Here’s a fly whose larvae will eat just about any thing…raw meat, cooked meat, dead animals, manure, food scraps, fermented grain, coffee grounds, old fish, rotten potatoes ,onions citrus skins restaurant leftovers with salt and alcohol..anything . The female bearing eggs is attracted to such putrescent waste . She will lay her tiny white eggs in dark sheltered places above the waste so that the larvae will eventually fall into it and start eating….voraciously. An amazing 15 kgs of putrescent waste per square meter of feeding area is processed per day by the larvae. The grubs tuck right in (in contrast to compost worms which really eat the bacteria which come to feed on the waste) therefore there is no smell generated in this waste disposal system. A BIG PLUS is that BSF larvae have a distinctive but not unpleasant smell to humans which drives away house fly and fruit fly.
Best of all the larvae are self harvesting for fish or chook food, because at the prepupal stage they migrate out of the waste . By now they have converted 95% of the waste into their own bodies which are by weight around 42 % protein and about 30% fat…..plus they store high levels of calcium for future pupation. You couldn’t ask for a finer fish or chicken food! As most farmers know, protein is the expensive part of any feed ration and the use of cheap genetically engineered soy protein is ubiquitous.
Woodshavings placed in this harvesting container make a soft landing place for the grubs, who are happy to bury into it, as they naturally would bury themselves in the dirt to pupate….and emerge later as adult flies. The adults only live 4 or 5 days. They mate, lay eggs and die. They don’t sting, spread disease or enter houses much so don’t bother humans in any way. These lovely flies could be dealing with our food waste at generation point, negating the need for the collection, transport , and decay in landfill which currently generates large volumes of green house gases.PS: One proviso is that these BSF grubs, and indeed composting worms, are bio accumulators, meaning if the feedstock is contaminated with heavy metals like mercury, cadmium or lead, the grubs would not be suitable to feed your fish or chooks, and if you did be aware that the end consumer…the top of the food chain creature ( maybe you) …would get a heavy dose of heavy metal. So once again we see the value of organic systems.
Hot composting and worm farms are excellent ways of cleansing organic matter of pathogens such as parasitical worm eggs and e coli bacteria. This is particularly important when dealing with pig, human, dog and cat manure as we share the ability to host some of these pathogens. I have not yet noticed any studies on this aspect of the Black Soldier Fly waste disposal system, but the BSF larvae residue, which s 95% less volume than the original waste, makes an ideal substrate for composting worms in any case. If dealing with piggery waste I would definitely run the residue through a worm farm before application on vegetables, to be doubly sure of saftey.