Composting with Black Soldier Flies

Composting with Black Soldier Flies

Composting with Black Soldier Flies

is way more efficient than many other methods of composting because you can feed them ALL kinds of biodegradable matter.

When I began composting with Black Soldier Flies inside the Compot back in 2009 there was very little information available online.   Most people in Australia had never heard of them.  Information is now readily available about composting with Black Soldier Flies.  Many companies now experiment with them for waste disposal and a protein-rich food source for animals.

Since launching the Compot in 2013, I have spent hundreds of hours speaking to people about using these special little critters as composters in a Compot.   Lots of people have found them in their worm farms.  Thinking they were house fly maggots they tried numerous methods of eradication only to find they’d reappear.

Once the Soldier Flies finds your worm farm it is difficult to eradicate them.  With a little effort and experimenting, you can find just the right spot in your garden where (for whatever reason) the Soldier Flies don’t go.  Some people are lucky but most aren’t.

Are they bad in a worm farm?

Composting with Black Soldier Flies in a worm farm is not ideal.   Using them above ground creates a foul odour.  And they will slowly crowd out your worms.  Or eat all the food leaving nothing for the worms.  Worms are self-regulating so will most likely eat each other at this point.

Plus the leachate the larvae produce is too acidic for the worms in the early stages of its decomposition.  The worms can’t escape from this is a worm farm.  In the ground, they will move away from the leachate until it is safe for them to consume it.

The Black Soldier Fly Larvae have been known to block the drain at the base of a worm farm causing worms to drown as the liquid can’t escape.   This requires a complete overhaul of your worm farm.  But don’t throw these little guys away.  Put them on your garden bed.  They will continue to decompose your waste or become food for garden critters.  Lizards, birds, chooks, and fish love them.  They make great bait for fishing enthusiasts.  This can be a smelly process.  Much easier to use a Compot.  But it does, of course, depend on your preferred method of waste disposal.

Black Soldier Flies are way more efficient at waste disposal than worms.  Try and find a way to make them work for you.

What does a Black Soldier Fly look like?

The mature fly is roughly the length of your thumbnail.   Long skinny and of course black.  In some countries, they can vary in colour.  Though they have no real mouth with which to eat food or bite you, they can suck up nectar or water to survive long enough to find a partner, mate and lay their eggs.   Unfortunately, they die after mating and egg laying. Such is the life of the Soldier Fly.

If you happen to find one in your house he has most likely lost his way.  Or you have something rotting in your kitchen that has attracted them.   They’re easy to catch and relocate outside the house.   It is best not to kill these little guys because they are so valuable for composting and waste disposal.   As there are so many of them it doesn’t really matter if one dies a little earlier than he should.  But better to just release them outside.

How do they lay their larvae?

The Black Soldier Fly has roughly 74 days to mate and lay their eggs.

After finding a mate the search begins for a suitable spot to lay their larvae. They don’t need to lay directly on the food source like house flies do.   They can lay anywhere near the food source and the larvae will find their way to the decomposing waste.

The picture above (captured by Mark) shows the Soldier Fly pushing his tail into the sugar cane mulch next to a Compot to lay its eggs.  Great shot Mark.

What do the Larvae look like?

Soldier Flies can lay anywhere from 400 to 800 baby larvae.   Incredible, coming from such a small creature.   Their larvae are so tiny they can get through the tiniest hole in your worm farm without you even noticing until it’s too late.

You will first notice them when they look like a little brown grain of rice or when they are big fat white larvae.   Both these stages show clearly the ridges that run around the body of the larvae.   One end tends to be tapered while the other end is blunt.   It is difficult to distinguish them from a blowfly maggot when larger unless the blowfly larvae are small.   Blowflies hatch in a day and at two days are roughly 4cm long whereas the Soldier Fly will look like a grain of rice.   From my experience, the Soldier Fly is fatter around the middle compared to the ordinary old fly larvae.  From my tests, it appears the blowfly larvae die when in a confined space with the Soldier Fly larvae.

In these early stages of the Soldier Flies life, when they are fat and white, they are good to feed to your chickens and fish.   I did try to feed them to some birds but they weren’t interested.   Mind you it could have been the fermented waste smell on them that deterred the birds even though I gave the larvae a rinse in water.

