What Do Black Soldier Fly Larvae Eat?

In this article, let us look at what you can feed the feeders: what do black soldier fly larvae eat? We cover various types of organic matter that you can feed your BSFLs.

Black soldier fly larvae are a great way of turning food scraps and other agricultural waste into high-quality compost. 

The insects, as a by-product, can be further turned into chicken feed or poultry food. 

Being a great food source and efficient compost producer, they are largely used in food waste management and the animal food industry to break down organic wastes. 

They are also certified for human consumption as a source of protein –  though they’re yet to be viewed as a common food source by the general public. 

Let’s take a look at how the larvae are reared, fed, and used for this purpose. 

What Do Black Soldier Fly Larvae Eat
Black Soldier Fly Larvae

What Do Black Soldier Flies Eat in Nature? 

Black soldier flies help with decomposition and, hence, thrive on decaying organic matter. 

This includes all types of kitchen scraps, dying vegetation, fruits, vegetables, manure, and even animal carcasses. 

In fact, they help with the decomposition of some particularly difficult agricultural waste materials, such as rice straws. 

Rice straws have high lignocellulosic matter but are too low quality for feeding livestock. BSFL (black soldier fly larvae) helps to valorize these into compost. 

Due to their ability to eat almost anything, it’s easy to rear black soldier flies. 

There are many low-cost CORS (Conversion of Organic Refuse by Saprophages) systems that utilize BSFL for producing compost. 

Industrial-level BSFL-rearing facilities also exist, but these are governed by various laws regarding treatment and quality standards. 

Best Nutritional Content For BSFL 

Despite the ability of BSFL to break down any organic matter, what they feed on defines how nutritious the larvae are. 

This is especially important if one plans on using the larvae later on as fish or livestock feed.

This is because, if fed on toxic waste or exposed to biohazards and heavy metals, the larvae can retain these substances within their system. 

When consumed by livestock, the toxins get introduced into the food chain – resulting in a hard-to-break cycle. 

Currently, Hermetia illucens, or BSFL, is one of the seven recognized insect species that can be used for compost treatment and animal food. 

Black Soldier Fly Larvae

Some Union laws for the best nutritional content to be fed to BSFL are:

  • BSFL should only be fed contents that are non-animal in nature of origin. This means they can mainly feed on vegetative matter. 
  • Some animal products such as honey, eggs, fishmeal, and gelatin are allowed – but only leftovers from human consumption (as these have been treated and blacked). Animal manure, human waste, or flesh is not on the list. This is to prevent the introduction of potential pathogens in the BSFL. 
  • The feed given to them should contain at least 34% crude protein and 32% fat. 

When composting locally, farmers do not follow these rules. Chicken manure and fish intestines are very common BSFL feeds within the US. 

What to Feed Your BSFLs When Raising Them as Feeders

If you’re raiding BSFL by yourself, providing them with a varied diet is paramount. 

A good diet also helps with quick development and a more efficient breakdown rate. 

Besides, it creates healthy, nutritious larvae for your livestock to feed on. Here’s what you can feed them:

Food waste (Leftovers)

Any leftover food, both cooked and uncooked, is a good food source for BSFL. 

Human-grade food is also free from pathogens and potential contaminants, which makes it ideal for BSFL to feed on. 

It will eliminate any worry on your end about further affecting your livestock. 

Rotten fruits and vegetables

Rotten fruits and vegetables are a close second addition to the BSFL compost pile. 

Generally, if something starts decaying, it means there is significant bacterial growth, – and it’s best to provide the food to the BSFL before decomposition sets in. 

However, they can still consume decaying fruits. 

Black Soldier Fly Larvae

In fact, you also need to monitor your compost pile to ensure that the BSFL is able to decompose the food added every day before you add new amounts. 

BSFL compost does not smell – so if you do smell decay, it means you need to reduce the amount of food added every day. Or add more BSFL. 

Corn, soybeans, and other waste

Corn and soybeans are high in fat content and great food sources for the BSFL to break down and absorb. 

In the wild, BSFL tends to colonize these harder foods (and fruit rinds) naturally since they’re hard and form effective ovipositor traps. 

In other news, BSFL can actually fully replace any soybean-based diet fed to chickens. 

Fish waste

Fish waste can be a potential feeding item for BSFL – though it’s usually suggested to give them fish feed instead. 

