This is a maggot feeding box that is self harvesting. I came up with the design as a natural progression from my previous maggot box which worked well but was not as efficient as I wanted. The new shape also allows me to fit two of these into a single fly breeding cage.
Step 1: Marking Your Wood.
I used marine ply wood for this grow.
The bottom is 12-18mm thick and the sides are thinner to save on wood cost. I wouldn't go thinner than 6mm though.
The measurements for the sides are in the pictures. Measure twice before you cut because mistakes cost money.
Step 2: Once Cut, Build It Up.
once the sides are cut you need to cut your middle sections. the width of your box is up to you and your requirements. mine are 30cm wide and I screwed the sides onto the outside edge of the thicker middle sections. this makes it stronger and it's easier to get a straight edge on a thinner piece of wood.
Make sure you use glue along the edges. Wood glue gives a huge amount of extra strength and you can mix a simple wood filler if you have any gaps. Mix saw dust with wood glue and fill any gaps because you want the bottom to be water proof.
Step 3: Prep for Painting
Once the box is together you need to get your sander out and sand the inside and edges of the box. This will make life easier when you paint the box.
Step 4: Painting
For waterproofing any project that will hold animals or fish the best product I have found is A1 Pond Paint from Antel. It is completely safe once dried and that is what makes it worth the money.
It is water based but sets like a resin. It's a two part paint so mix small batches at a time because it actually goes a long way. I have built two large grow beds for a large aquaponic system (Pictured above) and a few other bits and I still have about half a tin left.
You will need to seal the wood with the first coat then, once it is dry, sand it down lightly and apply a second coat. Once you are finished painting you can clean up with water.
Step 5: Finishing Touches
Once you have completed your second coat of paint and it has dried overnight, you need to cut your top strips which direct the mature maggots towards your hole. Once these have been screwed into place you will need to cut a 1" hole in the middle of the V.
Now mix a tiny bit of paint and paint the strips and the hole. I used my excess to paint the front of the box but that's not needed.
Lastly you need to place a small hook under the hole you made. You will hand a small bucket under the hole which will be half full of flour. The maggots then fall from the hole and into the bucket. The flour dries the maggots out which stops them from climbing our of the bucket. When you want to collect your maggots you just put the flour through a sieve that leaves you with just maggots to feed to your fish or other pets.
You can also make a lid for the box to make sure that the maggots all go up the ramp. It also helps because maggots don't like light.
I hope you enjoy building the fly Box and keep an eye out for my next project which is a fly breeding cage that allows you to breed Black Soldier Flies in the UK even in winter. It is a much bigger job but I hope that it will make sense in the long run in savings on fish food and cutting down your carbon footprint while not relying on the sea for fish protein.
Any questions, just ask.
Step 6: What the Box Looks Like Now! Lessons Learned.
As you can see, the box is mostly full. It currently plays host to over 100 000 maggots and I only take 2/3rds of the maggots out as fish feed. The rest are allowed to pupate, breed and reproduce.
One real issue was a lack of food waste for the maggots to eat, so, I now add dry oats whenever I have not got enough food for the maggots. Mix it with a little water and they consume it like crazy. It adds to the yield too.
As you can see, I was forced to place a rim around the entire box. I did this because maggots that climb out of the muck are able to climb the sides of the bin. The rim creates a 2.5cm overhang that stops the maggots and forces them all to use the ramp. I chose to leave the rim unpainted because they would be able to climb a gloss Finnish. This doesn't mean that you can get away without painting the rest of the box. Without the A1 pond paint the wood would rot and the bottom of the box would leak.
The maggots prefer a moist environment so I add a bucket of water to the muck every few days. This raises the humidity which leads to a higher % of eggs hatching. Just don't completely flood the box, the maggots don't do well under water.
Hope you all enjoy making this and if you have any questions, please ask.