How long to the larvae live?

The larvae last for roughly 22 days depending on the weather and food availability.   If it gets too cold they can hibernate in the soil for up to 9 months.   But they are fussy when it comes to light.   They prefer it to be dark so if you have them inside your Compot and you can’t see them they are most likely hiding under a layer of waste to protect themselves from the light.

In perfect conditions, you will see them inside your Compot very easily without having to go digging for them.   But you will still know they are there even if you can’t see them because your waste will keep dropping down in height as they chow through everything so quickly.

Composting with Black Soldier Flies produces leachate which seeps out into the surrounding soil ready for your plants and worms to turn it into composted soil.   When you water your garden the leachate mixes with water to make nutrients available for your plants.   This also works well when you collect all your wastewater (without detergent)  along with your scraps and fill your Compot up with water and waste.  So you are not only saving water, but you are watering the garden at the same time and providing a solution for the leachate to mix with, which in turn provides nutrients for your plants.

How do they deter house flies?

If you watch the video at the beginning of this article about composting with Black Soldier Flies, you will see a container with some ham covered in house flies.  There are in fact heaps of Soldier Flies mixed in with this waste.   The blow flies are not deterred at this stage by the Soldier Flies.  But the Soldier Flies will take over the space and most likely eat the fly larvae.

In the above picture, you can see house flies trying to get out of the Compot. It is possible inside the Compot that the fermented smell of the food along with a fermone that the Soldier Fly produces, is enough to drive the flies crazy and scare them off.   You can see them desperately trying to get out through the holes in the lid of the Compot (in the video).

It is unusual to get house flies in your Compot but if you do don’t worry as they are part of the decomposition process and will die in there as they can’t find their way out.

Covering your Compot with a suitable cover will keep the hot air out in summer and the cold air out in winter plus prevent house flies from managing to find a way in.   If they are buzzing around your Compot you haven’t covered it properly. This is only necessary for the house flies and vinegar flies as the Soldier Fly will usually find your waste even with a covering on your Compot.

What do they look like in the prepupal stage?

When they are ready to change to a mature soldier fly they find their way out of the Compot and develop a hard black casing around their bodies.  It takes about 2 weeks to pupate and emerge as a mature Soldier Fly to start the process all over again.

Why is Composting with Black Soldier Flies so good?

  • It is fast, efficient, and no hassle
  • Soldier Flies are found almost everywhere but mostly in warm climates.
  • You can feed them anything biodegradable
  • Meat and fermented waste are one of their favorite foods
  • No special conditions are required for them to thrive
  • They love darkness when in their larval stage
  • Unlike the good old house fly, they don’t carry diseases
  • With no real mouth, they don’t bite or hang around your bar-b-q
  • Frass and leachate – is amazing fertilizer for your garden
  • They dispose of ALL your waste quicker than worms,
  • Even good for human and animal waste.
  • Maintenance is non-existent,  unlike a worm farm or tumbler
  • Go on holidays and they look after themselves
  • When used in a Compot they will reduce your council waste by over 50% because you can feed them ALL your kitchen waste including meat, dairy, citrus, onions, oil, egg shells, fish, prawns, paper towels,  absolutely anything bio-degradable.

If you find them in your garden be grateful. They are awesome.

Life cycle of the Black Soldier Fly.

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What Makes Good Compost?

What Makes Good Compost?

What Makes Good Compost?

Compost is the result of a successively staged natural oxidation process that transforms heterogeneous solid organic matter into a homogenous fine particle, called humus.

But how do you know it is good?

There are roughly 7 different elements required to make good compost:-

  1. Plenty of Organic Matter, for energy for the decomposing organisms
  2. Nutrients, especially Nitrogen
  3. Oxygen, (with a few commercial exceptions)
  4. Water, but not too much nor too little
  5. Cations, especially Calcium to stabilize the compost
  6. A suitable pH range
  7. Temperature

Most of us only follow a few standard rules when composting in our backyard.  These are:-

Carbon-Nitrogen Ratio

You usually start with a 30 -1 ratio of Carbon to Nitrogen.  The Carbon can be from any plant material that is shredded and small enough to increase its surface area for fungi & Bacteria to break it down into Compost.

