Composting 101: Dealing with flies

My worm bin has always been on the wet side, with most of the finished compost dripping through the wide grating at the bottom of my Wriggly Wranch, which hasn't really bothered me because there are enough worms swimming around in the lower level to suggest that it hasn't become too anaerobic (lacking the oxygen worms and other organisms need to do their decomposing), but it's also been more fly-prone than usual lately, which needless to say isn't my favorite thing about composting.

With all that life going on, it was nice that we had a little composting refresher in my Permaculture class the other day to help sort things out. Here are some helpful tidbits of info, should you find yourself with a worm bin:

1. The kind of little flies or other insects that tend to come with worm composting generally have about a 14 day life cycle. So, if you ever have a serious problem, make sure to stop adding food to your bin for at least 14 days to wait out the current cycle.

2. Flies need a moist environment to lay their eggs and produce the next generation of their kind, so you want to keep your bin as dry as possible. Wetness in and of itself isn't a problem, but it provides a happy environment for fly larvae and makes your finished compost a little messier than you might like, whereas drier compost would be less likely to drip through the grate at the bottom of your bin. Other advantages of relatively dry compost are that the anaerobic liquid also being produced during the decomposition process can leak to the bottom (which is what that spout is there to release, if you have one) without contaminating your compost and that harvesting might not be quite as messy.

Some simple ways to dissuade flies from colonizing your bin include:

Adding more newspaper to the top.
Leave as much as 6" of newspaper strips over your foodscraps. For more serious fly problems, you can also lay a few sheets of whole newspaper over the top to create more of a barrier. More newspaper can also help with odor problems.

Use drier foodscraps.
Worms (and the other decomposers) love to eat the vegetables left over from making vegetable stock, but these are really wet. To dry out stock left overs, I've started leaving them out on the stove once I've poured off the stock I'll be using and allowing them to air dry or turning the heat back on under my pot to further dry the scraps out.

Always add food scraps UNDERNEATH newspaper.
The harder it is to get to food scraps, the less likely flies will discover and gorge themselves on them. Tossing your food scraps on top makes it easy for pests to find them and harder for your worms. Scraps on top will take longer to decompose, which can lead to rotting, which means bad smells and probably more flies.