And especially the ones used for non-salmonid species. The only downside to using fish waste is that it can introduce potential pathogens – if your fish was carrying them. 

Usually, farmers feed them fish intestines. You can also add whole fish since BSFL can break down bones.

Poultry manure

Chicken feed and poultry manure can be used if you are rearing BSFL locally. Industries do not use any form of manure due to pathogen introduction. 

We’ve discussed how to mix manure next. 

Black Soldier Fly Larvae

Animal manure

BSF naturally lays eggs in animal manure since it provides a rich substrate for the larvae to feed on. 

In fact, it’s best to create a manure mixture that contains 40% swine manure mixed with dog food. 

Or you could consider 50% kitchen waste mixed with chicken manure and some coarse minerals or coffee grounds. 

Coffee grounds waste disposal

Coffee grounds help boost metabolism but should be used as a sprinkle rather than an actual item. 

BSFL can survive fully on coffee grounds for a few weeks – however, the grounds in themselves do not have enough nutritional value to produce high-quality larvae and pupa. 

Cashew fruit

When cashews are harvested, 90% of the fruit is thrown away – with only the nut being used. 

The cashew fruit is being increasingly used as BSFL feed by many farmers. 

It contains sugar, amino acids, and vitamin C and is an efficient way of reducing the waste from cashew harvesting. 

Do You Need to Give BSFL Water? 

BSFL needs a certain amount of moisture content to thrive. Too dry, and they can shrivel, whereas too much water content can drown them. 

You can use a lid on the compost pile to maintain the humidity, along with a sensor. 

BSFL do not need water separately, as there is enough water content in most organic matter for them to survive on. 

If the feed is too dry (or consists of low water content items such as bones), you can spray some water onto the surface. 

For manure, you can consider adding it as a paste rather than as it is. 

Frequently Asked Questions

What can I feed my black soldier fly larvae?

When raising BSFL as feeders, it is important to provide them with a varied diet for quick development and efficient breakdown.
Leftover food, both cooked and uncooked, is a good source of BSFL and eliminates worry about pathogens.
Rotten fruits and vegetables are also good additions but need to be monitored to ensure decomposition does not set in.
Corn, soybeans, and fish waste are also high in fat content and great food sources for BSFL. Poultry and animal manure are also options, but they need to be mixed properly.
Coffee grounds can be used as a sprinkle but do not provide enough nutritional value.
Cashew fruit is also an efficient way of reducing waste and contains sugar, amino acids, and vitamin C.

Will black soldier fly larvae eat meat?

Yes, they can eat meat as well. BSFL are voracious eaters. They can consume a wide variety of organic matter, which includes meat. 
They also eat rotting fruits, vegetables, and even pet waste.
In fact, the larvae are used in waste management systems to convert them into compost.
Note that all types of meat are not suitable for them. Raw meat can contain harmful bacteria, which could be passed on to the larvae. 
This, in turn, would end up in the animals or birds that consume the BSFL.
Cooked meat, even if it is rotting, is generally safe to feed to the larvae as long as it is free of seasonings and sauces.

Do black soldier fly larvae eat leaves?

Yes, BSFL can eat leaves as well. They are voracious eaters, and won’t mind eating dried leaves and other organic and plant waste.
BSFLs are often used in waste management and composting systems. They are able to quickly break down organic matter into nutrient-rich compost.
They are also great as feeders for animals, and in some cases, they have also been considered for human consumption.

How do you keep black soldier fly larvae alive?

The life cycle and growth of black soldier flies are affected by several factors.
Sunlight is important for proper mating, survival, and growth, so artificial light can help increase their population.
Moisture content should be maintained at 40-60% for larvae survival, and pH should be above 6 for ideal larval development.
Temperature and humidity affect the entire life cycle, with adults living longer at intermediate temperatures.
Larvae can live and grow on alkaline substrates with pH values ranging from 8 to 8.5.

Wrap Up 

The consumption rate of the larvae is incredible, and each one consumes multiple times its body weight every single day. 

It’s best to provide a balanced diet for optimal larval growth. 

Using them allows farms to become more sustainable by recycling their kitchen and animal waste. 

BSFL are even being shipped now, packed within bales of hay and food items from proper rearing industries. 

Since they survive in most climates (unless it’s extremely cold) – it’s no wonder they’re becoming a popular decomposer insect. 

Thank you for reading. 

Reader Emails

Due to the rise in interest in organic composting and insect farming, we receive several questions from our readers regarding how to raise Black Soldier Flies. 

