Fly Bye! Plus Fly & Mosquito Spray GallonFly Bye! Plus is a totally unique spray that works on a molecular level that provides ultimate protection from flies, gnats and mosquitos. By utilizing revolutionary soy based technology, we have created a highly effective pesticide free spray. Here is how it works: When a fly comes near Fly Bye! Plus it will actually feel a molecular change in its exoskeleton. As a survival device the fly will move away from the area that has been sprayed. Fly Bye!