Tuesday, March 1, 2011

Using worms and black soldier flies in the garden

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Last Spring I started hearing about black soldier flies (BSF) as a great resource for composting food waste (even better than worms) as well as a high-protein food source for poultry. I found the best site to learn about these insects at where I was able to find plans and videos for building my own bin out of a five-gallon paint bucket. Jerry is the site owner and designer of a commercially available BSF larvae bin (biopod), and is very happy to respond to questions that you may have about his designs or black soldier flies, in general. I was also able to order a batch of larvae from him, since these flies are not native to Utah. People who live in the Southern United States can bait their bin and expect to attract wild BSF flies to lay eggs and start colonizing their bin at no cost.

What I found after trying to raise my own BSF was that they consumed food waste quickly and in large amounts, just as it has been promised. I was hoping that after enough BSF reproduced, I could start a second BSF bin and start feeding them to my chickens. There are quite a few people commenting on the blog how much their chickens love to eat the larvae. Obviously they are very high in protein and a good supplement to their regular feed. Here is a video from YouTube showing what a small colony of BSF larvae can do to a fresh hamburger in five hours (I didn't have this many larvae, nor the wish to have them eat a perfectly fresh hamburger that I had just bought):

Unfortunately I didn't understand the reasons why BSF don't naturally thrive in the arid environment where I live. Although there are plenty of neighbors with horse and cow manure which the flies like as a food source and a good supply of food scraps that I left in the bin, I found that the larvae would mature, leave the bin, transform into adults with wings, and fly away. There were a few adults that flew back to lay eggs, but there weren't enough eggs to keep the whole colony going. (They look like wasps as adults, but they are harmless and only live long enough to breed and lay eggs.) I also read on the BSF blog from others living in cold climates how the larvae are difficult to keep alive during the winter. Despite their potential advantages, I abandoned my BSF plans last year.

This winter, I decided to see if I would have better success with earthworms that with the BSF larvae. I used the BSF bin that I created from two five-gallon buckets, and removed the extra pieces that the worms didn't need. (The inside bucket was drilled with a bunch of small holes so that excess water and "compost tea" would drain into the second bucket.) I used a paper shredder to fill the bucket half full of shredded newspaper which I then soaked in water. I bought a couple of containers of worms from Walmart (where they sell fishing equipment), just to try it out. The fifty worms have survived just fine in my garage, but they were not active enough to eat much of the food that I left for them. The larger scraps were not touched, but the smaller scraps were starting to be broken down. I tried moving the bucket to the laundry room where it was warmer, but my wife didn't appreciate it there. It is for a good cause, right? :-) For now, it is tucked away in the basement until I can find a better place. Being in a warmer place has encouraged the worms to be much more active.

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I'm hoping to get a larger bunch of worms that will be able to break down food scraps faster (before they spoil and get moldy) and to be able to use the worm castings in the garden. If some of the worms end up in the castings, it is just going to help the garden or provide a nice treat for the chickens. I'm thinking that the Canadian earthworms that I already have were good for this "test" but I would rather put my money towards the more productive worms used in traditional vermicomposting.  Red wigglers are much smaller and you can buy a pound of worms (about 1000) for around $25. This rate is obviously much cheaper than the ones that I bought as bait worms, but most places don't sell them in amounts smaller than a pound. There are many, many, places where you can order them online, but without knowing for sure, it is probably preferrable to find a place that will sell you a few different varieties in your order since some may be better suited to your location than others. (I'll let you know when I end up ordering my own red wigglers)


  1. Anna over at Walden Effect blog just happened to write a post about black soldier flies today too. Interesting coincidence!

  2. I'm glad to hear some first-hand data. We're still in the planning stages, so don't know if they'll work for us yet. It does sound like if you're outside BSFs normal range, they're probably not worth the expense, but we're hopeful that we'll be able to attract wild flies.

    You might be interested in reading about our worm bin project --- Surface area is key with worms, so you might want to change to a wider rather than deep bin. Good luck!

    (Cross-posted over on your blog just in case you don't check back here!)

  3. Thanks for your response, Anna. You have done a wonderful job at documenting your garden experiments with worms, both successes and failures. This confirms that I really need to find a way to expand my use of vericomposting in the garden. Our alkaline clay soil has low bacteria presence and low micronutrient levels, both of which can be addressed with integrating worms into the soil preparation.

  4. David,

    I tried to raise the Black Soldier Fly in Utah too. I live in Lehi. My purpose was to have a constant source of food for my reptile and I came across Jerry's site. I built a BSF bucket and ordered some grubs. However, I did it late in the summer, which I felt was too late. Jerry told me that due to the high altitude in Utah that the grubs would not be able to reproduce. So, I contacted an entomologist at Utah State University who told me that the BSF should do well in Utah. He also told me that the BSF can be found in Utah as well.

    I was able to raise quite a few BSF to full maturity. I thought that if I put them in my reptile cage that has high humidity and a constant heat source they would fair better. So, I put them in a container with some pieces of cardboard, hoping they would mate and lay eggs. I got the same results as you did. They just died off.

    What I can't figure out is that there have been studies done in both Idaho and Colorado, which have similar climates as Utah and the BSF has been used effectively to reduce animal waste on farms, especially cattle. So, my question is why not Utah?

    Just my two cents worth.


  5. I wish that I knew what the problem is. I have come across others in Utah who have tried the same thing with various levels of success, but even the most successful can't seem to last through the winter. If I had a greenhouse where it was humid and warm all year round, I would try again, but for now I'm going to stick with composting worms. (I'll type up my recent experience with this soon.)

  6. David
    Earthworms are not effective for composting and they do not reproduce as well either. I bought my eisenia fetida of an add on Last summer my worms ate loads of food and they reproduced well.

    I also live in Utah. This was the first winter that I have had a vermicompost bin in the garage 40 - 50 degrees (never freezing, but never optimal temperatures). In the summer I rotated my bins every week. Through the winter months I have watered, emptied the water bin, and feed the worms, and at that only minimally. This Saturday March 24th 2012 I will add another bin for the worms to crawl up into, and check the lower bins while I am working on the project.

    My goal is to have accumulated a large amount of worms (live) to start a 2X2x6 foot outdoor trench in the garden the end of May.

    Any guesses as to if I will have any worms survive the winter cold garage?

  7. Since my original post, I have also started a red wiggler (eisenia fetida) compost bin with 1 pound of worms starting around June 2011. The worms have been doing fine in a plastic bin in the garage over the winter. I made sure that there was plenty of bedding in the plastic bin for the winter, but I didn't worry about extra insulation or heat source. They haven't consumed much food waste during this time, but there has still been some activity.

    Last fall I tried adding a new bin for the worms to crawl up into, but I found that about a fourth of the worms stayed in the bottom bin even though the food waste was in the top bin. I'm guessing that there must have been lingering food sources in the bottom bin... perhaps even liquid from the food waste that dripped down to the bottom bin.