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 Attracting black soldier flies-the basics 
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Post Attracting black soldier flies-the basics
Attracting the initial black soldier fly (BSF) females to start up a BSF composter can be problematic if you don’t understand the basic principles involved. Of course the first step is to determine if your area is populated by BSF, but once you’re satisfied that they’re present it shouldn't be too difficult to attract them.

There will be other species in the beginning

You may have read that BSF larvae repel other fly species from laying eggs in waste dominated by BSF. This is true, but in the beginning of the start up process you will host other species like house and fruit flies. When your colony of BSF larvae reaches a certain density, you will see this amazing repellent effect. How long that takes depends on how quickly you can build up the BSF in your composter. With the right waste (BSF larva food) and a good local BSF population it might only be a few weeks. However long it takes, don't fret about it; it's only a minor inconvenience compared to what you have to look forward to once your composter has a layer of hungry BSF larvae an inch or two thick. :)

Realistic time frame

Often people are successful at inoculating their composters before they even know it. It’s important to understand that it can take 2 – 4 weeks from the time that eggs are laid until you can easily see the resulting larvae or “grubs”. Sometimes you can see clutches of eggs laid in the corners or crevices of the composter or bait container, however, often the females randomly scatter their tiny eggs on the inner and outer walls of the unit. That makes it almost impossible to see them without magnification. The newly hatched larvae are also tiny so after the bait (food scrap) has been out for several days they could be present without being obvious. For that reason it’s usually not wise to throw away any existing bait and start over; you may very well be discarding recently hatched larvae. Below is a photo of a black soldier fly larva (BSFL) on the sixth day after it’s egg was laid which makes it approximately two days old. You just can’t glance at a pile of rotting food and know if these little creatures are present or not.

Attachment:
BSF life cylce day 6 w.jpg
BSF life cylce day 6 w.jpg [ 82.3 KiB | Viewed 20507 times ]


Choosing the menu

Larvae of the black soldier fly (Hermetia Illucens) are designed to consume decomposing plant or animal material, or partially digested food (manure). If you set out fresh food scraps you won’t have a good chance of success until it begins to break down somewhat. You will always attract other fly species in the beginning, but once the BSF population expands to a high density they will dominate the waste causing other species to avoid it. Fruit, vegetables and grain can be used as bait but I don’t recommend adding meats until after you have established a dense colony.

You can attract BSF with a variety of foods but my favorite method uses grains. The reason is that they are easy to ferment and relatively stable, meaning they don’t become anaerobic (sewer-like odor) too easily. At least that’s how it appears to me. Anaerobic bacteria thrive in the absence of oxygen and BSFL do not do well in that type of environment. While you don’t want foul odors I do recommend using a strong sour odor to attract BSF females. I assume they follow a scent trail to the food source so I try to use a bait that I can smell from a few feet away. The difference between a sewer-like odor and a sour odor may not be clear to you immediately but we all understand the stink of a sewer and you don’t want that. I usually start with plain dried cracked corn from the feed store which is sold as chicken feed. It is covered in water and soaked for a few weeks before using it. Warm temperatures speed up fermentation so I usually leave the container in a sunny place. The odor resulting from the fermentation is very attractive to BSF because the sour grain is a good food source for them. I have a post about using fermented corn here: Attracting BSF with corn

Use the sun to improve your bait

BSF females are attracted to rotting food, so it's better if your bait is in the process of decomposition. If you have "fresh" waste like vegetable trimmings, or barely stale bread, you can speed up the rotting process by placing the waste in a black plastic bag, sealing it, and leaving it in a sunny place for a few days. One way to monitor the progress is to check for liquids that are released as vegetable rot. Once the waste is thoroughly rotten you can add it to your composter.

Keep the bait moist

One very good reason to keep the food scraps moist is that any larvae that might have hatched will need approximately 70% moisture to thrive. Another reason is that moist bait will give off a stronger scent trail than bait which has a dry crust on it. When I use fermented corn I keep it completely covered with water. If you’re keeping the bait in your composter with a filter pad I recommend temporarily installing a container to hold the bait so that you can more easily keep it moist. Below are photos of one approach I used in a BioPod Plus. The first photo is after two days and the second was taken a few weeks later. As you can see it would have been much more difficult to keep the scraps moist if they were sitting directly on the filter material. Shortly after the second photo was taken I added the waste and larvae directly to the composter. (What may look like large BSFL in the first photo is actually puffed rice.)

