The Black Soldier Fly Grub is Compost King
One of my gorgeous Black Soldier Fly grubs. A face only a mother could love.
*Disclaimer* If you are squeamish, or if you're currently eating, you might want to stop reading now. But I hope you don't, because this is really fascinating stuff.
As I mentioned in this post about being a bit of a mad scientist, I started teaching myself how to compost kitchen and garden scraps this spring. And if you didn't believe me about being a mad scientist then, well, you certainly will by the end of this post.
Since I live in a loft, I'm composting on my balcony, using a couple of $5 buckets from the Home Depot. The conditions aren't ideal, but with a little know-how and determination, you can accomplish almost anything.
I read a lot about composting before getting started. And, a few weeks into the process, after seeing too many houseflies around my buckets, and wanting to get out in front of any problems, I started to research the real possibility of ending up with maggots in my compost, and what I might do about it.
During my research, though, I discovered something extraordinary, this article in the San Francisco Chronicle called, Yucky but useful: Maggots make compost. Now despite its scandalous title, the article isn't actually about housefly maggots but about Black Soldier Fly larvae, which are generally referred to by the less sensational word: grub.
Before I get to my story, and before you tune me out as a crazy person, let me tell you some of the brilliant and fabulous facts about Black Soldier Fly grubs, which I gleaned from several sources on the Web, including this excerpt from this excellent page:
“After seven years of research, ESR developed and patented a unique bioconversion process that effects a 95% reduction in the weight and volume of food waste within a matter of just a few hours. This process requires no energy, no electricity, no chemicals, not even water. It is totally self-contained and does not emit a drop of effluent, and aside from a small amount of carbon dioxide, it does not produce methane or any other greenhouse gases.”
- Black Soldier Flies are indigenous to all of the Americas, from Argentina to Boston and Seattle.
- Black Soldier Flies are not attracted to human homes, and do not spread disease.
- The actively feeding BSF grub secretes a natural fly repellant, aggressively competes with filth-bearing flies, and blocks their proliferation.
- A thriving grub bin can reduce kitchen & restaurant waste by 95%, meaning 100 lbs of food scrap will produce 5 lbs of soil amendment and 20 lbs of BSF larvae, which can be used as animal feed.
- BSF eggs hatch within 102 to 105 hours and reach maturity in 2 weeks, though they can extend their life cycle to 6 months in conditions of stress, which is partly why they’re so useful in waste removal.
- BSF grubs will convert anything to compost, even meat and animal droppings.
- After they leave the compost, BSF grubs make excellent feed for chickens, fish, frogs, or even songbirds.
My Story
I had built the Black Soldier Fly up in my mind so much that I couldn't imagine lucking out enough to see one. So, when I looked out at my compost one day and spied one down there, crawling around, I felt like I had won the lottery. I jumped for joy. They were real, these mythical creatures, and one was actually on my balcony and in my compost! After the initial thrill, I stopped moving and breathing, lest, even through the sliding glass door, I might frighten it away.
After marveling at it for ages, I finally left, hoping it was true that the solitary mission of an adult Black Soldier Fly is to procreate and lay eggs.
A few days later, when I went to turn my bins, I hadn't exactly forgotten about the fly, but I didn't expect to get so lucky. But, sure enough, there was something in the bin where I'd seen the fly. I started to get excited, but I couldn't tell if these were BSF grubs. The wriggly little monsters in my bin were small and cream-colored, resembling housefly maggots far too much for my taste.
Honestly, I wasn't sure how to feel, whether to be in raptures or grossed out. So, I opted to go for wary yet optimistic, and in an act of sheer bravery, I decided to stop turning the pile and leave the shudder-inducing "maggots" to their own devices.
Happily, Fortune favors the brave.
The first clue I had that I was on the right track was how quickly my compost began to diminish. All the articles say that BSF grubs eat like crazy, but I was putting loads of scraps in that one bucket, watermelon rinds, a dozen juiced lemons, potato peels, half an old cabbage, and on and on, and the pile, I noticed, never got any bigger. Whatever they were, those maggot-y things, they were ravenous.
The second clue I got was when the houseflies disappeared. I knew that BSF grubs secrete a natural fly repellant, so this was a good sign. And as my bins are right next to the sliding door to my home, the absence of houseflies is a very, very good thing.
I'm not sure how much time passed, but one day while poking around in the bin, trying to see what I could see, I finally got an eyeful of a proper BSF grub in all its glory, with its recognizably black and hardened body. The second I realized that I had what I'd hoped for, I began drilling holes in the bucket so the grubs could make their escape as soon as their instincts kicked in.
That's the only downside to Black Soldier Fly grubs, once they've had their fill of food, they are overcome with the need to leave the feeding trough and hie for greener pastures where they will hole up and morph into adult flies, whereupon for 5 to 8 days their only mission in life is to make babies. They won't even eat anymore once they're adults.
Under perfect conditions, my compost bin would be in a backyard, where the grubs could escape without us much noticing. As I have them on a balcony, though . . . things are a bit more complicated.
Shane smokes and therefore spends far more time out there than I do. To his credit, he held himself together very well when he came in one morning and announced, "You've got bugs crawling all over". I sprang up and raced to the balcony to find that "bugs crawling all over" translated to just 5 black grubs searching for a cubby hole.