Some of these questions are listed below. Do take a look, as it might help add to your knowledge about rearing these insects.

Letter 1 – The Thing from Missouri is possibly a Soldier Fly Larva

 

have you seen one of these?
attached is a odd bug we found out walking in Missouri, we have never seen one before, wondered if you knew what it is?
jamy

Hi Jamy,
This was new to us, but we suspected some type of Aquatic Fly larva. Eric Eaton confirmed our suspicion: “Ok, I am pretty sure this is the larva of a soldier fly of some kind (family Stratiomyidae), and the “ovipositor” is actually a breathing tube. This thing should have been found in an aquatic, or at least very soggy, environment. In any event, it is most certainly a fly larva of some sort. Eric”

Letter 2 – Soldier Fly Perhaps

 

Unknown Green Fly
This picture taken 2007-09-19 in Kenner (near New Orleans), Louisiana. I have used you site and information but I have been unable to identify this fly. Any help would be greatly appreciated.
Ron M

Hi Ron,
Your fly resembles a species of Soldier Fly pictured on BugGuide, Hedriodiscus binotatus. We are guessing that it is either the same species or something closely related. We hope to get confirmation from Eric Eaton.

Correction
(09/23/2007)
Dear Daniel,
the green fly is more likely Odontomyia cincta. http://bugguide.net/node/view/53711 But the whole group of Odontomyia, etc is very difficult and there are many open questions and a revision of these beautiful flies is needed. It might be strange for you that I can ID an unusual Australian fly, but that I have problems with a common US species… but there has been not enough good work here and amongst specialist, we think that only 30% of all US Diptera are described… So a lot to do in future… You have a great website and I would love to help you ou with identifications in future! Best wishes,
Martin

Letter 3 – Black Soldier Fly

 

possible Black Soldier Fly
Hi. I’ve recently moved to a rural setting in Grady county in SW Georgia and I’m surrounded by all types of critters which are new to me. I ask for help verifying an insect as a Black Soldier Fly because I’m considering enlisting them in composting household food waste. The more I read about BSF the more I appreciate them. I’m curious what you’re feelings are about “using” an bug like this. Here is a link to a company which will soon be marketing a device for just that purpose. http://www.esrint.com/Bio.html The photo “possibleblacksolierfly” was taken in a house. The others were taken outdoors on food scraps. Thanks for the great website,
Jerry.

Hi Jerry,
Yes, this is a Black Soldier Fly, Hermetia illucens. The white tarsi or legs, which are especially noticeable on the window photo, are a distinguishing feature. Though we know nothing about the product you mention, we would fully endorse if if it worked. Keeping the fly population going might be a problem.

Letter 4 – Soldier Fly we believe

 

Subject: Bugs in Garden
Location: Detroit, Michigan
June 27, 2014 8:10 am
Hello, I am from Detroit, Michigan and there are at least 100 of these bugs in my organic garden of all different sizes. The larger sized bug seems to have more color but move much faster, I have a pretty big yard but they are only in the garden. Just trying to figure out what they are, I looked through the internet but cannot seem to identify them. June 27, 2014.
Signature: Alicia

Probably Soldier Fly
Probably Soldier Fly

Hi Alicia,
Your image lacks the necessary detail to be certain, but this appears to be a Soldier Fly, possibly
Ptecticus trivittatus which is pictured on BugGuide.  According to the Soldier Fly family Stratiomyidae page on BugGuide:  “Larvae in a variety of situations, but mostly associated with decaying plant matter from leaf litter to rotting fruits” which causes us to surmise that they are being attracted to the organic compost in your garden.  They will not harm your produce.

Looks like that is it! Thank you,

Letter 5 – Soldier Fly: Odontomyia cincta

 

Subject: Daniel – Syrphid Fly?
Location: Hawthorne, CA
August 5, 2014 8:16 am
Hi,
We have a new to us plant that came up this year – a Brown-Eyed Susan. It’s attracting all kinds of neat bugs and I got these shots yesterday. I’m sure it’s a Syrphid Fly and I know they are hard to pin down exactly because there are so many of them, but would you please be able to confirm and maybe find which one it is?
Signature: Thanks, Anna Carreon

Soldier Fly
Soldier Fly

Dear Anna,
We just went through all the Syrphid Flies twice in a feeble attempt to identify a “Corn Tassle Fly” sent to us from Indiana, so we were pretty certain your guess that this is a member of the family Syrphidae was incorrect, even though it greatly resembles the members of that family.  Our initial impulse that this is a Soldier Fly in the family Stratiomyidae proved to be correct.  We quickly identified your pretty Soldier Fly as
Odontomyia cincta thanks to this image on BugGuide which is a perfect match to your lateral view.