This does NOT include any branches even though they are all Carbon.  They are too large and need to be ground down into a lot smaller pieces by a mulcher in order to compost them quickly and effectively.

Preferably you try to layer 4 inches of carbon to 3 inches of greens.

If you have too much carbon your pile will be dry and slow to break down.  Too much nitrogen your pile may well be a big slushy mess.

In time this will sort itself out if you can tolerate the smell.

But if you get this ratio wrong in your veggie garden and have too much carbon the microbes will take nitrogen from the soil making it unavailable for your plants.   That is why if you are making compost in a heap you should make sure it is fully decomposed before you place it around your plants.


Composting organisms REQUIRE moisture to be active otherwise they go into a resting stage called spores.  But the compost heap cannot be too wet or too dry so the organisms have an ideal environment to survive.

The heap may be too moist if the top is open & rain has saturated the heap.
Or too dry because it is too thin & drying out in the sun.  Or you have too much carbon in the mix.  There is a fine balance between being too wet or too dry that can take quite a bit of work to maintain.  Covering a moist compost heap with a tarp will keep in the moisture, keep excess water out, and make your heap break down quickly without requiring water all the time to keep it moist.


Air containing Oxygen must be mixed throughout the pile by turning the heap every 3 days.  When the outer layer of the compost that has cooled down it can be alternated with the inner hot layer.   This allows Oxygen to penetrate throughout the heap.  Without this constant turning, the heap will take a long time to break down.  It will get very hot in the center of the pile preventing quick break down by the microbes as they can only survive at a certain temperature.

Too much air can also dry out the heap dehydrating the contents rather than decomposing them.   Dehydrated contents make a mess in your garden if you are just tossing food waste on your garden bed.   They need to be reconstituted with water to allow for proper decomposition in order to be converted to good compost.

So don’t let your heap dry out.  This can be a tricky balance between being too wet or too dry.  One can’t work because it is too dry.  The other can’t work because it is too wet and often turns into a big stinky sludgy mess. This then requires carbon to soak up the water and decrease the smell.

So turning your pile regularly and maintaining the moisture at just the right balance will add the necessary oxygen and moisture to keep your compost heap functioning correctly.


It is not a good idea to add weed seeds to your compost heap unless the heat gets hot enough in the pile to destroy the seeds.  Nutgrass is a particular problem in the compost heap and can be spread around the garden when you distribute and dig the mature compost into your soil.

I have personally found, rather than removing the nutgrass, I cover them with grass clippings every time I mow the lawn. The nut grass appears to die out as it can’t find the sun to reproduce. This has been an effective control for me as I don’t have time to dig them up and dispose of them whether it be in a bin or in the compost.

Some people put seeds from food waste in their council bins rather than separate it for the compost pile. This is too much work for me. I find it easier just to remove unwanted seedlings like pumpkin vines as soon as they sprout in your garden. Unless of course, you don’t mind if they take over your garden.

This happened to me and the end result – though I did get some lovely pumpkins out of the patch – smothered other plants and virtually killed them. And when I was removing the whole plant I accidentally killed some plants when I cut the vine as they were so entangled together.

But it is a great way to grow things without having to purchase seeds. It is just something you need to be aware of when composting.

But do all these things make good compost?

Well, that all depends on the nutrients available in the compost at the end of the composting process.  Unfortunately, you can’t know exactly what nutrients are available without expensive testing and then you have to know what tests to ask for in order to know what is useful in that particular pile of compost.

On top of that, the nutrients shown in the test may not actually be available for the plant to use.  They might be tied up chemically and inaccessible to the plant.  Then the pH has to be right as well for the plants to access the nutrients.  The Ph is probably the most important factor that can be easily tested at home in your garden without the need for expensive soil tests.

For farming purposes, you must test your soil and/or compost to find out what is lacking in your soil in order to grow a particular crop.

But compost is one of the most important things to add to your soil as it stores and releases nutrients easier, holds water better, improves tillage, soil structure, and soil matrix.  A must for every gardener.