Now my philosophy is that I bred them on purpose and have gained a great deal from them, so I feel obliged to help them toward their adult phase. I owe them. So, I urged them all into a plastic baggie, took them downstairs, and set them free in the grass, where the birds won't see them as easily, and where they'll hopefully fulfill their destiny, pupate, and fly up and lay eggs in my compost bin again.
Since that first fly, I've had several more lay eggs in my one bin (why not the other, I'm not sure). And I now have a pretty sturdy population, enough to see my pile undulating as they move, and to hear them wriggling about. As a reference, they sound exactly like a bowl of Rice Krispies in milk.
They've become rather precious to me, and I won't deny that I baby them, making sure they have plenty of coffee grounds, which they love, and even bringing them in the house when it gets hot enough outside to kill them (over 100 degrees). What can I say? I value them. They've allowed me to recycle so much of my kitchen waste rather than sending it to a landfill. That means a lot to me. (I don't put anything in my compost that normally doesn't belong there, e.g. dairy, meat, pet feces, etc., but apparently you can without any ill consequences.)
______________________________
If you think it might be worth it to you, too, then you should give it a try. Start composting and let the Black Soldier Flies come as they may. This could be the future of recycling, and not just for individuals. Restaurants should consider using Black Soldier Flies as well to reduce waste.
These days, you can even buy compost bins specifically made for Black Soldier Flies. Or, if you have trouble attracting the adult flies, you can just buy some grubs to get started. (I have not used and can't personally recommend either of these sites. I'm simply linking to them as an example of the resources available.)
______________________________
If you're interested, do some research to see if grubs would be a good fit for your lifestyle. Here are a few links and quotes to get you started.
“ESR International has designed both home- and restaurant-size compost bins that provide little ramps for the departing larvae to ascend. Those ramps end in a drop-off that plops the migrating maggots into a collection cup, making it easier to use them as livestock or pet feed.” Maria Gaura via the San Francisco Chronicle
"’We sent larvae to a researcher in Iowa, and they actually made them into biodiesel,’ said Craig Sheppard, a retired professor of entomology and an expert on BSF. ‘If they divert their food waste, any fair-size city could set up a bioconversion plant’ turning food scraps into renewable fuel.” Maria Gaura via the San Francisco Chronicle
ESR International: Making Waste Our Greatest Resource
Yucky but useful: Maggots make compost
black soldier fly, composting, grub, sustainability | in Food News, Gardening, Observations on Life Posted on Thursday, June 28, 2012 at 11:31AM
Reader Comments (10)
This is great info! I have to confess I haven't given much time or thought to our composting. I just toss is out there. It would seem I'd have scads of refuse, but with chickens, ducks, rabbits, and goats that all eat veggie scraps and yard waste, I actually don't have all that much, thus, it languishes in it's huge bins, not really generating enough heat to decompose. Maybe it needs some black soldier fly help!
Yes, I imagine that will all those animals you must be able to recycle a lot of stuff! For now I have to settle for my grubs and dream . . .
I had black soldier flies invade my compost last year. I couldn't take their strange smell. I am actually composting indoors now with red wigglers I bought at Buck Moore Feed. I am tots in amor with our worms and there is no smell. No one has escaped yet and the dog has stayed out. I highly recommend vermicomposting.
How weird. I've never noticed any smell at all, or read about that phenomenon in my research. But red wigglers sound just adorable. I can't wait to learn about them. Thanks for the tip!
I had a compost bin for a few years - watermelon rinds, cantelope rinds, veggies, etc. Then I got a LOT of maggots, maybe something else. I stopped putting stuff in. One day I needed some soil in a flower bed and went to the compost ... the BEST soil in the entire world ... my oh my, how plants grew!! Compost bins are a delightful surprise but it takes a bit of dedication and effort to keep them going. Good luck on your efforts!
Thanks, Aunt Doris. You're right, it really does take some effort. Of course, it would be a lot easier if I had a proper BSF bin and an actual yard to work with, but I'll keep doing this until it becomes untenable. If nothing else, I've learned SO MUCH and had a lot of fun in the process.
This is fabulous information! I hope that I can attract them. And I love the fact that they repel house flies!
Oh, gosh. I'm so glad that I found your post so I could read the benefits of the BSF grubs. My compost pile is LOADED with them. And your right, I never see any flies and the compost has no foul odor. I have so many though that it freaked me out a little. I sometimes will take scoop out a bunch and toss them to the chickens. As much compost-able material that I add, the pile doesn't grow much. I guess the because of the efficiency of the grubs. I've also used red wiggler inside for kitchen composting, we did it for a few years. Overall a good experience but at some point we had a problem with gnats so we got rid of it.
Linda, Thanks for the comment. And, yes, it is such a relief to not have houseflies on the balcony!
Roberta, I'm so glad you found it, too! If I hadn't read about their benefits before finding them in my bin, I definitely would have freaked out. You're a braver soul than I am.
Oh, I wish I had chickens to feed them to! Well, a girl can dream.
Thanks for the info. on red wigglers. I have noticed a few gnats in my bins with the grubs, but it isn't really a problem, as they don't seem to want to come in the house, and there aren't too many of them.