Odontomyia cincta:  Lateral View
Odontomyia cincta: Lateral View

Sadly, BugGuide has no species information, but we did learn on the genus page on BugGuide that we might have the species wrong because Species identification often requires examination of genitalia.”  BugGuide also notes the habitat is:  “Woodlands, fields, usually near water; larvae are aquatic” and “Adults take nectar, also sometimes found on dung; larvae feed on algae.”  We are guessing that you must have a water feature in your garden, or nearby.  Composite flowers, like this Black Eyed Susan and the Cosmos you grow are excellent for attracting pollinating insects like bees, wasps, beneficial flies and butterflies.  Alas, we only have four cosmos plants, and all are less than 18 inches tall right now.  None has bloomed yet.  The dry winter was not good for our normally very prolific garden.

Soldier Fly
Soldier Fly

Dear Daniel,
Thanks so much for the response.  I think you are correct, but the markings on mine are different than the photo of the Soldier Fly you linked to.
We have only a bird bath and small buckets of water (that algae grows in) that we put the legs to our worm composter in and then float mineral water on top of to keep the ants out of the composter.  Our neighbor to the south does have a pool that he doesn’t maintain very well . . .  I’m sorry to hear that your cosmos plants didn’t do well.  We’ve had only scattered blooms ourselves.  I think we’re a bit closer to the equator than you (joke) so may have had more rain.  Would you like to try your hand at scattering some Brown-eyed Susan seeds next spring?
Thanks again,
Anna

Thanks Anna,
Rudbeckia has naturalized in our yard, and some years there are more and some years less.  this year it is less, but hopefully seeds will drop.
Perhaps your Soldier Fly is a different species in the genus.  Alas, we do not have the necessary credentials to inspect the genitalia.

 

Letter 6 – Wingless Soldier Fly in the subfamily Chiromyzinae from Australia

 

What is this bug? Is it dangerous?
Location: Katoomba, NSW, Australia
April 20, 2012 5:40 am
We’ve been finding these bugs all over outside and my little boy has been playing with them. I just need to make sure they are not dangerous since they are all over the place lately.
Signature: -Autumn and Mark

Wingless Fly: Chiromyzinae species

Dear Autumn and Mark,
In January 2007 we received a similar photo from Australia.  We knew the creature was a fly, but we were uncertain if it was wingless or if the wings were somehow lost.  We eventually learned it was a wingless female fly in the Soldier Fly subfamily Chiromyzinae.  At that time, there was no information available on the internet.  Now we located a Tree of Life web page posted in 2008 that states:  “Chiromyzinae is an unusual group of soldier flies as the larvae are predominantly phytophagous, with many species feeding on the roots of grasses (James 1981; Oosterbroek 1998).”  These wingless Soldier Flies are harmless.

Letter 7 – Flightless Female Soldier Fly from Australia

 

Subject: unknown bug species
Location: melbourne, Victoria, Australia
May 12, 2015 1:20 am
Hi,
I’m wondering what this insect is. I have found several outside my house. Do they fly? Are they harmful? What are they?
Regards,
Signature: Sharon

Flightless female Soldier Fly
Flightless female Soldier Fly

Dear Sharon,
Your unusual insect is
Boreoides subulatus, a flightless female Soldier Fly in the family Stratiomyidae, subfamily Chiromyzinae, and the last image we posted of this unusual insect was allegedly sighted in the UK.

Thank you so much for getting back to me. Very interesting.
Warm regards,
Sharon

Letter 8 – Wingless Female Soldier Fly from Australia: Boreoides subulatus

 

Subject: Wingless soldier fly
Location: Sodwalls, NSW Australia
April 10, 2016 3:45 pm
Thank you for your reply to my query about how to add photos. Here is a photo of the bug which l finally identified as boreoides subulatus.
Signature: Elizabeth

Wingless Female Soldier Fly: Boreoides subulatus
Wingless Female Soldier Fly: Boreoides subulatus

Dear Elizabeth,
Thanks so much for submitting your high quality image of a flightless female Soldier Fly from Australia,
Boreoides subulatus.  The first time we received an image of this species, it created quite a stir in our offices. 

