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Fish Pee and Sunshine

BSF: Compost Diversity?

Greg Vialle Sunday 16 of February, 2014
In the course of setting up my plumbing and researching bell siphon designs, I ran across some YouTube videos on black soldier fly composting systems. Since I know that BSF larvae are a commercially available food source for aquaculture, I was intrigued. A few things about BSF (courtesy Wikipedia and other sources):
  • Prevents houseflies from laying eggs in the material inhabited by BSF larvae.
  • Not usually a pest. Not attracted to human habitation or foods. As a detritivore and coprovore, the egg-bearing females are attracted to rotting food or manure (i.e., compost).
  • Black soldier flies don't fly around as much as houseflies. They are very easy to catch and relocate when they get inside a house, as they do not avoid being picked up, they are sanitary, and they do not bite or sting.
  • Reduce E. coli and Salmonella
  • Quickly reclaim would-be pollutants
  • Break down compost, create heat, increasing compost evaporation. Significant amounts are also converted to carbon dioxide respired by the grubs and microorganisms.
  • Compared to worm composting, BSF larvae are better at quickly converting "high-nutrient" waste into animal feed. Worms are better at converting high-cellulose materials into soil amendment. The activity of larvae can keep temperatures around a 100 degrees F while worms require cooler temperatures.
  • Larvae are also human edible, containing up to 42% of protein, and a lot of calcium and amino acids. In 2 weeks, a gram of black soldier fly eggs can become 2.4 kg of protein. The taste is said to be "nutty and a bit meaty."

BSF larvae composting seems to be complementary to redworm composting, in that it can process some of the wastes not usually compatible with worm composting (citrus and fatty animal waste). It also sounds like a better means to feed fish.


Most of the systems I've seen are based on wild, outdoor ovipositors. Here is the video for what I would consider a fairly convenient design:


What I like about this design (as opposed to some of the other 5gal bucket ones out there) is the transparent walls that have the educational advantage of allowing my kids to see into it, as well as reducing the need to open it. It also seems like a reasonable size for my household, to augment our worm farm. Like everything else nowadays, there is at least one website devoted to the subject. The open question for me remains how compatible they are for my climate here in Denver. If I have to maintain the entire life cycle indoors, I need to set up a relatively closed system, to maintain breeding stock.