For serious composters, the black soldier fly (BSF), hermetia illucens, is a miracle insect. The BSF larvae (grubs) love putrid wastes, and are highly efficient at composting them. Grubs can reduce the mass of waste by 95%, leaving a fine compost behind. They don’t like competition, so they give off a distinctive odor to repel other flies. Adult BSF don’t eat these wastes, so they won’t be bothering you at the next backyard BBQ.
Once the grubs are ready to pupate, they climb out of the compost bin (as long as the ramp is 30-45 degrees), and drop themselves into a bucket, a meal fit for any number of small livestock, like chickens, fish, lizards, quail, and even pigs. They’ll convert 5 pounds of waste into 1 pound of high protein grubs, and they’ll do it faster than you would believe. BSF larvae like a nice, quiet place get their grub on, so we made them a bin in the shade. These guys help us process animal manures and some of the “trickier” wastes around the homestead.
55 gallon food grade plastic barrel
6 ft 1×8 lumber
8 ft 1×2 lumber
12” corner molding
6 ft x 3 ft sheet metal
1 1/2” wood screws
3/4” wood screws
1 1/2” 45 degree PVC elbow
Short piece of 1 1/2” PVC pipe
1 Gallon collection bucket with lid
Gravel and loose bedding (sawdust, chopped straw, shredded paper, etc)
1 ft by 1ft cardboard
Other flies may inhabit your bin until your BSF population gets going. It helps to keep a cover material of chopped straw on top of the compost to prevent these other flies. Once your colony gets going, you can increase the amount of waste added. The barrel should be able to process up to 10 pounds of waste a day at maximum grub occupancy.
Initially, it is best to let the grubs pupate to increase the population of egg-laying females in your area. Once your bin has been running for while, and there are eggs in the cardboard strips, you may start harvesting your grubs for your animals. Set up a collection bucket at the drop pipe. The bucket should have a lid, and some bedding, like sawdust to keep the harvested grubs happy. Collect the grubs every day and give them to your animals.