Image

Image

I didn’t use fermented corn in these photos because I didn’t have a batch ready. A few days after the the last photo was taken I placed a small container of fermented corn with its liquid inside the composter with the other waste. I already had larvae by then but the goal is to keep as many females coming to the composter as possible during the early stages. Once you have a dense colony established plenty of females will visit the unit to lay their eggs without any special effort on your part.

Keep the bait warm

The common wisdom is that a BSF composter must be kept fully shaded. This is true in most cases but there are notable exceptions. Just as you will produce a stronger scent trail by keeping the bait moist, you will also produce a stronger scent if the bait is warm. For that reason I kept the composter in the above photos in full sun during the period in April and May when I was initially attracting BSF. I would have chosen a shady place if this had been during the middle of the summer, but during the cooler days of spring a sunny spot worked better. The rule to remember about temperature, and sunny versus shady location, is simply this; try to keep the temperature inside your BSF unit roughly between 70ºF and 100ºF (21-38C). The generally accepted range that BSFL can survive is between 33ºF and 115ºF (1-46C). Our goal here is to keep them warm enough to stay active but cool enough that we don’t approach the fatal heat level. The reason overheating is such an issue in a densely populated composter is that the larvae generate a lot of heat as they metabolize waste. In a unit that has no larvae yet or is thinly populated overheating is only an issue when daily (ambient) temperatures are very high.

Divide and conquer

It makes sense that your odds of successfully attracting BSF females will be higher if you set out bait in multiple locations on the same or different properties. Of course you can choose to attract BSF directly to your composter, but using a separate container for bait makes it easier to experiment with different locations if you don’t want to move your composter around. While you can use almost any container for the bait you will probably have better results if you use something that supports the goals of keeping the bait moist and warm. It’s also a good idea to prevent excessive rainfall from entering and flooding or diluting the food scraps. Your attractor unit can be as simple as a bucket with a lid and few holes cut into the sides. I’m currently testing a design that uses a common plastic coffee container and I will post photos of it soon.

Another alternative; don’t wait for BSF to find you

Setting out baits to attract BSF females can be very effective, but I also recommend hunting for eggs and larvae. I regularly advise people that a great way to find BSFL is to start a traditional compost pile which includes kitchen scraps or find someone who will let you search in theirs. The kitchen scraps are important because BSFL are not designed to consume high cellulose items like grass, leaves and paper. If you can collect some larvae from a compost pile you probably won’t have enough to fully populate your composter, but the larvae are a powerful attractant to egg laden females. Add the collected larvae to your BSF unit along with some of the compost they were found in. As mentioned above; keep the material moist and warm and the subtle scent of the larvae plus the odor of the food scraps will work very well.

Another option is to hunt for BSF eggs which are then added to your composter. You can often find eggs that have been laid on household garbage cans. To be honest this is the most frequent method I use for starting new units in the spring. Consider that a typical garbage can has all of the elements to satisfy the basic requirements for attracting BSF; they contain decomposing food, and they tend to be moist and warm inside. When I want to attract BSF I leave one of our garbage cans full for an extended period so that it starts to give off a noticeable odor. In my experience it works like a BSF magnet. Since we use black can liners the light colored eggs show up very clearly. I take an old knife and gently scrape the clutches of eggs into a small lid or shallow container and place it in the composter on top of the food scraps. When the larvae hatch they will crawl into the waste and begin eating.

Image

Those are the basic concepts based on my experience. BSFL eagerly consume anything that humans eat and more, so you don’t necessarily need to limit yourself to what I’ve mentioned here. I assume what I’ve written here can be improved on, but it will get you started. Check back soon if you’re interested in seeing my coffee can BSF attractor. :)

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Wed May 18, 2011 3:35 pm
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Post Re: Attracting black soldier flies-the basics
Great article Jerry, Just what I needed as I get ready to start. My conversion unit will get a last couple of coats of paint and varnish tomorrow and attach the effluent catcher on the bottom then I will load up and start hunting for eggs. The last picture in this article is just small larvae right? or is that what the eggs look like. I can't remember if I have actually seen pics of eggs. Aren't they tan creamy color and a solid paste looking consistency?

