Random thoughts related to culturing black soldier fly larvae:
Hermetia illucens-the black soldier fly
Dry Pasta 9/27/9 – I added 1.5 lbs (.685kg) of uncooked pasta to my BioPod last night. Because it was dry and hard I expected that it would take several days for it to be consumed as it gradually absorbed the ambient moisture. When I checked the BioPod this morning all traces of the pasta were gone just 12 hours later.
Sawdust 9/27/9 – I often add a few handfuls of sawdust from non-pressure treated wood to my BioPod. Pressure treated wood contains insecticide, not a good thing for BSF. My feeling is that the sawdust might work as a moisture buffering agent. By that I mean it will soak up excess liquid when it’s present and retain it to help keep the compost consistently moist. Moist but not wet is the perfect balance. The texture of the compost in my BioPod is almost always like potting soil; damp but not sticky and with a loose “fluffy” texture. It’s true that the sawdust adds bulk that will fill up the unit faster, but I don’t see that as a big deal, especially if it results in a more consistently aerobic (aerated) environment.
Shady spot/sunny spot 9/29/9 – Myself and others have stated that a BioPod (or DIY unit) must be kept in full shade, but there are exceptions. The real point is about regulating the temperature of the colony which must not exceed approximately 110ºF internal temperature (BSF reportedly die at 116º). If you live in a hot climate but you’re trying to establish a colony in the spring it might be best to keep your unit in at least partial sunshine. People in cooler climates might find that they can keep a unit in a partly sunny spot all summer. I’ve heard from several sources that black soldier flies are common in Vancouver, B.C., and I expect you could keep a BSF unit in a sunny place there for most of the mating season.
Loose insulation 9/30/9 – The recommended way to insulate a BSF colony for winter operation is some type of rigid material like Styrofoam cut a little smaller than the inside diameter of the BioPod or other unit. The gap at the edges allows the larvae to come up for air and to cool off. To add food scraps you must remove the disc, add the food and then replace the disc.
One time I processed a large quantity of fresh corn kernels. The larvae ate the soft middle part leaving the paper thin skin of each kernel intact. This created a layer of material that floated on top of the waste. It was summer at that time I remember being concerned that the layer would trap in unwanted heat causing juvenile larvae crawl-off into the collection bucket. It occurs to me that in winter you could possibly use some type of insulation that would float on the waste allowing a one step operation when adding new food scraps. I wonder how packing “peanuts” would be? Maybe this wouldn’t provide as much insulation as a solid disc, but in areas with mild winters it might be a viable alternative.
Vacation “feeder” material 10/1/9 – Regular additions of food scraps help keep a black soldier fly colony balanced. Time released food items might be helpful when you can’t add scraps to the unit for several days at a time. BSF seem partial to corn and dry whole corn kernels or cracked corn like that fed to birds might serve as a long term food source for the larvae. As the grain absorbs ambient moisture it will gradually soften so the larvae can eat it. In a relatively dry climate it may be necessary to soak the corn for a period of time. Raw potatoes might also serve this purpose. They contain more moisture so might be preferable in dry areas. I normally don’t condone feeding good fresh food to the larvae, but I make exceptions for the sake of maintaining the colony so it can be used effectively in the future.
The relative rareness of BSF adults 10/1 – I’ve often stated that BSF adults are rarely seen even around BioPods and DIY units full of larvae. Some people have contacted me to say that they aren’t rare on their property because they’ll often see several at a time around their units. I still say that BSF are relatively rare because you might see 4 or 5 at a time, but how many house or blow flies would you attract if you tried? I think the most* BSF adults I’ve seen at once around my unit was 15 and that’s with me doing everything I can think of to attract them!
*I’ve actually seen a few hundred at once, but that consisted of newly emerging adults from my “incubation” bucket that I protect pupae in. I had a few thousand pupae in the bucket and a large number of them emerged at the same time. I don’t count this because they didn’t go to the BioPod, they went into the woods to seek a mate. After mating the males aren’t attracted to any type of food so you probably won’t ever see one of them. The females may or may not return to the BioPod, but if they do it’s still only a handful at a time.
Overfeeding is a common mistake 3/22/10 – People usually run into problems when they first start using black soldier fly larvae to compost food waste. The most common issue relates to anaerobic bacteria which cause foul odors and create a less than optimal environment for the larvae. A very simple way to help moderate these problems is to resist the temptation to overfeed your colony. This is especially true with new colonies made up of only a few thousand individuals. To process waste in substantial quantities you need the equivalent of a 2 – 3 inch layer of BSF larvae. A simple rule of thumb is that, on average, food scraps should be completely consumed within a day or two. Hard items like root vegetables will take longer, and soft items like fruit, dairy products and rotting vegetables may be eaten within hours or even minutes. In cool weather these time frames will increase as the activity of both larvae and bacteria slow down.
The type of food is also a factor. To illustrate this let’s compare processing raw potatoes and watermelon. If you add 10 pounds of raw potato to your unit it may take several days or even a few weeks for the BSF to process them completely (see Vacation “feeder” above). This is because the larvae don’t actually chew food, they scrape away softened pieces instead. This is why they generally target rotting food or manure and are not a pest in gardens. This is also why animal flesh is not their preferred food.* In contrast, if you add 10 pounds of watermelon the BSF will consume it quite rapidly. This will release a large quantity of liquids, and if your unit does not drain well then you are at risk of flooding the compost and encouraging the development of anaerobic bacteria and therefore foul odors.
The skills required to operate a BSF composter are not complicated and the best way to learn is through observation. Watching the larvae work and taking note of the condition of the compost on a regular basis is the best way to get a good feel for how to keep the system balanced.
*It’s fine to add meat products to a BSF unit, but it should be completely consumed within a day. If it isn’t finished quickly then I recommend removing it and discarding it another way.
Starting a new BSF colony using earthworms 3/23/10 – For most people one of the biggest challenges with BSF composting is establishing the colony of larvae. Even in areas with existing BSF populations it can take weeks to attract egg laden females to your unit. A starter kit of BSF larvae is very effective in attracting the locals, but there are other solutions for speeding up the process. BSF larvae are often discovered accidentally in traditional compost piles and also in worm bins. In the past I’ve recommended starting a compost pile to attract BSF and starting an outdoor worm bin would work similarly. However, a person may not want to go through the steps of setting up a dedicated worm bin, so what about simply adding a small quantity of worms to your new BSF unit along with the initial food scraps?
Often while you wait for BSF to discover your new BSF composter you must deal with other entities that find it first, like fungus, mold, bacteria, and a variety insects. The first food scraps you add to the composter can get pretty nasty after a few weeks of waiting for the BSF females. Maybe a small number of worms, and possibly a little soil, would serve to stabilize the waste until the BSF show up. Worms are readily available and I imagine you could find a suitable variety in a nearby bait store for a few dollars. Worms and BSF are known to inhabit the same waste without harm to either species, but if I understand correctly the worms used in this way would probably perish eventually as the temperature rises in summer. Ultimately the worms would serve as food for the BSF. In the case of cooler regions like the Pacific Northwest, the worms might continue to thrive along with the BSF. Combining worms and BSF is an intriguing idea and maybe you folks in the NW have the right conditions to accomplish this.
I haven’t worked with worms so I can only speculate, but if the weather was still fairly cool I believe the worms would survive long enough to
Stumble upon it!