A few weeks ago I put up a compost bin in my garden, similar to this one (bottomless and placed directly onto the soil). Soon after I began to use it, I noticed swarms of fruit flies inside.
The first thing I added to my compost was shrub and other plant clippings. Other than that, it gets mostly bad apples from my apple tree, as well as fruit and vegetable scraps (including leftovers from the apples I process), some egg shells (crushed), spent coffee grinds and occasionally a piece of stale bread. I have someone to mow my lawn and take out the clippings, so they don’t go on the compost. There may be leaves in fall, but that will take another month or two. Other than these things, I do not add anything that has been cooked, marinated, fermented or treated with pesticides, and make sure all fruit/vegetable scraps are domestic
Obviously, rotten apples will attract fruit flies but I have to dispose of the apples somehow, and would rather return the nutrients they contain to the soil. So I am looking for ways to contain the fruit flies.
Since I noticed the flies, I have added some compost starter (microorganisms to speed up the decomposition). I also started mixing in finely shredded cardboard and small wood chips in order to balance out the carbon-nitrogen ratio as well as moisture. I also tried sprinkling some lime on top, which one source recommended specifically against fruit flies.
There are still plenty of flies, but I only started the countermeasures recently, so results may not yet be visible.
As for climate conditions, I live in the northeastern EU, and we are experiencing a warm summer with daytime temperatures frequently around 30°C.
Can I reasonably expect the countermeasures I tried to help me get rid of the fruit flies in my compost? If not – short of disposing of the entire compost and starting over from scratch, what gives?