Our primary goal is to find out if raising Black Soldier Flies larva (BSFL, Hermetia illucens) is feasible for small farmers during cold upstate NY winters. Our secondary goal is to find out the ratio of pounds of larva to pounds of feed to pounds produced. Larva are fed food waste from on-site farm activity and kitchen. BSFL are an ideal feed for fish, chickens, and pigs because they are 42% protein, develop quickly, and do not infest human spaces, or carry disease.
We bought in a 5000 larva to start a colony, and are using an existing heated greenhouse to raise the larva in plastic bins. The larva eat and grow inside the bins. When they are ready to mature into flies the larva instinctively want to crawl out of the wet habitat into a dry habitat. At this point they crawl out of the bin on a ramp and drop into a bucket for collection. The larva is then weighed on a weekly basis and fed to on-site tilapia, with some saved for breeding.
Our original bin design used 55-gallon drums turned sideways, with a hole in the top for food to go in, and a slit in the side for a ramp to come out. We chose the drums because they are inexpensive and easily available for most small farmers. However, this design proved to be an inefficient use of space, lack drainage for the copious amount of compost tea, and lack easy access to the ramp. However, the 55-gallon drums did work effectively for raising the larva.
Our second design uses plastic storage containers purchased at Lowes. Each bin is tilted with a slit at the bottom for compost tea drainage and a slit at the top for larval crawl out with a catchment at both ends. This system is definitely working more smoothly. But, since we began in late October during cooler weather it is taking a longer to establish the new bins and we had to make adjustments to accommodate the colder temperature (see Wintering Over).
BSFL eat a wide variety of food scrapes, but appear to prefer some foods to others. High-nutrient foods are consumed first, especially peppers, melons, and squashes. The larva are not as good at converting high-cellulose material like cornhusks, leaves, and plant material (Redworms definitely have the upper hand in that field). Occasionally the bins are too wet, from moist foods or a inactive colony. Absorbent materials like woodchips are added to balance the moisture content.