Fruit flies are an unpleasant, yet common pest around compost bins. Fruit flies come to feast on the green ingredients that gardeners place in compost bins. These green ingredients include a variety of kitchen scraps. While the fruit flies will not damage or bring harm to the bins, many gardeners wish to reduce or eliminate them. Try changing the ratio of brown ingredients to green ingredients to reduce fruit flies in a compost bin.
Mix the materials in the compost bin with a garden spade. While mixing, assess the ratio of brown ingredients to green ingredients. The recommended ratio is at least 1/2 of the compost ingredients to be brown, with up to 75 percent brown ingredients acceptable.
Add brown ingredients to the top of the compost bin. For best results, always keep the top layer as a brown-ingredient layer. Routinely placing green ingredients on the top of the compost bin and leaving it uncovered will attract fruit flies. Add up to 12 inches of brown ingredients to the top compost layer every time green ingredients are added.
Mix continuously and add brown ingredients every time green ingredients are added. If additional brown ingredients are not available to add to the top, mix the green ingredients in with a garden spade immediately after adding them.