What should I add to make my compost better?

If you really want to go to all the trouble and expense of trying to produce perfect compost (very difficult) then in addition to the usual compost mix of grass clippings, small mulched branches, shredded leaves, some vegetable waste, and other garden waste, you could add these ingredients:-

Additional Ingredients to make good compost

  • Soil with a clay component – to hold nutrients and reduce nutrient loss
  • Gypsum – to add sulphur essential to activate the nutrients on soil particles
  • Rock Dust – can add up to 5%
  • Rock Phosphate – for phosphorous – up to 5%
  • Lime – a sprinkle unless the ph is too low.
  • Wood Ash – but not too much or it will raise your ph too high
  • Worm teas, comfrey teas, nettle teas
  • Sawdust, used hay, straw
  • Paper, Corn Stalks
  • Manures, Blood, and Bone

Basically, anything that is biodegradable as long as you keep that carbon-nitrogen balance, water balance, aeration, and Ph correct.

You can put meat products in your compost as long as you bury them deep enough to prevent rats and other vermin getting at them.  But this can be tricky.

I personally find putting a Compot into your compost pile makes disposing of all your kitchen waste, (especially meat products), super easy.  This way you can lock up your meat, dairy, eggs, and anything biodegradable inside your Compot inside your heap.    This improves the overall nutrient content of your compost.   It will bring the worms as well who in turn improve your compost nutrient mix.   Or plant a few Compots in your garden if you couldn’t be bothered with a compost heap, which generally speaking is a lot of hard work.

So what makes good compost?

In the end, don’t worry too much about your compost (unless it turns into a big smelly mess).  It is still the best way to nourish your plants, dispose of waste, and help the environment even though each particular batch may not be perfect.   But it does require large quantities of materials to produce a small amount of compost.   Understanding how all the elements in your soil and your compost interact with each other to produce great soil is a complex process that is even more complex to describe.

Basically, it comes down to always mixing as many different materials as you can in your compost heap.   This will ensure you have a pretty good chance of producing “good compost” that is nutrient rich to make your plants grow.

What not to put in your Compost heap?

Gum leaves, as well as Pine needles, contain a chemical that stops any other seed from growing under that tree. This means that particular tree can utilize all the available water and nutrients they need to grow and don’t have to share resources with other trees.   This is important because these trees are usually found in dry, nutrient-poor areas where there is likely to be competition for any available water and nutrients.

For this reason, Gum leaves & Pine needles should NOT be added to a compost heap.

Of course, there are all the other “usual” suspects that don’t work well in a worm farm or outdoor compost heaps such as Meat, Dairy, Eggs, Oil, Onions and any citrus waste.  But you can put all these items in a Compot if you own a Compot.
Bob James
Lovel,  H. 2014; Quantum Agriculture Biodynamics and Beyond;  Quantum Agriculture Publishers; 2014

8 Methods of Composting

8 Methods of Composting

8 Methods of Composting is what I consider to be the most commonly used methods of composting for a business or home environment.

If you have read 7 Composting Methods then this article is an update to that article.  I added Mechanical Composting as I think this is another very viable method of composting that like all composters have its own advantages and disadvantages.

For a deeper understanding of composting register to receive the monthly newsletter and you will be emailed the white paper by Bob’s James on Composting Principles which discuss the mechanics of composting.

The other information in this article talks about the different methods of composting.

Everybody has different needs so at any given point in time one or more of these methods might suit your current living conditions and you might at some point change the way you compost many times throughout your lifetime.

What you once found useful might become obsolete as your needs and environment change so it’s a good idea to have an understanding of the pros and cons of each system.  However, what might be a pro for you may be a con for someone else.  You just need to work out what is best for you.

They all work in varying degrees for different purposes, some more efficiently than others and some are just simply, different.   You may have tried some of these methods, are happy with your method, are looking for something to compliment your system or are looking for a change.

So I hope this information sheds some light on factors you may not have considered when you last chose your composter or if you are now choosing a new composter.

