Black Soldier Fly (or Not?)



Thanks for the reference – excellent website –  but I think you might have missed something – they usually start off light coloured and get darker as they approach the change into pupae. You say they seem to have expired – I wonder if they are not just pupating and will turn into flies soon.



From: Tony Fister
Sent: 17 August 2009 12:47 AM
To: steve
Subject: Re: Seeking advice



Absolutely fine to post on your blog.

I had seen the page you referenced.   I’m just having difficulty identifying them.  🙂 Based on this link…

… it looks like it may not be the BSF. It appears that the small BSF

larvae is very dark in color.


In any event, the larvae have been climbed up the sides of the walls of

the bin and have turned from a bright white color to a light brown color

and it appears that they have pretty much expired.


I guess I’ll find out over the course of the next few days or weeks if

whatever is in there has affected the habitat of the red-wigglers.






Steve wrote:

> Hi Robert

My guess is that you most likely have Black Soldier Fly – DON’T PANIC  – these are actually good guys – see attached extract below from our  Website – “Handling Vermiculture Pests and Other Problems” –

However it could also be housefly larvae or blow flies – not so nice –  but flyscreen cloth and a few fly tapes will sort this out – no meat or fat in bins – stick to vegetable matter.

I’d like to post this on our blog –  –  ok with you?

Good luck.

 *Black Soldier Fly*

 Latin Name: /Hermetia illucens/. It is a moot point as to whether this

> fly should actually be called a pest. It is a tropical fly, originally

> from the Americas, that has now spread around the world. The larvae of

> the fly are a type of small maggots, that feed exclusively on

> putrescent material. They are often found in worm farm bins, but

> although unsightly are not a real threat to the worms, as they do not

> attack them and may in fact complement the compost worm’s activities,

> rather than compete with them for food. Like the vermiculture worms

> their faeces make excellent compost and the maggots are also useful 

> as a high protein fish or poultry feed and may be used either live or

> dried, as a processed meal. They may also be used by the less

> squeamish for fish bait. They can best be kept out of the worm farm

> bins, by not using meat and fatty waste and by keeping the moisture on

> the dry side, and making sure that there is a good cover of  bedding

> material over the feeding area.

> These remarkable creatures, unlike the common housefly, do not spread

> bacteria or disease – in fact the larvae ingest potentially pathogenic

> material and disease-causing organisms and thus render them harmless.

> Moreover black soldier flies exude an odour, which positively

> discourages houseflies and certain other flying pests. When the larvae

> reach maturity they  leave the feeding area  to pupate, preferably  in

> a shady bush or tree. After turning into an adult fly, the female

> lives a further 5-8 days and produces almost 1000 eggs. The adult fly

> is nocturnal and characterised by very fast and rather clumsy flight.

> It has no mouth and cannot bite or sting.> There is a growing interest in using Black Soldier Fly for commercial processing of sewage and agricultural waste. Some hobbyists have been > experimenting with the Black Soldier Fly, as an alternative to vermiculture, for for private composting/ waste disposal. For the same size of container it is said that a well stocked colony of Black Soldier Fly would be able to process waste material very much faster

> than a comparable sized worm farm.

> —–Original Message—–

> From: Tony Fister 

> Sent: 16 August 2009 03:46 PM

> To:

> Subject: Seeking advice

I have a newly established bin (2 weeks old) and it has been running fine – no smells, no flies hovering over the container, the worms were doing their jobs. Three days ago I fed the worms, careful to add the food to the bottom of one side of the pile. I added some additional  shredded newspaper bedding on top of that. Last night I checked the bin to see if they had jumped on the new food (I’m trying be careful not to over feed) and I noticed the presence of a  bunch of white larvae about 1/8″ to 1/4″ in length. They were the only thing consuming the new food and the red wigglers had remained buried  deep in the older section of the pile. What I was hoping to learn is this.


> A.  What the larvae might be (probably any one of a hundred things I’m sure)

> B.  What threat, if any does the larvae pose to the red wigglers? Will  they harm the wigglers or is they just competition for the food?

> C.  Is there anything I need to do to get rid of the infestation or will  it resolve itself?

> D.  How to prevent future infestation.  It sounds like a piece of  plastic over the bedding might help

 Note, my worm bin is for my own personal home project. This is not a medium or large scale worm “farm”. I have a bin consisting of 2  Rubbermaid containers, one (with holes for ventilation and drainage inside another (no holes).


 Many thanks,


> Robert


1 Comment

  1. steve

    Hey Steve.
    I figured out what I was describing to you. They are not BSF larvae.
    What I am seeing are only 1-to-2 mm in length so they don’t match the
    description. However, they do match the description of fruit fly eggs.

    Now, that said… I took a look at the bottom of the bin today and I saw
    for the first time many larvae that did match the description of the BSF
    larvae. It looks like they are helping the worms out and I have a bit of
    a fruit fly issue that I may have to deal with.

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