QUESTION: How do I get rid of flies in my compost pile? My wife doesn’t want to use it at all because she doesn’t like bugs. Robert P
ANSWER: Insects hovering around your compost pile aren’t a cause for concern—in fact, flies and other bugs will actually help the microbes in your compost break down the ingredients. However, you shouldn’t see flies around your compost if you’re maintaining a two-to-one ratio of “brown” carbon-rich and “green” nitrogen-rich materials, making sure to always finish by adding a layer of dry “brown” ingredients to cover any food scraps. You’ll normally see flies buzzing around your compost pile if you’ve been adding lots of fruit to the materials recently.
You can continue adding fruit without attracting lots of insects by tucking the fruit (and any foods that you add to the compost) underneath the top layer so it’s not sitting right on the surface of the pile. Burying food scraps in the compost heap a bit will prevent flies from being attracted to the area as well as making sure you don’t entice larger pests, like rodents and other animals, to start visiting your compost bin.
If burying your “green” ingredients doesn’t deter insects from your compost, you can continue adding more and more “brown” carbon-rich ingredients, abstaining from adding any more “green” nitrogen-heavy materials, to cut off the insects’ food source until they disappear.
Some gardeners report that they control flies near their compost by turning and stirring the compost on a regular basis to aerate it. Ideally, you should be turning your compost every few weeks to keep oxygen available for the microbes and make sure the compost is completed as efficiently as possible. When you’re trying to discourage flies, you might turn your compost daily or every few days for a while until the infestation abates.
If that trick doesn’t work, you can get a little more aggressive and kill any flies in the compost heap by splashing boiling water onto the compost itself. (Do this when it’s time to add water to your compost anyway to prevent the anti-fly treatment from getting your moisture level out of balance.) The heat from the boiling water will kill both adult flies and their larvae, if any are present.
Finally, there are lots of reasons to use a lid with your compost, and deflecting insects and other pests is definitely one of them. (A lid also allows you to manage the moisture level and temperature of your compost, ensures the finished product will be ready quicker, contains any unpleasant odors, lets you keep making compost all year round, and protects the completed compost when it’s finished decomposing to prevent it from losing potency.) If you have a lid on your compost bin, keep it closed to keep insects at bay. If you don’t have a lid, consider adding one for the benefit of fending off pests and all the other advantages as well.