Thanks Brandon.


Sat May 28, 2011 2:59 am
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Post Re: Attracting black soldier flies-the basics
Brandon, those are eggs on the can liner.

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Sat May 28, 2011 10:57 am
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Post Re: Attracting black soldier flies-the basics
Here are snippets from a few posts elsewhere on the forum that have info on what materials have been used as attractants:

Jerry (link):"I've seen a few reports that bokashi compost and tea are excellent attractants for BSF so that's my main purpose in researching it."

Quote:
Now What Do I Do?

Now that you have the output of your Bokashi the question is what can you do with it and there are a number of options –

Add it to your existing outdoor composter if you have one
Add it to a worm farm if you have one of those
Dig it in directly into one of your veggies patches as is.
Use it to attract black soldier flies. This is the stuff of a whole ‘nother article but briefly you can use you bokashi output in a commercial or homemade black soldier fly larvae farming set up. This set up induces the black soldier fly to lay eggs in or around vegetable waste then captures the larvae (maggots) as they go looking for soil to pupate in. The maggots can then be fed to chooks or fish in an aquaculture system. I have found that the bokashi material attracts black soldier fly like nothing else!

From: Under The Choko Tree - Making your Own Bokashi Bucket



Athelas (link):"A note on the Bokashi:
Leaving it out in the open does not seem to attract BSF, putting it through a blender and adding about 20% water seems to bring them around.
I use de-chlorinated water, i.e. Water that's been allowed to stand for a few days, to get rid of the treatment plant additives.
"





PeteB (link):"I've found that a bucket of pumpkin is a great attractor, especially after a few days when it starts to get bubbly. As an added benefit, it actually smells quite pleasant. :) "

Image

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Sat Feb 23, 2013 10:40 am
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Post Re: Attracting black soldier flies-the basics
PeteB wrote:
I know nothing about bokashi, except that fermentation is part of the process, and we know BSF like fermentation (soaked corn, brewery waste, etc.)
I've found that a bucket of pumpkin is a great attractor, especially after a few days when it starts to get bubbly. As an added benefit, it actually smells quite pleasant. :)

Image


Thanks Peter, I'm going to try that.

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Sat Feb 23, 2013 11:30 am
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Post Re: Attracting black soldier flies-the basics
Jerry recently said in his flooded-coir thread that "It has a fairly strong but pleasant sour odor reminiscent of beer."

Above, there are bits advising fermented grain and bubbly pumpkin as attractants.

So, has anyone tried stale beer? The "girls" might think there's a party going on and head straight for it! It would also cut down the fermentation time needed for the grain. Or soak the grain IN the beer?

Sue


Tue May 28, 2013 3:34 pm
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Post Re: Attracting black soldier flies-the basics
Even though beer is a fermented product I doubt there is much active fermentation happening in a freshly opened bottle. The smell would probably be at least somewhat attractive to BSF but I think you could create fermentation quickly enough without destroying perfectly good beer and making Brian cry. :cry:

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Tue May 28, 2013 4:43 pm
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Post Re: Attracting black soldier flies-the basics
Jerry wrote:
... I think you could create fermentation quickly enough without destroying perfectly good beer and making Brian cry. :cry:


You know me too well, Jerry! ;)

As a home brewer with some experience in disposing of spent brewing grain, I can personally attest to their efficacy as a BSF attractant. But I want to correct a possible misunderstanding. The spent grain has NOT been fermented! There is NO alcohol in the spent grain!

In the brewing process, the malted barley is mashed by infusion with hot water at various temperatures designed to enzymatically convert the starch in the grain to maltose based sugars. The maltose "wort" is rinsed from the grain with added hot water in a process called "sparging" and drained off to be condensed into a more concentrated sugar content through boiling (while killing off bacteria and undesirable wild yeasts in the boiling process). This boiled wort is then rapidly cooled and brewers yeast is added to start the fermentation process for what will soon become beer.

