How I Learned to Stop Worrying and Love the Grub


Why start the day with the Wall Street Journal when the real excitement is to be found in periodicals such as Backyard Poultry Magazine? While our broke nation can’t afford missile shields or moon trips anymore, at least it’s comforting to read in the pages of BPM that the citizens of Bonner Springs, Kansas can visit the brand new National Poultry Museum. This month’s issue of BPM also has a fascinating article by Harvey Ussery, “Black Soldier Fly, White Magic” on raising black soldier fly (Hermetia illucens) grubs as poultry and fish feed.

“If we offer the grubs 100 pounds of food wastes, for example, they will reduce it to 5 pounds of residue usable as a superior soil amendment, in the process generating 10 and possibly up to 20 pounds of live grubs that can be fed to livestock; in addition to liquid effluent (how much depends on the moisture content of the feeding materials) which can be used to feed crops. Hey, wait a minute–what happened to the “wastes”? There is absolutely no waste remaining after this conversion–it has all been transformed into valuable resource.”

To raise Hermetia illucens you put vegetable and fruit trimmings in a container with a small opening for the black soldier fly females to fly in and lay their eggs and a method for the grubs to climb out of the compost. You can also feed them small amounts of fish and meat but they can’t digest cellulesic materials. A company called ESR International markets a black soldier fly growing system called the BioPod™ at www.thebiopod.com. A spiral ramp in the BioPod™ allows the grubs to scamper out of the feeding materials and launch themselves into a bucket. Each morning you empty a bucket full of grubs for your grateful chickens or fish, making sure to reserve a few to ensure future black soldier fly generations. Adult black soldier flies don’t bite and are only interested in flying around looking for sex and, in the case of the females, to find a good place to lay eggs.

At $179, the BioPod™ is above our humble slacker budget level, but you can make your own out of the ubiquitous five gallon bucket. While I haven’t tested this design, there’s some simple plans on this informative blog devoted to the black soldier fly. The author of this blog, “Jerry aka GW,” cautions that growing grubs requires attention to detail and will be easier in warmer climates such as the southeast and west coasts of the US where soldier flies can be found in the wild. While you can buy black soldier flies to populate your composter, it will be easier to grow them where they already live. Here’s another DIY grub composter. If any of you have experience with building one of these please leave a comment.

And while you’re ditching the Wall Street Journal, why not skip the Netflix this evening! Here’s a video on grub growin’ complete with a dramatic musical conclusion:

The crank in me has to add that simple ideas like becoming a grub cowboy are more exciting, and have greater potential than all the Priuses and algae fuel schemes combined. Growing grubs is an activity many of us have done accidentally. Making use of those grubs is just a matter of inserting ourselves into one of nature’s clever recycling schemes.

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11 Comments

  1. I love my BSFL! I give the mature ones to the gal who sells me eggs.

    My bucket is one of the big Rubbermaid containers – hubby split open a piece of PVC to act as the exit ramp for the pupating-ready larvae to crawl out on. It’s currently covered with a random piece of window screen we had lying around (provides plenty of opportunity for more eggs to be laid and baby larvae to fall in) weighted down with some old bed frame chunks hubby had lying in his metal scrap pile. I occasionally find a local varmint (we get cats, possums, and raccoons regularly) have disturbed it, but I think they’re usually so startled by the cover beign there and nonrigid that they don’t actually get to grubbing in the bucket. Yet. My BSFL showed up uninvited when I was still trying to get a worm bin going in said bucket. Instead of running screaming I hit the internet and found out what they were. I think I like them better than worms!

    My biggest issue was it going septic (ew…stinky!) due to overload/high moisture content. Mixing in some coconut coir to help absorb the excess moisture has helped immensely with that. I’m also noting lately that my self-harvesting is way down – they’re just finding plenty of dry spots in the bucket to pupate and not bothering to climb out…

  2. A few years back these buggers moved into my composter, and at first I thought they were wasps, which is bad because I’m sensitive to their stings. But I too looked on the internet and discovered that they were benign so I left them to do their composting work. The larvae were getting a little out of control, so I started to give them to the chickens I had at the time. They would go absolutely bonkers, it was like chicken crack. As soon as they realized I was giving them their favorite wriggly treat a chicken riot would ensue. Tons of fun.

    I don’t have the chickens anymore and the flies aren’t quite as prolific, but they’re still hanging out in the composter.

  3. My compost pile always has tons of those black fly larva, but I also have lots of bigger, jucier grubs (whitish, get to be as big as my little finger, smaller ones curl up like roly polies) which I sift out of my compost when it goes in the garden and feed to the chickens (definitely chicken crack!!) I have never been able to figure out what these grubs mature into, though. Moths? Beetles? Way too big to be flies. They DO look like something you would be forced to cook and eat on Survivor.

  4. Hey Sue,

    Probably green june beetles–Scarabaeidae Cotinis nitida. Like the soldier fly larvae they help break down compost and are beneficial insects, and yeah our hens like them too. Another bug for the folks at 1916 home to fry up! Mmmmmm.

  5. HE – I hadn’t seen distinctions between green June bugs and Japanese beetles before looking them up thanks to your comment. Since I’d been told by an arborist that our plum had Japanese beetle damage I assumed all of our larvae were Japanese beetle, but based on how they’ve looked in the garden, they seem to be green June beetle…

  6. I had a bunch of BSF larvae move into my compost pile a couple of months ago – I had too much wet and “green” material, apparently. At first I was concerned, but a quick search of the internet revealed that the larvae do an amazing job of converting kitchen waste into compost. So, I let them do their jobs, and wow – do they work fast! The only problem I’ve seen is that the pile can get way too wet and stinky – but I’ve just been adding lots of dry leaves and shredded newspaper, which has solved the problem. And now, I’ve got tons of nice, black compost ready for the garden!

  7. I’m impressed with how calmly others have handled their compost being invaded by BSFL. The first time it happened to me I literally shrieked, cried and ran around the yard for an hour in hysterics. I hate things writhing where there shouldn’t be anything writhing.
    I am generally a vermicomposting savant, but one day after many uneventful years of composting with worms, I got overly excited and overfed them. BSFL ensued- I was disgusted. I try to keep my compost in balance to avoid them, but since I have chickens, I guess I should let them breed so the chickens may have some crack.

  8. BSFL and worms can live quite well together. if the mixture is to hot worms run away BSFL will eat as long as there is food, if 10% of them die before hatching no biggy the worms will eat them. I have been doing this for 5 yrs I have 10 compost 4x4x4′ bins and create about 15 tons of compost a yr, amazing! The BSFL body’s tend to be flatter than grubs and the a profile of them has ridges instead of waves. Squish a grub when you find one or get chickens

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