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Starting my third year with the black soldier fly

I’m going into this season with a small colony made up of grubs that were laid last fall. Where I live the winters are mild so it was fairly easy to maintain the colony through the cool months. At the end of last summer my BioPod was full of compost and I should have harvested it. As a result of that neglect my beautiful compost became anaerobic, dense and a bit smelly. What can I say? It’s been a hectic year. I think early fall may be a good time for removing the BSF compost because the grubs are likely to be less active on average in winter versus the warm months. I believe the churning action of a very active colony (summer) is an important factor in keeping the compost aerated and “fresh”. I said early fall for compost harvesting because I’m afraid that if you wait too long in the season you won’t have time to rebuild the colony to near maximum size in preparation for the winter when BSF breeding stops (unless you’re in the tropics).

Spring cleaning

BSF don’t normally land on people,

but this one had just emerged from it’s pupa so I was able to handle it.

I removed all of the compost and washed my BioPod. I hand picked a few hundred of the light colored juvenile grubs from the old compost and added them to the unit along with some fresh food scraps. I didn’t clean the grubs themselves so a small amount of the old compost was transferred along with them. This old material will act as a great attractant to BSF adults who have now started the mating season. A healthy and balanced BSF colony doesn’t have a strong or bad odor, but the females will always be attracted to the faint scent of an established colony. As I mentioned previously, my compost is anaerobic now and therefore smelly, but the typical mild smelling compost from a balanced culture would work just as well.

A new drain

As you can see from the first photo in this post I have replaced the BioPod’s liquid collection jar with a straight drain into the ground. (I hope you won’t be too disappointed with me Dr. Olivier.) I haven’t been gardening and to date I haven’t done anything productive with the liquid (also called “tea”). For that reason I’m opting for the convenience of the straight drain for now. To see how I set up the drain you can go to my “Tips and Tweaks” page.

The pond

You can also see my pond in the photo. I moved the BioPod near the pond because I’ll be feeding fish scraps and culls to my BSF colony this year. I don’t enjoy killing fish, but to maintain the population in a healthy balance I will be removing some of them. I’ll have some help from birds, turtles, and snakes, but the pond is fairly close to the house and wild predators are limited. With the BioPod I’ll be able to convert the excess fish into nutritious black soldier fly grubs and return them to the pond as fish feed. I have a post about my philosophy regarding feeding BSF grubs to other animals here.

Black soldier fly grubs are also fantastic fish bait, so having the BioPod near the pond will be very convenient for fishing. I’ve created a page about BSF as bait which you can find here.

Winter BSF culturing

As I mentioned earlier I did keep the colony going through the winter, but I didn’t keep any records. The one thing I can confirm is that the BSF grubs will interrupt their usual development during the cold season. I had very few BSF laying eggs by October and the last one I observed laid her eggs late in that month. By November I stopped seeing any smaller grubs in my colony. I assume then, that the grubs that currently make up my colony are at least five months old. During the summer this stage would only last 2-3 weeks. Next winter I want to be better prepared to test cold weather bio-composting and I hope that some of you will participate in it with me. At the end of this summer we should start a thread about this at the BioPod forum to share strategies and results.

Logging this year’s results

My goal this year is to keep a log of all the food I add to the colony and the weight of the grubs produced. I’ll be fairly general about recording the composition of the food scraps so this won’t be a controlled experiment. The fact that I’ll be adding a large amount of whole fish and fish scraps will certainly effect my results. My goal is to provide a general outline of what you might expect. You can find the log in the column on the right of this page under Black Soldier Fly Pages, or simply click here.

Update: Since we now have a discussion forum we will be disabling comments here on the blog. Anyone can read the forum, but to join in on the conversation you will need to register. This is an easy and painless process, and it’s necessary to keep spammers from, well, spamming up the place.

The forum can be accessed here (forum) and you will see a link for registration in the upper left corner of the forum. The legal language on the registration form is very basic and is what came with the forum software. In short, we won’t share your information, and please don’t be vulgar or break the law.

solider

I’ve been feeding BSF larvae to my redear sunfish (shellcrackers) everyday for about a week and they are taking them with enthusiasm. They have a preference for the immature larvae over the dark prepupal larvae, but they still eat the dark ones pretty well. I think the prepupal larvae might be more foreign to them than the light colored larvae, but I think with some conditioning they will eventually accept them just as well. There are some individual fish that already take the prepupae well which is why I suspect it isn’t a taste issue or something like that.

(Wow. That video quality is terrible. I’m open to suggestions if anyone would like to offer some advice about uploading video. I’ll leave this up for now, but I have to do something! I tried blip.tv and PhotoBucket which were better quality, but the embedded players for these sites ruined the xhtml validation for my blog, the YouTube videos don’t.)

Here’s a link to a better quality version of the same video at Blip.tv – VIDEO

Update – August 14

These fish are in a pond that was built in January 2008 and I only stocked 24 adult redears. (I also stocked 110 very small redears in late March and you can see a few of them feeding with the larger fish in the video) At first when I began feeding them BSF larvae the fish were concentrated in one area of the pond because they were on spawning beds. This made it very convenient to hand feed them, but I assumed they would disperse once the spawning season passed. Well, the spawning seems to be over and they’re still concentrated in the same spot, and I’m pretty sure it has something to do with the daily offerings of black soldier fly larvae. Lately when I walk up to the feeding area I see the fish lining up just off the bank of the pond about one meter from the water’s edge. All fish are oriented on me as they wait for the rain of tender BSF morsels. They will swim into water that is only a few inches deep to snatch up the larvae. Previously I was unaware of the popularity of fly larvae as fish bait, but now I can understand why they are so effective.

If you’re a sensative person you may hesitate at the idea of sacrificing the larvae to fish this way but there is another way to look at it. In nature fly larvae have a high mortality rate and the balance of the population is based on the vast majority of them not surviving to reproduce. Two BSF can produce between 500 and 900 eggs depending on which report you read, and to maintain the normal population only 2 of those several hundred will survive to lay more eggs. I address this issue in more detail here: Feeding black soldier fly larvae to other animals

Black Soldier Fly Blog

refreshing the colony