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Black Soldier Fly and Vermicomposting

I have a small colony of BSF active in my worm bins. Have found they are difficult to displace and the end product in the bin is not the same as it used to be as it gets more moist at the bottom of the bin.

 

Have been reading Dr Paul Olivers findings about the potential benifits of having these characters in your worm bins.

http://http://www.redwormcomposting.com/bsfl/black-soldier-fly-larv...

http://http://blacksoldierflyblog.com/

 

I have found that overall the BSF are dormant during the winter months here in Japan but were thriving right through the hottest 4 months of July, August and September here in Japan, We had had the hottest summer on record in 2010

 

For the winter months, My worm bin has a water heater keeping a steady temperature through the winter in part of the bin at 20.C.That is where some of the BSF tended to concentrate this winter. The worms were very active in this period.

This summer weather was not great fun for the worms but the BSF were in their prime.

 

BSF do make the plastic Can O worms bin I have get very moist and this could have caused problems. For a while I found worms concentrating at the top and bottom of the bin. Adding plenty of cardboard bedding and taking out some of the BSF seemed to calm the worms down. The plus side of their presence is that I was able to process alot more food waste in the bin this year at a quicker rate.

 

What are folks opinions on these fellow food munchers?

 

Views: 2715

Comment by Philip Vanderhoofven on February 22, 2011 at 1:18am
I dont mind the Black Soldier fly in my bins. Of my three bins (COW, WF360, & Flow Through) that I have they are only now in the flow through. They eat a bunch of garbage. The draw back is that they rob the nutrients from the soil and convert the compost into maggot flesh instead of rich soil like the worms would do. If I had a few chickens that would even be better because I would feed these large maggots to the chickens.
Comment by Don Dillon on February 22, 2011 at 6:20am

Testify, Steamy, Testify!!!   I hate the beggers myself.  If I could keep them separated from my worm bin, I wouldn't mind having a bsfl bin going, but I don't think that is going to happen.  

 

I wonder, would it be possible to close off the bin (screening for air flow) and leave a bsfl ramp (like in the custom bsfl bins) so they can leave, but not allow adult bsfl to come in and lay new eggs? Would they empty themselves out of the bin within a season?

 

And are they very hardy?  I had about 60 gallons of worm bedding w/bsfl larvea that was left out over a very cold virginia winter.  the worms survived (don't know percentage, but hoping for a large egg hatching), but is there any chance that the maggots and eggs froze to death?

Comment by Robert Olivier on February 22, 2011 at 5:28pm

 fall start introducing red worms and bring the unit indoors. this disrupts the grub native reproductive cycle and I harvest less and less grubs, while the earth worms have time to reproduce. I eventually seal of the drainage and the harvest ramp and turn it into a worm bin. As the grubs had been churning the waste all year, aeration is not that big of a concern. But I add less food waste to this system in winter. Come spring I have casting ready for the garden... I can't collect the casting inside the BioPod as easily as with a good worm bin, so I just empty it out and separate the worms from the castings. then I restart the biopod for the grubs as their natural reproductive cycle starts up again.

Comment by Robert Olivier on February 22, 2011 at 5:28pm

Here's the way I see it.

 

Soldier Grubs are GREAT at breaking down food waste and converting it into living protein. They are not real good soil builders, their digestive track is short. They can eat things in a very short amount of time like meats and diary that otherwise would compromise a worm bin. They shred the waste first and release moisture. this requires adequate drainage while the earth works at a slower pace preventing the quick release of cellular moisture. Soldier Grubs are nich dominant and will raise to temperature in your worm bin to a level not comfortable for the worms. 

 

Worms are Great at building soil. They have a long digestive track, their castings are valuable and they are able to break down some of the harder to digest plant matter that has little nutrient content for the soldier grubs. they do not tolerate high temperatures as the grubs and take a longer time to reproduce. Worms do not reproduce as quickly as grubs do and are therefore more valuable as a recycling organism. Harvesting worms to feed to chicken only makes sense when you have a lot of worms relative to chickens.

 

My conclusion: do like nature does... first the soldier grub for nutrient conversion, then the earth worm for soil building. When something dies in the forest, maggots are the first line of decomposition... Earth worms finish this process and create fertile soil.

 

I have tried to create contraptions that house BOTH organisms at once. I never got it to really work. I can't get the food waste to travel one way while preventing the grubs from eating the worms dinner also.

 

I prefer to separate the 2 "colonies" by either space or time.

