Introduction: Fly Cage Black Soldier Fly Breeding UK.

Hello my fellow builders.

This is a big project BUT it can turn all of your household food waste or even dead fish from your Aquaponic or aquaculture system into high protein feed for your animals. Black Soldier Fly larvae are the best, balanced feed for chickens, lizards, fish and anything else that benefits from high protein feed.

The box is a self contained environment that will allow you to breed BSFlies all year round. It is insulated, heated and provides everything you need to raise maggots all year round.

The list of what you will need for this build will vary. You lucky sods who live in hot and sunny places will only need to build the frame and cover it with mosquito net.

For those of you who live in the UK, you need to insulate the box, provide heating, lighting, a lecking place (Usually leaves, where the female sits and waits for her mate) and airflow.

So here is the list.

-Sheets of thin ply wood. 6-8mm
-Sheets of thicker plywood. 12-16mm
-Sheets of Celutex insulation board25mm thick.
-Lengths of 50mm batton.
-Wood glue.
- Decking screws.
-4" Extractor fan.
-4" Ducting
-4" Carbon air filter
-Mosquito nets
-Door draft excluder sticky strips
-Oil heater
-50Watt LED floodlight. (MUST BE 50w or more or flies won't mate. They require BRIGHT sunlight.)
-Circulation Fan.
-Bottles of liquid. (They store heat and help prevent wide fluctuations in temperatures.
-Thermostat controlled Plug. (One for hear and one for cool. )
-Inline on/off timer.
-5m of 3 core cable and a plug.
-Maggot bin. (This box has space for 2 bins like the wooden one I posted a while ago. Without this you have nowhere for the maggots to eat. You have nowhere to feed them.)

-Cut off /Mitre saw

Step 1: First the Insulated Base.

Size matters. Now what some of you will like to hear but it is true.

Black Soldier Flies require a decent area to fly around because the first part of their mating ritual is aerial.

I chose to build a box 1.2×1.2×2m tall..

For step one we will be using 50mm baton.

Cut 4x2m Lengths and 9x1.2m lengths. (The extra length is for the door which hangs off the cross piece.

Next cut corner supports for each corner. Out of 50mm Baton about 20cm long with two 45°angles.


For your corners you could also use
Building restraint straps, cut into 20cm lengths and hammered to 90°.

Now put together the frame.

Step 2: The Floor.

Now that you have a frame, you need to make an insulated floor.

So, cut a piece of +-16mm ply to the exact outside dimensions of the floor.

Now tip your frame over, apply wood glue to the bottom of the batons that were previously touching the floor.

Now screw the plywood bottom onto your box.

Now that you have the bottom attached, lift the frame back up. Your 16mm plywood bottom should now be all that touches the floor.

Next, cut 25mm celutex to fill in the floor, inside the square made by the bottom batons. Once in place the celutex should completely hide the 16mm ply. Like in picture 3.

Lastly, cut thin ply wood to cover the celutex over. It too should fit inside the square made by the bottom batons.

Once in place, varnish the thin layer of ply and then silicone around the edges to prevent any future spilled water from seeping into the celutex which insulates the floor.

Once done, your floor should look like picture 5.

Step 3: Putting on the Sides of Your Box.

The sides of the box are simple.
A layer of 25mm celutex covered on the outside with a thin layer of ply wood 6-8mm ply is perfect and cheap but provides protection for the celutex.

Start with the back of the box.

What I did was run a bead of silicone around the baton frame then stick the celutex to the frame.

Next I would place the thin ply over the celutex before screwing through both the ply and the celutex into the baton.

Once the back of the box is on, you should cut the celutex and ply wood for the Left and Right sides but don't stick them in place just yet.

You are going to put a mosquito net across the front of the box, above the cross piece. The sides will hold this in place. You can see this in picture 4 above. I will explain how I did it in the next step.

Step 4: Your Mosquito Net for the Summer Time.

Run a bead of silicone along the left and right rear upright.

Now put the left and right side sheets of celutex and thin ply wood in place but only screw them in along the rear upright on both sides.

This will leave space for you to put the mosquito net in place.

Once you have cut your mosquito net to leave you with a double layer, run a bead of silicone around the front upright and both cross pieces on each side.

Now put the mosquito net in place on one side. Get it laid smoothly over the silicone then push the celutex+thin ply onto the silicone on that side before screwing it in place. It should now look like picture 1and 2.

(Be careful not to let the screw grab hold of the net as it will pull it all into a bunch.)

Now stretch the mosquito net over to the other side. It needs to be smooth and quite tight but don't stress the little bumps, they will go when you stretch the top and bottom later in the build.

After securing the other side it should look like picture 3 with the mosquito net covering the entire front.

Now you need to cut the left and right sides of the mosquito net covering the space under the middle cross piece.

Now fold the mosquito net around the back of the cross piece and stick it in place, try to stretch out all of the bumps in the process.

Step 5: The Roof and the LED Floodlight.

This is a few steps in one.

1. Cut a piece of thin ply to cover the entire roof but only screw down the back. Now cut celutex to fill the cavity below the roof inside the surrounding batons.

2. Now, cut a length of thick ply to hold the celutex in place. Screw this length to the underside of the batons between the front and rear top cross pieces.

3. Mount the LED flood light to a 30cm length of 50mm Barton then screw the bottom to the cross piece of plywood from #2 above.

4. Cut a hole in the side of the box at the top. The side you choose should be easily visible to you where you plan on running the box.

5. Mount the in line 24hour timer to run the floodlight while also mounting the thermostat controlled power plugs. This will control your heater to keep the box inside the optimum breeding temp range. Carve out a section of celutex to flush mount both the thermostat controlled plugs and a 4 plug extension lead which will be powered 24/7 from the power entering the inline timer.