The spent grains are disposed of while still moist with a very weak solution of maltose and water. This moistened grain is automatically inoculated with lactobacillus bacteria which reside on the surface of the grain husks. No yeast is present in the grain, but the bacteria EXPLODE in population from feasting on the residual sugars, starch and moisture. It is my belief that the lactobacillus bacteria serve as the chief attractant in spent grains. I also think this is why cracked corn steeped in water with a bit of added sugar works so well as an attractant! 8-)


Tue May 28, 2013 7:22 pm
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Post Re: Attracting black soldier flies-the basics
Jerry wrote:
Even though beer is a fermented product I doubt there is much active fermentation happening in a freshly opened bottle.


Correct again, Jerry!

The amount of alcohol in beer is determined primarily by the amount of fermentable sugar in the wort. When the fermentation is complete and the beer has carbonated in the fermentation vessels, the beer is filtered to remove the spent yeast, then pasteurized to kill off any unfiltered yeast before bottling or kegging.

A very few select "craft brewed" beers are allowed to complete their fermentation in the bottle to "bottle carbonate" the bottles. These bottles go unpasteurized. There is a yeast residue in the bottles of these craft brewed beers.

But once again, it is the lactobacillus bacteria in the spent grains, not the alcohol or the brewers yeast that attracts the BSF. I would surmise that curdled milk, cottage cheese, or yogurt would be good attractants for this very reason too! :ugeek:


Tue May 28, 2013 7:41 pm
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Post Re: Attracting black soldier flies-the basics
I saw all of the processes Tarvus is describing as the brew master at Orlando Brewing was putting the byproducts into my buckets. :D

I also learned that their beers are unpasteurized.

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Tue May 28, 2013 7:46 pm
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Post Re: Attracting black soldier flies-the basics
Jerry wrote:
I saw all of the processes Tarvus is describing as the brew master at Orlando Brewing was putting the byproducts into my buckets. :D

I also learned that their beers are unpasteurized.


Damn! I will have to try their beers! :)

I will be interested in hearing your results with the brewers yeast! The fermentation process in not 100% perfect and there are normally some unfermented dextrins that remain in the beer (probably the reason it is so fattening!) These unfermented dextrins will be present in the yeast slurry you were given. The yeast will die off and the yeast cadavers and sugar water may prove to be a fertile substrate for lactobacillus! Please keep us updated! 8-)


Tue May 28, 2013 7:57 pm
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Post Re: Attracting black soldier flies-the basics
Do the adult female flies seem to have any preference for the light or darkness of the egg-laying area? Or dislike?

Sue


Sun Jun 02, 2013 7:31 pm
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Post Re: Attracting black soldier flies-the basics
BelgianPup wrote:
Do the adult female flies seem to have any preference for the light or darkness of the egg-laying area? Or dislike?

Sue


At least 80% of the eggs I collect are from the bottom side of the eggs traps. This could be light related or possibly gravity related (perhaps they just like to lay in the "heiny up" orientation?


Sun Jun 02, 2013 8:32 pm
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Post Re: Attracting black soldier flies-the basics
Hi y'all,

I started my first BSF bin this year with the contents of a full Bokashi bin that had been processing for 2 - 3 weeks. The females came right to it. I make my own bokashi bran with wheat bran purchased in the bulk section at Whole Foods, to which I add some molasses, worm castings, Vermiplex (stabilized worm tea) and on the next batch I'll put in some EM (efficient microbes) from SCD in Kansas City.

It's a lot cheaper than buying bags of Bokashi bran pre-made. I use it between each layer of food scraps that go into the Bokashi bin and tend to go a bit heavier on each application than I would if I were buying it from a supplier.

I'm thinking that the wide variety of aerobic micro-organisms are likely to be very beneficial to the health of BSFL, as well as each own doing their breakdown thing. Might add some BioZome as well to speed things up and inoculate each bin with the anti-aneroebic factor.

My buddy Gordon - SustainacycleKyle.com - says Bokashi is not a wise thing to feed worms, unless they have a way of getting away from it in a large compost pile. The pH is wrong.

I have a regular fenced compost pile near my bins and it is a great attractant and loaded with grubs lately. It seems like there's plenty of laying of eggs going on, so it's not a big deal that they're not all going to my bins to lay.

