Building a small scale fly farm to process food and garden waste into high quality food for fish, lizzards and chickens. The maggots also make great bait for fishing.
You Will Need..
Large bucket with lid.
1x 3cm screw
1m of 1" black pipe
1.5" hole saw (For uniseal hole).
15cm of 1" pipe
1x 1" T piece
1x 1" 90° elbow
20cm of wire
Corrugated cardboard (any box)
Small bucket with handle
5L of expanded clay balls
Water butt tap
1mm drill bit
Water butt sized drill bit
This is for the advanced level box but you can make it much more straight forward.
To build a successful fly box you will need to understand a little bit about flies and maggots.
1. Normal flies are not bad but if you can get hold of Black Soldier Flies (BSF) your bin will be much more efficient and the maggots produced will be massive. BSF larvae are the most efficient maggots you will ever find. They also eat a wider range of waste than normal British flies.
2. BSFs are unique in that they are not attracted to humans when in fly form. They have no mouth parts so they don't go looking for food. After pupation they do nothing but find a mate and lay eggs.
3. The limiting factor with BSFs is that they are native to South Africa so they require warm, bright weather in order to mate. If you choose to produce them and want to do so all year then you will need to provide a warm environment with subsidised light.
4. Most maggots will eat non stop until they are ready to pupate. When this happens they purge their system's and then climb out of the muck in search of a dry place to burrow and then pupate.
Step 1: Choosing Your Bucket and Fitting Your Exit Pipe.
When choosing your container for your fly box, you need to consider how much food waste you produce.
My first bin was made from an old fish pond filter. It was square and had 2 existing holes. I used one as my exit and taped over the other. This was not ideal because the ducktape soon pealed off and I had maggots climbing out both holes.
The new bin is bigger and round. I chose it because it will allow me to dispose of all of my household waste. The lid is very important. The new bin said that it's lid was tight but ideally it would have been water tight. This is because the maggots are amazingly good at squeezing through tight spaces so if your lid does not seal then you will have maggots climbing out all round your bin.
Once you have chosen your bucket, bin or box, you will need to drill a hole for a 1" uniseal. This is your exit pipe hole. If the box seals well then you will have all of the maggots come out of this pipe when they are ready to pupate.
Step 2: Fitting the Exit Pipe
Once drilled you need to insert your uniseal into the hole and insert your pipe. I used a 1" pipe but you can go bigger if you want.
If you don't have access to a uniseal then you can use a bulkhead fitting. if that is also not possible then you can drill a hole that offers a tight fit around your pipe and silicone around the pipe to hold it in and prevent maggots escaping down the sides.
Be careful when inserting your pipe into the uniseal, if you put too much pressure on the plastic it could crack. I use silicone as a lubricant and I place my palm on the other side of the uniseal to apply pressure so I'm not putting any pressure on the plastic container.
Step 3: Installing the Maggot Motorway.
Like I said in the intro, the maggots will leave the muck in order to find a dry place to pupate. When wet, the maggots can climb the sides of the bucket. We don't want the maggots finding other ways out, so we install this ramp. The ramp is a pipe that is cut and turned into a gutter shape. The pipe should start at the one side of the T piece then go along the side of the bin all the way to the bottom where it wraps around the bottom and goes back up the bin to the other side of the T piece.
This provides an unbroken gutter which means that wherever the maggot gets onto the "motorway" it will always make its way up to the exit.
I found that you can easily attach the gutter to the T piece by leaving the gutter quite deep at the end and zip tying it to the outside of the T piece.
Step 4: The Drain.
The byproducts of breaking down the food waste are a rich compost and a liquid. The liquid quickly builds up and the maggots don't like to be submerged for long periods. So to fix this you need a way to drain the bin and prevent excessive buildup of the liquid. Some people drill holes in the bottom of the container but I don't agree with that. The liquid will smell if left on the floor and you will have no way of collecting it for use as a fertiliser.
Instead, I fit a water butt tap at the bottom of the bin. This allows me to collect the liquid and either dispose of it or use it as a fertiliser. If you want to use it as a fertiliser then you need to dilute it A LOT. A 50 to 1 mix is about right if you don't want to burn your plants.
Step 5: Liquid Buffer Space.
This is simple.
You don't want the maggots to drown but you don't want to have to drain the bucket every 5min. So I recommend a layer of expanded clay balls at the bottom. This gives the liquid somewhere to go and it allows you to drain the liquid without blocking the water butt tap.
My layer is 2-5cm deep.
Step 6: Finishing Touches.
Now that the box is together you only have a couple of things to do.
First you put a 90° elbow onto the pipe on the outside of the bucket.
Now drill a small hole in the top of the elbow and screw in a screw. This will hold your collection bucket in place.
Your collection bucket will need to be half full of flour. This gives the maggots a place to burrow and it dries them out and prevents them from climbing out of the bucket.
Black Soldier Flies are fussy about where they lay eggs. It needs to be dry and very close to food. You also want the ability to move the next generation of eggs into a new bucket or a tray while you clean the processed waste/compost out of the full bin. So, attach a clothes peg to some wire and suspend it above the food. I attached it to the T piece using screws.
Your other option which I personally prefer is to have a small tray with a little but if muck in it. You have the cardboard near that so you can choose when to put the new maggots into the system. This also lets you keep the lid on the main bin which cuts down on smell and the maggots really prefer the dark so eat more and grow faster.
Step 7: Attracting Flies.
Now that your bucket is built you need to add some food waste. If you are going for British flies the your best bet is a small piece of meat, maybe left over chicken bones. It won't take long for the flies to arrive. Once they have found the bin you will see small clusters of eggs. Soon it will be crawling with maggots and you can add more food waste.
Garden waste is difficult because the maggots won't eat cut grass and other things so read up on what garden waste they will eat.
After a few days you will see that maggots are in your harvest bin buried in the flour. All you need is a sieve to separate the maggots.
Now you can feed the majority of them to your pets. Leave some to pupate and become the next generation of adult flies.
You may want to place your bin on a tray. My lid is not tight fitting so I have maggots falling out the sides of the bin. So I put it on a garden tray which I covered in flour. Now I just sieve that flour too and I have more maggots for my fish..
I hope this is a helpful instructable and I hope you enjoy building it.
If you want to try BSF larvae then you can buy them on eBay. They are also called "calci worms". (I don't sell them)
Step 8: Ways to Improve the System.
I am planning on building a cage for the flies. This will keep all the flies inside the frame and I can add insulation for winter.
To provide heat and light i will use a 250w HID lamp.
I have 200 trout in my aquaponic system and I like to recycle the family food waste to make food for my fish.
I am currently producing 500ml of maggots each day.
I purchased 1000 BSFs and they have all made it to pupation so I am hoping for a few hot, bright days to allow the BSFs to mate and multiply.
This is the most natural way to both dispose of your food waste and to produce a regular supply of high protein food for your pets. I prefer it to commercial fish food because it takes an average of feeding 1.5kg of fish meal (sea fish) to produce 1kg of fish in captivity. That can not be allowed to continue! This is the natural answer to a sustainable fish production. It can also be up scaled!
Thanks for reading!