Letter 9 – Flightless Female Soldier Fly from Australia

 

Subject: Ident request
Location: 33°43′S 150°20′E
December 2, 2016 7:19 pm
David,
2 years ago I was in Leura, a small town in the Blue Mountains just west of Sydney Australia, when I saw a number of these bugs on a concrete driveway. Next to the driveway was a small bamboo grove which seemed to be the source of the bug. The maximum size was about 35 mm but most were about 20 mm long. None had any feelers/antennae. They tended to move towards a persons shoe if one went within a metre of them.
It was 11 am in mid April which is mid autumn (Fall) here. It was an overcast day, not raining, but with high humidity. Leura is 90 km (55 miles) from the Pacific ocean and is generally at 950 metres (3000 feet) above sea level. The vegetation is lush.
Any ideas?
Best Wishes
RobT
Signature: Robert T

Flightless Female Soldier Fly
Flightless Female Soldier Fly

Dear Robert,
This is a flightless female Soldier Fly,
Boreoides subulatus, a species with pronounced sexual dimorphism, with the males being much smaller and winged.  According to the Atlas of Living Australia:  “Female Wingless Soldier Flies are seen on walls and fences, laying masses of long white eggs. Larvae live in damp soil or rotting vegetation, especially in or near compost.”

Flightless Female Soldier Fly
Flightless Female Soldier Fly

Dear Daniel,
That is wonderful. I have lived here on the east coast of Australia for 30 years and prior to that in Southern Africa also for 30 years and was totally stumped.
Hope you and your family have a wonderful Christmas.
Regards
RobT

Letter 10 – Wingless Soldier Fly from Australia

 

Subject:  What’s this bug?
Geographic location of the bug:  Australia, Victoria, Dandenong
Date: 04/12/2021
Time: 05:02 AM EDT
Your letter to the bugman:  Hello bugman,
I’m curious about what this bug is. I have found a few in my shed. Any help will be greatly appreciated. A small donation haha.
Cheers
How you want your letter signed:  Nathan

Wingless Female Soldier Fly

Dear Nathan,
This is a wingless female Soldier Fly in the subfamily Chiromyzinae, and the first time we ever saw one of these, it had us puzzled for quite some time.  There are numerous images posted to iNaturalist.

Wingless Female Soldier Fly

Letter 11 – Yellow Soldier Flies

 

Subject:  long-bodied yellow-orange fly
Geographic location of the bug:  Buffalo NY, USA
Date: 06/27/2021
Time: 04:34 PM EDT
Your letter to the bugman:  Hi. I’ve never seen anything like these before. Dozens of them hovering over a patch of leaf litter with white fungus in a heavily shaded corner of our yard. They move around constantly and were not seen to land. Body length about 2.5cm.
How you want your letter signed:  JR

Yellow Soldier Fly

Dear JR,
These yellow flies reminded Daniel of some flies he saw in Ohio several times in June that he believed were Soldier Flies in the family Stratiomyidae, and a web search led to Red Worm Composting and an article entitled Yellow Soldier Flies Revisited where it states:  “As if this wasn’t cool enough, today when I walked by a bag of (compostable) used cat litter material – waiting to get added to my new litter vermicomposting system – I noticed a bunch of these large, yellow flies hovering around the bag.”  Eventually Dr. Stephen Marshal, at the University of Guelph identified them as probably
Ptecticus trivittatus.  We located a matching image on BugGuide.

Yellow Soldier Fly

Dear Daniel,
Thanks very much for the prompt response. Yes, that’s a match!
Much appreciated. Best wishes,
John Ringland

 

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

4 thoughts on “What Do Black Soldier Fly Larvae Eat?”

  1. Yessss! I just started a compost pile and saw these guys. It only took one search here to find out what they were. Thanks!

    Reply
  2. I’ from Australia and we have those wingless flies too but only at certain times of the year, ie, Autumn. I have tried to identify them too and came up with “wingless stratiomyidae”. I couldn’t find any detailed information about them, only that the larvae are flattened! Great, but from my own observations l think that the one in the photo is a female. I see them crawling up vertical structures, eg walls, plant stems etc. l think they are females looking for a crevice in which to deposit their eggs. Once l saw one with another similar looking creature which was considerably smaller and l wonder if this was the male.

    Reply

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