The Walden Effect: Farming, simple living, permaculture, and invention.

Black soldier flies in the composting toilet


I finished cleaning out the 2014 humanure this week. In the process, the metal that was covering one side of the 2015 bin fell away and revealed this:

Black soldier fly compost

The finding was even more thrilling than this morning's excitement --- watching heat rise off my biggest compost pile. (Yes, I do get quite a kick out of the simple things in life.) Can you tell what's going on?

If you guessed that black-soldier-fly larvae moved into our composting toilet, you were right! We'd had hints of this invasion earlier in the year, but this was the final confirmation of the symbiosis.

Black-soldier-fly binWhat had we seen earlier? First, Mark noticed that if he shone a light down the hole at night, the excrement writhed with the motion of little grubs. (I can't think why he never took a picture....) Second, I kept putting off changing over to a new hole because the 2015 humanure bin never seemed to fill up. Either we weren't using the bathroom as much as we did in previous years (unlikely), or something was digesting our waste as fast as we dropped it down the hole.

I suspect the new addition to our composting-toilet ecosystem began when we bought black-soldier-fly eggs to seed our compost bin in 2014. The insects built up quite a population over the course of the summer and fall, but I wasn't able to get the flies to recolonize the bin this year. (Admittedly, I didn't try very hard.) Looks like they found a place they liked even better.

If you want to read more about how to incorporate composting toilets and black soldier flies into your homestead, you can check out The Ultimate Guide to Soil. Preorder now and the book will show up on your doorstep right around black-soldier-fly time in 2016. I hope you enjoy it as much as I enjoyed experimenting and writing it!

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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Thank you for NOT posting a picture of the toilet excrement with the black soldier flies. (yuck!)
Comment by NaYan Thu Dec 17 08:57:50 2015
Interesting! The critters are benefitting from your composting efforts as well as you. The plants get fertilized and it circles back around. Thank you for being brave enough to share what isn't always PC. :)
Comment by Karen Thu Dec 17 16:57:55 2015

Good discovery. I think colonising a composting toilet with BSF or compost worms (vermiculture) is a great idea. And speeds up the process a lot. I prefer to divert all urine elsewhere (diluted 1:10 onto the garden) Could you use these BSF for chicken feed ?

Comment by Jeff Thu Dec 17 18:34:57 2015

What a great idea. One day, perhaps all toilets will be made this way instead off human waste being pumped into out oceans and seas. Your article was both informative and interesting. Thank you for posting.

Comment by Diane Wed Aug 10 03:16:29 2016

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