spray or liquid applicator. It can be found at local Hardware stores.
These devices are hung from a tree limb using string, in a shaded area, about 4 feet above the ground. Movement of the ball by the wind attracts the flies, thinking it is an animal, they land, get stuck, and die on the ball. Several of these balls will reduce the local adult populations.
You can also create your own “ball” using a milk jug, spray paint it a dark color and apply a sticky substance.