*I split this off from Clint's thread. BW, if you want to make changes to how I did it for the sake of consistency please feel free.

Looking forward to the pictures Clint. I've never used only coffee grounds to attract black soldier flies although I know the larvae are very attracted to them over many other types of waste. If I was to try using only coffee I would probably keep it very wet and try to get some fermentation going. Has anyone else ever tried coffee only?

Yep! It works! Lots of cellulose in it though, and a diet of only coffee grounds will cause the bin to fill with residue much faster than a more varied diet will. You may need to mist with a hand sprayer to keep the grounds moist during low humidity conditions. The cool thing about coffee is that it doesn't smell bad, resists becoming aerobic, and can be had by the bucketload for free from any Starbucks and many other local coffee shops.

I just can't imagine that old coffee grounds have enough nutritional value that black soldier fly larvae can thrive on it. It makes me wonder if the grounds are a good medium for bacterial growth and that's what the BSF benefit from.

That could be the case, Jerry. The BSF in this video were fed almost exclusively on coffee grounds with only occasional kitchen scraps added. They thrived, but the bin got full of coffee grounds in just a couple of months.

Just the wood bin in this vid was fed coffee. The Biopod and trash barrel bins got soured sweet feed, dog turds and kitchen garbage.

I wonder if you could stop adding the coffee grounds or other waste when the unit is full and then somehow feed the bacteria that may be living in the coffee. For example, would adding some type of syrup feed the bacteria, eliminating the need to add bulk food waste entirely? I don't want to promote using non-waste to feed BSF, but I'm curious about this. Perhaps one could find a source of liquid food waste to accomplish this such as spoiled juice or syrup...