Our compost initiative has been very active lately as contributions from community partners have increased. This is a great relationship for both VISTA and our partners as it expands quality compost production and improves community sustainability.
As compost contributions have grown, so has the fly population around the compost bins. Flies can be both a help and a hindrance. One fly type, the Black Soldier, Hermetia illucens (Linnaeus), is attracted to our compost and are quite welcome. Both the fly and its larvae are voracious reducers of all kinds of organic waste; they don't bother food that isn't rotten, they are not known as disease vectors and, despite looking like a small wasp, they don't sting or bite. Our compost system is built to take advantage of this naturally occurring ally.
Nonetheless, we don't want this fly bonanza to get too large. This is one reason you see full compost piles topped with several inches of leaves or mulch. This topping is an insulating biofilter that discourages some flies, absorbs odors and retains heat.
These reasons also are why kitchen and garden waste going into a collection pile should be visually covered with leaves. Not only do leaves add valuable dry carbon to the usually wet nitrogen-rich waste, they also act as a small biofilter when added on top of the food consistent with the top layer the committee adds to the full piles.
As a rule of thumb, cover your compost contribution with leaves until you cannot see the scraps. This does not prevent flies completely, and again we want some of their help, but it does help to keep their population from booming.
As always, the Compost Committee welcomes your help. If you see something amiss or problematic, bring it to our attention. If you have a question, fire away. If you want to learn more, come join us on a work day - it's still bright and early every Thursday.