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

12 Things to consider when choosing a composter

12 Things to Consider when Choosing a Composter

1. What is it you hate about composting?

a.  The time it takes to manage some composters – and/or it’s a chore
b.  The smell some composters produce
c.  The difficulty with getting the right nitrogen/carbon mix
d.  Don’t like big composters taking up space or being visible in the garden
e.  The vermin they attract – flies and rats or snakes nesting inside them
f.  The continuous cost of an extra product to make some composters work

2. What do you want to achieve by composting?
Or – What do you like about Composting.

a.  Produce soil to use for growing veggies and ornamental plants
b.  Don’t want to use fertilizers in your garden
c.  Prefer a more organic system
d.  Want to help the environment
e.  Just want good soil in your backyard
f.  Hate throwing your waste in the council bin or
g.  Storing overnight in a freezer
h.  Hate smelly council bins

3.  What do you want to compost?

a.  All your kitchen or just some of it.
b.  Worm friendly waste only
c.  Garden waste, green waste, grass clippings, weeds etc
d.  Animal excrement – dog and cat poo in particular
e.  Farm animal waste

4.  Do you have animals that get a portion or all of your waste?

a.  Chickens / Ducks / Geese / Guinea Pigs / Rabbits
b.  Horses / Cows / Goats / Pigs / Sheep
c.  Dogs / Cats
d.  Wildlife – Bandicoots / Foxes / Busk Turkeys / Antechinus

5.  How much time do you have to compost?

a.  Your time is your own – unlimited (retired perhaps)
b.  You have some time but prefer to use it for gardening or other activities
c.  You are too busy to compost
d.  You have children that can do it for you

6.  Do you grow or want to grow vegetables?

a.  You want to grow your own vegetables
b.  You already grow your own vegetables
c.  You want to teach the kids how to grow their own vegetables
d.  You have not had much success with propagating and growing your own food

7. Your physical fitness?

a.  Back problems – Can’t lift heavy weights Can’t bend down
b.  Disabilities – wheelchair bound
c.  Age
d.  General health

8. Size of your property?

a.  Farmland – unfenced / fenced
b.  Large / small urban block
c.  Courtyard
d.  Unit / Balcony
e.  Other

9. How many people in your household?

a.  One person
b.  Two people
c.  A family of three to five
d.  A family of five to ten
f.  More

10. How much waste do you produce?

a.  One bucket full a day
b.  One bucket full every 2 to 3 days
c.  One bucket full once a week
d.  One bucket full every two weeks
e.  More than one bucket a day

11. What is your climate like?

a.  Temperate
b.  Tropical
c.  Sub-Tropical
d.  Cold
e.  Arctic.  You live in the snow perhaps
f.  Desert. Hot and dry

12. What type of soil do you have?

a.  Normal
b.  Sandy / Sandy Loam
c.  Clay / Clay Loam
d.  Shale
e.  Introduced top soil
f.  Raised Garden Beds – a mixture

8 Different Methods of Composting

1.  Open air composting (hot /cold composting)


2. Direct Composting (trench or in-ground composting)


3. Tumbler composting (A form of hot composting)


4. Worm composting (Vermicomposting)


5. EMO composting (Bacteria composting)


6. Compot Composting (Combination Composting)


7. Commercial Composting


8. Mechanical Composting

Composting Horse Manure – BEWARE

you need to know where your horse food came from before you use horse poo in your compost or on your garden. It will certainly make you question where you get your horse poo from and what the horses were fed. A very eye opening read. ENJOY

Composting Horse Manure – BEWARE

horse droppings

Composting Horse Manure – BEWARE because you need to know where your horse food came from before you use horse poo in your compost or on your garden.
I was going to condense this article, but I think the full article will be better for you all to read. It will certainly make you question where you get your horse poo from and what the horses were fed. A very eye-opening read. ENJOY

Be careful you don’t get more than you bargain for

This is a great article taken from: -Town and Country Farmer. Jan/Feb 2016, Vol
33 No 1. Article Written by Wayne Jeffery

Ever since Ian and I struck the first blow in our veggie patch adventure one of our main objectives has been to improve the soil quality. Almost every crop seems to thrive in nutrient rich, friable, well-drained soil and when you start with a dry, rocky, dusty paddock you know it’s going to be a long haul.

Over the years we have worked hard on mulch collection and manure additions, especially in our poly tunnel glasshouse. This year we were particularly excited at the possibility of having home grown tomatoes as early as November. So, can you imagine the sheer shock, frustration and anger that we felt on finding out that we have been inadvertently poisoning the very plants we are trying to nurture?

Residual herbicides

man pushing wheelbarrow

Seriously! It turns out that the horse manure we have been collecting and mulching is laced with residual herbicides.

