Go to a super walmart(assuming they are all the same which I'm sure they are!).. buy mosquito dunks found in the garden area($10 for 6 "dunks"), then go to the area called "paper goods and chemicals", find some fly strips for another $2.
Solved my issue in a week, search for "mosquito dunks" for other discussions on what exactly to do. But basically you smash a mosquito dunk, mix it with water, feed it to your plants. And hang a few fly strips in your area to catch the flying ones.