Composting Methods

Traditional backyard composting is typically achieved by:


Open air composting (hot composting)


Direct Composting (in-ground composting)

More Recent methods of composting are:


Tumbler Composting (A form of hot composting)


Worm Farm Composting (Vermicomposting)


EMO Composting (Bacteria composting)


Combination Composting (Compot Composting)


Commercial Composting


Mechanical Composting

Elements generally required in most systems in order to produce compost.

Air Compost needs to be aerated or it creates an anaerobic environment for bacteria which produces unpleasant odours and attracts vermin
Water Essential to keep the compost moist
Vegetable Matter Essential to obtain organically rich compost
Worms Digest decomposed matter and release worm castings that provide plants with the nutrients they need for growth
Carbon-nitrogen mix (brown and green waste) Essential to create the right temperature for creating compost from green waste and to kill seeds and disease
Bacteria (EMO’s) Will decompose the food before the worms eat it
Soldier Flies Not essential but devours waste food quicker than worms or bacteria
Other Beneficial Bugs Cockroaches and other insects that help in the decomposition process (including maggots if putting meat in a compost pile – not recommended for most composters except the Compot.

1.  Open Air Composting

Open Air Composting is traditionally a pile of green and brown matter in your backyard.

More often than not it is a bay constructed of anything you can get your hands on that is cheap and easy to put together.

Or you might have a couple of bins upturned sitting on the ground like the Gedye bin you can buy in a shop.

Wire cages are also used inlaid with piping around the edges to hold water and capture heat.

This can then be used for hot water systems in sustainability situations.

Open Air Composting is generally considered to be a Hot Composting method.  Some people often call it a Cold Composting when smaller quantities of waste are used because it does not build up the same amount of heat.

To me, Cold Composting still produces heat and therefore is not technically cold composting.

Perhaps one could call it Warm Composting as the only way you could completely cold compost something is to let it rot in the fridge.  And we all know that smell in the fridge.

Pros and Cons of Bay Composting

2.  Direct Composting

Direct Compost is simply digging a hole or trench in the ground and burying your scraps.

It is also probably the oldest and most effective method of composting, but like all other methods of composting it too has its limitations.    The main one being that it takes a long time to decompose unless you chop everything up.

You can only bury fruit and veg or you run the risk of it being dug up by all sorts of garden critters from birds to vermin.    And you have to keep digging holes.

It does, however, produce an abundance of worms that then help to nourish your garden and improve your soil.

Pros and Cons of Direct Composting

3.  Tumbler Composting

Tumbler Composting comes in many shapes and sizes of single to double units that you may purchase commercially from your local hardware store.

For many people, this is a great system if you are relatively strong and keen to turn it every day or every few days.

For others, it is hard work especially if you are getting on in years. But you can get some mechanized ones that make turning easier.

You often need two of these systems so you can let one sit for a few months to fully decompose before you empty it.     While this is happening you fill the other one up.

This can be a good system if you have a large amount of green and brown waste to dispose of and have the space to fit this system.

If you are only filling it with green and brown waste then a bay system would be just as good though you may have to watch out for snakes and rats nesting in the warm compost.

Pros and Cons of Tumbler Composting

4.  Worm Farm Composting

Worm Farm Composting for many is the most common and preferred choice of composting because of their capabilities to grow worms, produce compost and compost tea and keep rats out of your compost.

The worms produce castings concentrated with nutrients lower in nitrogen compared to other composting methods.

Worm farms can be utilized even if you have no garden.

I think everyone has tried at some point in time to make their own worm farm with varying degrees of success using anything they can find that is cheap.

Do not house them in metal containers as copper leaches out, which is toxic to your worms.

I personally have tried foam containers only to find the worm juice eats out the foam so they leak everywhere.

Unless you have them on the ground somewhere so the nutrients can go directly into the soil you end up with a big mess.

If you use plastic containers you can collect the juice but then you have to add a tap to drain it off or some way of rotating the containers to collect the worm tea.

They need to be kept out of the sun, frost, and rain, and somewhere that’s not too cold either.

Worms are temperamental little critters and will try and escape their containers if the conditions are not right and they are not happy.

It is said that you should use local worms for your area.    I personally have no experience with this so you would have to try worms from other areas to know for sure if they will survive.