Now my gardening love affair with poo started way back on the family farm when dad and I used to clean out the neighbours chook sheds. We would shovel out the manure onto the trailer and then spread it around our apple trees. Dry, dusty, dirty work but great for the trees and at the right price!

Over the years the availability of chook poo has declined but around our area more and more properties seem to have bags of horse poo out. the front for sale. Ian and I arranged to leave a trailer at a nearby property and have it loaded with the mixture of rice hulls and horse manure when the stables were cleaned out. After a year of composting, how good would this stuff be for our soil? Tragically, we had never heard of Picloram or the Pyridne family of herbicides.

We had never heard of Clopyralid or Aminopyralid either. Nor nearly two hundred brand names of broad leaf herbicides.
Herbicides that can legally be used in hay and oat production. Herbicides that can end up in horse poo at levels lethal to a vast array of vegetables and flowering plants. Honestly, I can still barely believe it.

I was really keen to get our glasshouse tomatoes growing early this year. I purchased some advanced plants and planted them in beds freshly dug over with a healthy addition from our compost piles. Hard work but well worth it, or so I thought.

Growth was almost non-existent. “Told you it was too early”, grumbled Ian. Gradually there was some growth, but the plants became spindly with the leaves cupping and the tips curling. “Perhaps the rice hulls have leached all the nitrogen out”, mused Ian. “I knew we should have done a soil test”. Sadly, I knew it wasn’t just Ian being Captain Negator either. We also had plenty of other plants that weren’t flourishing.

Rich, friable, well-draining…. Poison?

As fate would have it, I’d planted quite a decent patch of potatoes and filled the trenches primarily with our mulch. Rich, friable, well-draining… Poison! The obviously mutated, twisted, fernlike growth of the potato leaves was the final pointer to our problem. So, with that evidence and a lengthy stint giving google a solid workout the scope and impact of this residual herbicide problem has now become apparent.

If you search the internet yourself (clopyralid horse poo will give you a solid starting point) you will find accounts of the problem from numerous American states, the UK and here in Australia. Instances dating back ten years or more but still occurring today. For those of us who love our gardens there are many cases that make for sombre reading. Commercial composters selling tainted compost, small farmers losing their livelihood. I’m still wavering somewhere between outrage and depression at the situation.

3 Dangerous Herbicides

horse poo bags

I’ve added our compost to so many beds in the open paddock, no wonder the climbing beans are deformed, and the peas were a waste of time.

These herbicides can still have an effect on certain plants at levels as low as one part per billion! Tomatoes and potatoes are particularly susceptible, but the list also includes sunflowers, carrots, eggplants, peppers and many more.

Apparently, most chemicals break down quickly in the composting process. Unfortunately, Picloram, Clopyralid and Aminopyralid don’t. They are easily absorbed by unaffected plants (hay and oats) and remain chemically stable and intact through an animal’s digestive system and contaminate manure, urine and stable beds. Just imagine how much tainted urine our rice hulls have soaked up. Argh!

And what a crazy state of affairs. Sure, the herbicide labels have a warning on them. Something along the lines of “Do not apply to crops that will be used for the production of compost or mulch. Such Compost or mulch made from treated plant material may cause damage to susceptible crops and plants!’ Great. Where’s the warning on the hay? The oats? Or most importantly, the manure?

What a Nightmare!

potato plant

“Some healthy potato plant foliage on the left and our mutated, twisted, fernlike growth on the right.”

Rectification of the problem has been hard, depressing work. And it’s not over yet.

All the soil in our glasshouse has now been wheelbarrowed out and replaced but throughout the patch there remains pockets of mulch, harbouring its toxins ready to nobble our next planting. Constant working of the soil is said to help leach the chemicals out but with the nasties operating at such tiny concentrations it’s hard to be optimistic.

I’m quite surprised that I’ve never come across this problem before. I’ve been warned about importing weeds to the garden by applying manures without composting them but not this disastrous situation.

Imagine how many people have been left scratching their heads wondering why their garden was struggling. I guess the best we can do is to warn others of the problem and source our manures carefully. If the horse owner doesn’t know the history of their horse feed then the manure just isn’t worth the risk. Believe me. We sure found out the hard way.

A solution to the problem

activated charcoal

Foot note from Vicki: I have a customer who lives near horse stables attached to a racetrack. She used to collect all the horse manure for the stables, and she ended up with the exact same problem in her garden. The only way she could rectify the problem was to load up the garden with activated charcoal. Activated charcoal absorbs the harmful chemicals and keeps them locked inside the charcoal. This was the only way she could fix the problem without ripping up her whole garden and replacing all the soil. So check what your horses are fed before you use their manure.