6. Stretch out the mosquito net and screw down the rest of the roof to hold it in place. Now your mosquito net is stretched out smooth and your light and power is done.

Step 6: Covering the Mosquito Net in Winter.

Cut a piece of celutex and thin ply to cover the mosquito net in winter. Screw it in place above the cross piece.

I cut a circular port and put on a door with a seal. This allows me to check on the system without opening the big door, just the little one towards the top of the cover of the mosquito net.

Now for the door.

Cut a piece of celutex to cover the opening. Now cut two pieces of thin ply wood to cover the inside and the outside of the door. (I used offcuts for the inside of the door)

Now bolt the door together and bolt the hinges to the door before sxrewing them to the cross piece.

When the door opens it should sit up like in picture 5. I use a bunje cord to hold it up.

Step 7: Finishing Touches.

OK the last bits.

1. Cut a 4" hole in the back corner opposite to the power timer for the light. This will run as needed to clear any smell. (It should only smell if you put too much meat into the system)

2. Mount the carbon filter to the inside below the extractor. This eradicated the majority of smells while preventing flies from escaping.

3. Hang your small oil heater from the roof to hang just above the cross piece. This will plug into the heat plug of your thermostat controlled plugs. Set the heater to 80% if it has it's own thermostat. Alternatively if you prefer not to use the thermostat controlled plug, you can experiment with the heater and discover how high to set it to keep the temp between 26 and 30°C.

The only other heating option is to use a big bucket of water with a fish tank heater inside. This provides less heat but will have less fluctuation.

4. Hang as many cola bottles down the back corners. The liquid will hold heat and stop huge fluctuations.

5. Fit a fake branch of leaves about 30cm from the top to the box. The females will sit on the leaves and wait for the males they choose.

6. I set the extractor fan to run for half an hour 4 times a day. I also made it vent into a pipe that carried it's exhaust out through the wall.

Step 8: Now You Need a Maggot Bin.

Now that you have a happy breeding environment for your flies, you need a bin to raise the maggots in.

I recommend the wooden design I previously posted. 2 will fit in your fly box. This also has the benefit of auto harvesting into a bucket of flour. Just pass it through a seive and you are sorted.

You can put in anything that you can eat. Unlike worms, there is not much out there that maggots won't eat except egg shells, sticks and bones

I recommend adding some bokashi bran to the system to help break down the food you add and try not to add too much in the way of meat at one time.

I made a big mistake when I left my return pipe to one of my fish tanks turned off all weekend. I lost sixty trout and threw them all into my fly box. I took pic 5 and 6 just 18hrs apart. The problem is, they quickly began to stink because there was too much meat for a single bin to process fast.

My fly box provides an average of 2kg of maggots each week which feeds my 200 trout easily. This has made me self sufficient, free protein and less waste. The castings makes a great compost.

The last advice I can offer is this. While processed food does not smell bad, if you put too much food stuff in before the maggot population is high enough, the unprocessed food could start to smell. This is where the box comes in.

If constructed properly and vented regularly (by the extractor fan), your box will not smell. To be safe I recommend using draft excluded tape to seal any gaps that could let the smell out. This will mean that the only air leaving the box goes through the carbon filter.

The only other thing is humidity. 80% humidity is ideal for egg hatching. If you live in a dry region then you can set up a cheap humidifier to run a few times a day.

Anyway, I hope the build goes well for anybody who builds the fly breeding box. I am happy to answer any questions you have.

Happy building!

Step 9: Edits to the Build.

OK so after a question from FearAndLoathing, I spent half an hour and made a quick alteration.

So, the problem I was having was every time I opened the big door about 20 flies escaped. I tried installing a net curtain over the entrance but it just got in the way. So I decided to make a new, smaller door that would fit one of my 5L black buckets and would allow me to add food without loosing breeders.

If you look at the pictures.

1. I took a handheld circular saw and pulled the blade guard completely back before using it to cut the straight lines.

2. I used a reciprocal saw and cut the corners where the round blade didn't cut the whole way through.

3. I pulled out the square and used a 2 part epoxy to attach hinges...

4. After 10min, when the 5min epoxy was strong I did the same again, sticking the hinges to the front of the box, making the square fit into the hole it came from.

5. I used a rasp file to shave the bottom edge off the insulation to allow it to work.

6. I fashioned a handle that acts as a lock too.

10. I added food through the small hole quickly and easily..

Hope that helps.

Tip. To avoid smells, try not to add a huge quantity of fish all at once, the ammonia from the process of breaking down all that fish as well as the fish itself can get pretty nasty.

My last thing that I would do differently when building this box is that I would use a 6-8" extractor fan + carbon filter set rather than the 4" one I used

I hope this helps everyone.

This is an answer for Kingers.

Hi there.

Thanks for the questions.

Ok so for the carbon filter I would stick with a 6".

It will not run for long. I have actually found that air turnover is pretty low in general.

I use a temp controlled Heat and Cool plug system.

When the temp is under 15°c the heater turns on.
When it's over 27°C the extractor turns on for a few min.

The rest of the time the air just sits. I run a small 6" clip fan to move the air around inside the box. it keeps the air mixed and stops the hot air from pooling at the top.

Overall the box has been a massive success.

The only thing I will say is that you need an ozone generator to kill the smell.

I use a small system with a 4mm air hose. This runs for 15min per hour with the 4mm air hose dropping ozone into the top of the box. Without it, smell can become an issue but with it there is no smell.

I hope that helps.

Let me know if you have any more questions.