Local Worm Types

  • South Australia Red Worms (Lumbricus rubellus) and Tiger worms (Eisenia fetida) under ideal conditions are said to rapidly reproduce 8 to 1500 worms
  • The Tropics use Pontoscolex corethrunus or Pheretima group, commonly found in gardens
  • Fishing worms are apparently not good for composting.

If you can be bothered (according to Bob) you need to test the pH of each batch as some may be are more acidic than others.

But who has time for this or could be bothered.

That’s why I love the Compot because the local worms in your garden will come and you don’t need to add worms unless you have really bad soil.

Pros and Cons of Worm Farm Composting

5.  EMO Composting

EMO Composting or Effective MicroOrganisms is a system generally used for indoor composting but can be used by anyone who likes this method of composting.

The most common product using EMO’s is the Bokashi but other indoor systems can use it plus there are some systems that use a carbon filter in the lid as well to filter odors.

Generally speaking, you need two of these, so while one is sitting the other is being filled.

You can collect juice to use in your garden.

But you cannot put everything from your kitchen is the Bokashi System.

You can buy the EMO online through many sites selling the Bokashi System.

You can use the EMO’s in other systems if you so desire to aid the composting process.

Pros and Cons of EMO Composting

6.  Combination Composting

Combination Composting or Compot Composting is a combination method of open-air composting, direct composting, vermicomposting, and EMO composting.

All the elements of composting are used and will suit most household circumstances.
For some people, it too has its challenges. But for me, the challenges are less and the rewards are better.
You can compost ‘ALL’ your kitchen waste and not just ‘some’ of it.

So ultimately you have over 50% less waste each week to put in your council bin.

Just Fill…Forget…Refill…when ready and give it a good clean out once a year.

It is faster and requires less work than most other composters.

And it nourishes your soil with all your own waste.

To me, it is the easiest composter I have ever used.

Pros and Cons of Compot Composting

7.  Commercial Composting

Commercial Composting is different to backyard composting and uses different materials.
The Compost is made in long rows using such materials as, sawdust, pine bark, sand plus ferrous sulphate and maybe some sulphate of ammonia all mixed together.
It is usually turned every 3 to 4 days and is generally ready in 6 weeks for bagging.
There is not much nutrient value in the cheap commercial compost.
But there are small independent commercial compost companies that produce a better quality product, than the large commercial compost companies.   They are however more expensive.

Some producers such as McLeod’s Agriculture are certified organic as well.
The old saying “you get what you pay for” certainly applies to commercial compost.

The cheaper commercial compost is a good filler for raised garden beds or to backfill a Compot in clay or sandy soil.

Or it can be used to mix with composted soil to fill a pot plant perhaps.
If you are buying commercial grade compost to grow things it is best to buy a high-quality propagation mix.

Pros and Cons of Commercial Composting

8. Mechanical Composting

Mechanical Composting is an efficient method of composting that uses electricity to create the heat required and rotation of the contents required to produce semi-composted waste literally within a 24 hour period.

This system suits restaurants, hotels, motels, hospitals, schools, kindergartens and any large institution creating large amounts of waste from many people.     It is a manageable in-house system instead of sending your waste off to council tips.   You do however need to further compost the waste so need someone to collect the leftover contents for further composting in a garden bed or bay composting system.

There are also small systems that suit some people for their private residence but they can be quite expensive and will, of course, cost you ongoing electricity.  Like all composters they to come with some pros and cons, but they do produce fast semi-composted soil.

Pros and Cons of Mechanical Composting

In closing…

8 methods of composting is a guide to a number of composting methods that you might want to consider using in your home or business.

Some are similar, some are the same, some work better as a combination and some are just different.   Either way composting is still the best thing you can do for your business,  your garden, and the environment.

Much of the damaging effects to the environment comes from the methane produced in large council tips.  Methane is worse than co2 for the environment.    Keeping your waste out of the council tips reduces methane waste and ultimately helps the environment.

If you have time to grow your own veggies and utilize your compost then that is an added bonus.

Ideally, we all should play our part in reducing council waste.

How you do it is up to you, but whatever method you choose –  doing something is better than nothing.