Monday, October 4, 2010
A Confederacy of Worms
The first time I encountered solider fly larvae in my compost bin it was as a slowly heaving mass of damp leaves. The whole surface of the bin was creepily undulating up and down. When I used a trowel to push aside the thin layer of leaves, uncovering the recently added kitchen scraps, I saw the huge, whitish, maggoty creatures pictured above. Ewwww! Backing slowly away from the bin with a sick feeling in my stomach, I ran into the house and googled "huge maggots in compost!!!!"
That's how I found out about BSF, the black soldier fly, a great friend to lazy composters everywhere, we folks who never turn the pile, just add new layers and let it sit. Now, instead of recoiling in horror, I gaze fondly on the hard-working worms and urge them on.
BSF, you are my BFF.
The black soldier fly is an attractive large flying insect that looks more like a wasp than a fly. It has no mouth parts and lives briefly in order to mate and lay eggs. It does not bite, swarm, come into houses, or carry disease. The eggs are laid in wet, organic matter in the first stages of decomposition -- such as the layer of kitchen scraps in my compost bin.
The eggs hatch in just a few days into ravenously hungry larvae that start chewing their way through any nice juicy stuff they can find. They work so fast and wiggle around so much, aerating the pile where they are working, that there is no time for nasty smelling bacteria to get a foothold and create bad smells which attract the less desirable kinds of flies.
What's not to like? No smells, no flies, and very fast breakdown of organic matter, including materials usually not recommended for compost piles, such as dairy products.
They will eat anything, including manure, sewage, roadkill, etc., and are being studied for use in municipal waste systems. Although the thought of acres of undulating worms going after a city's worth of discarded organic matter is a bit nightmarish, it doesn't diminish my admiration for these first responders of Mother Nature's breakdown team.
When the larvae are ready to pupate, they crawl away from their feeding grounds, leaving behind a dark residue that is just right for the next set of responders.
Red wiggler worms like their organic matter a bit more aged than the greedy BSF larvae. When I see masses of red worms in my bin, I know the breakdown process has moved into the next phase. When the numbers decrease then it's time to add the compost to the garden beds. If I'm impatient to add some fertility ASAP I can use the compost at the red worm stage, adding some extra organic nitrogen to make up for the nitrogen needed to fuel humus making.
When the garden variety earthworms appear, it's a signal that the compost has now become soil. I have never seen earthworms in the compost bin, only in the garden. These worms, honored by Darwin for their soil building capacity, go after the tiny broken down bits of remaining organic matter and transform them into the castings that nourish good green growth.
This confederacy of worms works together to produce the rich medium needed for continuous vegetable production in our backyard.