Add 1 teaspoon of sugar and stir. Once the yeast is activated and starts to foam, cover the jar top tightly with plastic wrap try to keep the surface wrinkle free, secure with a rubber band. Make a small hole in the top so they can find their way in, most will be unable to get out. Tips. If you have an especially heavy infestation, set out a trap in a small room with the light left on overnight. Although they are most active during the day, they will be attracted to the light and make their way to the room and their tempting trap bait. Once it seems youve gotten rid of them, you may notice a fresh batch flying aroundthese are likely those that have hatched from the eggs of the previous infestation the gestation period is about 7 to 1. Repeat the cleaning process and lay out the traps until theres no recurrence. This is why its important to find all their food sources, they lay eggs on the food that will hatch later. How To Keep Flies Away Outside© 2017