- Space: have 2 physical different bins one set up for grubs with drainage and harvesting mechanism, another for worms that allow me to harvest castings

- time: operate a BioPod from spring to fall outdoors with grubs and adequate drainage. then come

Comment by Robert Olivier on February 22, 2011 at 6:18pm
yes, they do migrate out when you bring them indoors... that's why I use a bin with a harvesting mechanism for the grubs. It's not hard to make a grubcomposter into a wormbin... but using a wormbin to harvest grubs will not work. Especially if there is some moisture to the bin, they will crawl out of anything. No matter how tight a lid might be. Thanks for pointing that out.
Comment by Robert Olivier on February 22, 2011 at 6:46pm

To answer your first comment to this post on How to get rid of them. I would like to point out that it's very hard to do when outdoor temperatures are favorable to flying insects (adult bsf, bees, etc).

Sanitizing your worm bin makes no difference, as the adult black soldier fly females come from your yard and lay eggs in your bin. even the smallest crack is enough for them to lay 2000 eggs. there is no way to sift out those small eggs and resume your worm bin. As long as you have foodwaste in a bin outdoors they will come lay eggs during the warmer months of the year. They are present on all continents. You're fighting an uphill battle. When it comes to fresh food waste, they are dominant.

The only solution I see, would be to keep your wormbin indoors all year long after you cleaned it out. That way you avoid the adult soldier grubs finding your bin. Without a strong odor to guide them to your worm bin, they will avoid coming near your home or anything with artificial lights. However, if you put them in a garage and leave the door open they will not resist the attractive smell of a food waste. Artificial lights alone are no guarantee they will stay away.

 

A few years ago we tried to kill them. You can put them in the freezer and some of them will crawl again the moment you warm them back up. They do not stop moving if you put them in pure rubbing alcohol. You can slowly starve them, but it takes weeks.

Comment by Robert Olivier on February 22, 2011 at 8:21pm
if you can't beat em join em
Comment by Heather Rinaldi on February 22, 2011 at 8:29pm

Hey Robert, glad to see you here.

Worms and BSF can work in harmony...in an outdoor, open trench system.  That way, the worms can move from the hotter zones when they need to (always leave a location in the bin that doesn't have fresh food), the heat dissipates from the bin, worms can go eat BSF poo when they want and life is good.  Use a 1/4 to 1/8 compost sifter to sift the BSF out and feed to the chickens/fish in the pond/etc..  Add another nitrogen source to a small zone in the large outdoor bin, and nature repeats itself.

 

Work with Nature, and Nature will work for you. 

Comment by Robert Olivier on February 22, 2011 at 9:15pm

 fly, but it also kills all beneficial insects. Now, with the grubs and worms gone the stables starts to stink and now we need somebody to go clean it out every 14 days. This then creates a lagoon that is an agglomeration of anearobic stinky compounds mixed toxic man made compounds... it this point neither nature nor man knows what to do with this mess anymore.

 

So which is worse... a few maggots in a well managed system or a labor intensive cesspool? I say the cess pool is worse, and if you have the right type of grub in there you can actually discover its benefits.

Comment by Robert Olivier on February 22, 2011 at 9:15pm

Hey heather... likewise great running into you and also a great point. I guess everything depends on your climate and the amount of food your process as it relates to your bin size.

 

Large bins can easily allow for both species to live together, just as they would in a natural setting. Its the smaller bins with the large amounts of undigested food that get easily overrun with soldier grubs and then they will outdue the worms. Not because the grubs are mean, but because their fast metabolic rate in a confined space makes it twice as hot for the worms to co-exist within the same small space. For both species to co-exist they need their own space to regulate their optimal conditions (temperature and heat mostly, some ph concerns with the grubs might also play a roll for the worms) Large systems will easily buffer this, small systems have a harder time.

 

However, steamyb seems to want a grub proof worm bin. And I honestly don't know what to tell him. My only advise at that point is to isolate your wormbin and make sure no female soldier grubs can fly near it to deposit some eggs. Try finding a compost pile in Texas with food waste that doesn't contain grubs in summer time. You can't.

 

People have had the same aversion to maggots and in most cases that biological instinct is there for a reason - "Please don't eat". That DOESN'T mean that they are bad and you should sterilize it. Horse stables used to be so much cleaner when they had living floors, a few inches thick and all kinds of insects managed it like an autonomous biological micro-cosmos. People could leave the compost in there for years and the horses never had to live within a cloud of ammonia and you rarely found a house fly. Hence the reason the Black Soldier Fly used to be called the Privy Fly and there were tons of earth worms living in those stables with them.

 

Today, we put larva side and insecticide with the horse feed... yes it kills the house

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