One thing I've been thinking about this year is the downside of using corn due to the prevalence of genetic modification. I used fermented corn to great success a few years ago, but now I'm reading a lot about its longer term effects on animals and potentially humans. I suppose non-GMO corn is available but I haven't looked into it yet.


Fri Jun 07, 2013 9:08 am
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Post Re: Attracting black soldier flies-the basics
Another observation. I recently acquired a vortex brewer to make worm-compost tea. I run it for 36 hours with molasses and worm castings, then use it as a foliar spray. The first batch I ran a few weeks ago attracted BSF. They were buzzing all around the top.

I'll try an experiment on the next batch, using some of it in a new bin without any food scraps in it, just some coir. I'll place it somewhere away from the existing bins. Not really thinking they'll lay eggs there, if there's no food, but just to see how powerful the scent is in attracting them to it.

It would be a cheap thing for someone to use a 5-gallon bucket and an aquarium aerator and produce some tea quickly for attraction purposes. Maybe use it to water the first batch of scraps that are put out. Maybe use it for cooling water also. The aerobic microbial population after brewing is huge and that seems like a good thing for active bins.

Thanks everyone for some fascinating reading while catching up over the last couple of day.


Sat Jun 08, 2013 11:12 pm
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Post Re: Attracting black soldier flies-the basics
I'm not too surprised about the worm tea since BSF are very attracted to worm castings. The tea and molasses sounds like a potent attractant.

I've been experimenting with liquid brewery byproducts and one idea is to flood a coir base with it to see if it can support a colony. I've seen BSF living in a flooded environment, but I think it's probably preferable to have some bulking material.

I've been using liquids from flushing my BSF units to wet other units thinking it would help attract females. Also, since I'm doing a lot of flushing I'm getting a lot of BSF tea. I've never worked with worm or compost tea before so I've started a thread about if anyone wants to offer advice: http://blacksoldierflyblog.com/forum/viewtopic.php?f=38&t=474

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Sun Jun 09, 2013 12:58 pm
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Post Re: Attracting black soldier flies-the basics
Jerry wrote:
I'm not too surprised about the worm tea since BSF are very attracted to worm castings. The tea and molasses sounds like a potent attractant.
Interestingly I had someone email me suggesting that spraying diluted molasses on coffee grounds or in a bin will promote mating/ovipositing.

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Tue Sep 10, 2013 12:57 pm
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Post Re: Attracting black soldier flies-the basics
BorealWormer wrote:
Interestingly I had someone email me suggesting that spraying diluted molasses on coffee grounds or in a bin will promote mating/ovipositing.


The "Manna Pro" horse feed I have used is grain based with molasses added and it certainly does well in attracting ovipositing BSF.


Tue Sep 10, 2013 1:04 pm
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Post Re: Attracting black soldier flies-the basics
Though these critters showed up in my compost bins, I thought they were invaders. My only awareness of good composters was of worms. I actually abandoned composting for a few years because I didn't want to see the BSFL. Yeah, ignorance is sad but a first step towards learning, eh?

It it a fairly recent thing that I promptly take the tub of compost out after a day or two. I have long been kind of like a mad scientist though, putting kitchen scraps in a clear jar and just seeing what happens and being able to experience different rot smells inside just by lifting the lid! Terrible, I know. I probably should be terribly embarrassed but I'm past all that. Besides, after the times when the lid was not put on tight and fruit flies came, I took delight in being able to give our aquarium fish fresh food in the form of fruit fly larvae. Fish have more personality than I had previously recognized.

So it was this laissez faire kind of composting that led to me feeling like a queen of biodiversity for our little corner of suburban condo land. We took our yard from sterile lawn to host for mushrooms, different lizards, BSF, and who knows what else is coming.

Incidentally, it was while researching bokashi that I found this blog and forum and found my love for BSFL. Thanks for this Forum!


Fri Nov 15, 2013 3:33 pm
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Post Re: Attracting black soldier flies-the basics
Jerry,

Have you ever used coffee grounds or livestock manure to attract BSF?

Byron


Fri Jul 18, 2014 2:03 pm
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