If you live within climate zones 6 to 10, you are very likely to have a native population of black soldier flies (BSF) in your area. These local BSF are best for your conversion bin for they are adapted to your particular climate (unlike purchased ones from out of area). The BSF population within your neighborhood may be initially small and it is just be a matter of increasing their population levels over time. Or…you may already have a large population if you or your neighbors are composting. BSF love compost! Are there chickens in your area? Many chicken farmers (including backyard keepers) will have BSF breeding in any rotting pile of chicken feed or corn or in the manure pile. Basically, don’t worry about whether you have BSF in your area – you probably already do! It will be just a matter of attracting them to your bio-conversion unit.
The BSF bio-conversion unit can be a DIY or a pre-made one. I personally prefer the units produced by ProtaCulture. They are easy to use and do not look like a mad science project. If you live near Asheville, NC, please contact me if you are interested in obtaining one. I can usually provide them at a reduced rate.
Important points with raising BSF larva (grubs):
Full shade is the best placement for your unit. The grubs like it dark. Plus they produce lots of their own heat and can over heat very quickly. This is something you will need to pay particular attention to late in the summer or if you live in a warm location. My grubs overheated during August in the mountains!
Drainage from your conversion unit is very important! These grubs are aerobic meaning they love air. This species of flies is not aquatic! They do like moisture just not too much. So the material needs to stay damp/wet…not soupy…you will get the “feel” of it after a while.
Collection of mature grubs is varied. The natural tendency of the mature grubs is to move out of the waste and find somewhere to pupate. Unfortunately, many DIY units either require you to “dip” them out of the waste or the self- harvesting mechanism doesn’t always work correctly. Another reason, I prefer the premade unit.
Feeding your grubs:
Start slow with the food scraps. You really need to get the population going before you start feeding them lots of food scraps. First you need to attract them, make sure they are established, and then you can build up to the higher feeding rate. Once established, these grubs can devour food waste within 24 to 36 hours. Thus the food does not have time to rot or smell!
“Anything you eat” is the rule of thumb. They are not able to eat hard bones, shells (shellfish, nuts, or egg), fruit pits, yard waste, etc. I think you get the idea. Citrus peels can be slightly toxic to them, so limit or refrain from feeding this to your BSF. Cooked food is typically eaten faster than uncooked – especially when it comes to veggies. They do eat processed food very quickly, just remember these foods usually contain higher levels of salt. So if you plan on using your “grub tea” for the garden you need to be careful with long term salt accumulation within the garden soil.