From a post on the CleanTick blog (link)

I would love to know how they extracted that oil. From what I've read the oil is yellow. I've been trying to research the different ways people have extracted BSFL oil. Any ideas?

There have been various projects but I don't know of any that got further than bench scale tests. Here are a couple of old links:

http://www.biodieselmagazine.com/articles/3349/ecosystem-uses-fly-larva-to-make-magfuel/

http://www.cals.ncsu.edu/waste_mgt/smithfield_projects/phase2report05/cd,web%20files/A2.pdf

"There is a potential to recover energy from the processing of swine manure with black soldier fly. Since the prepupae have a high fat or oil content (Table 2), this oil might be used as an energy source. If swine manure were converted to black soldier fly prepupae at 16% of the manure dry matter, as shown above, and they contained 30% or more oil, separation of the oil followed by conversion to biodiesel would yield as much energy as methane fermentation of that same manure (Tom Richard, personal communication)."

This summer, I am going to attempt to make BSFL oil into biodiesel, myself. All of the Chinese researchers that I have come across are drying the larvae, grinding them, soaking them in petroleum ether, and then evaporating it off to get the oil. I tried drying them, and then pressing out the oil, with no luck. I also tried boiling them and then suctioning off the oil layer which worked pretty well. One of my collaborators (PeteB) had even better success with this method. I hope he will post his pictures and elaborate on his methods.

Thanks for sharing the articles. I had come across them in my studies. I also read one from Fuel by Li, et.al. called "From organic waste to biodiesel: Black soldier fly, Hermetia illucens, makes it feasible" in which they compare the amount of oil extracted when BSFL are fed a diet of pig vs. cattle vs. chicken manure and the chicken manure produced the highest oil-yielding BSFL.

Good stuff Robin Looking forward to hearing more about your experiments. If you and PeteB have a lot of material to post I'll split your posts above off into a separate thread.

Here is a picture of some oil I managed to extract from BSFL by boiling them. It took ~ 100 to get this much, but my methods are pretty crude.

Robin, have you tried hexane as solvent? Its non polar, so you can use ground wet larvae as feed stock.
Agitation/stirring should be enough to extract at least a large portion of the oil (you don't need any expensive soxhlet apparatus). You still need some kind of distilling apparatus to separate the oil from the hexane though, but I'm guessing that the oil yield would be closer to what the literature are quoting.

Here is what I did: I washed the BSFL, then dried them for two days in a 60 degree Celsius oven. I read about others using a micromill to grind them up, but I don't have access to one, so I ground them using a mortar and pestle. I transferred the ground BSFL to a coffee filter and poured hexane over them into a shallow bowl. I let the filter "bag" soak in the hexane for a few minutes and then I pulled it up to let the oil drip through. The hexane evaporates within a short time (couple of hours) without any help--no rotary evaporator necessary. There is a lot of sediment in the oil, so I used a centrifuge (thanks for the idea Peter!) to separate out the oil.

The problem I see with most of these methods being discussed is one of simple economics. Hexane, or petroleum ether, or even the fuel or electricity cost involved in boiling or distilling are going to cost more than the value of the resulting oil produced to be used for biodiesel. Besides which, if one is seeking a "green" biodiesel product so as to avoid using petroleum based diesel fuel, it makes little sense to used petroleum based hexane or ether in the production process or to burn coal or gas generated electricity to produce it.

If the hexane or ether are recoverable/recyclable and the potential BTUs from the biodiesel sufficiently exceed the BTU's required to produce it, then it might make sense.

I seem to recall reading something about a mechanical process to express the liquid from live larvae then centrifuging to separate the oil from the water, but I don't recall where I saw it. Such a process would also leave the resulting dry matter available as a fish or soy meal alternative - unpolluted with petrochemical contaminants and at a much lower energy cost.

Good points! Today here in Abilene it is 108 degrees, so I really could bake them outside, thus reducing the cost of using the oven (however, the ovens stay on 24/7 in the lab using the energy any way). If I used the rotary evaporator, I could recover the hexane and recycle it, but there is energy involved with that, too. Did you know that nut oil is sometimes extracted using hexane? Hmmm...we've probably consumed some of that chemically-laden stuff ourselves. I don't know if it would be economically feasible in the long run, right now I'm just seeing if it can be done. And, I'm taking the easy way, because I don't have a lot of time to get this project wrapped up. Biodiesel burns cleaner than diesel and it can just be used as a fuel-additive which will improve the emissions from regular diesel. Black soldier fly larvae are composed of several different types of fatty acids (eleven, according to one article), not all of them conducive to conversion into biodiesel. Even if it never works out for BSFL oil to be used in the production of biodiesel, maybe I will learn something useful while trying to convert it into biodiesel. If it makes my fellow BSF lovers feel better, I've spent most of the summer working with castor oil. I'm just now getting a big enough crop of BSFL to work with. It has been a hot and dirty job! What I'm wondering is why do they always smell like blueberries even when they've been eating everything except blueberries?!

<a href="http://s1173.photobucket.com/albums/r590/robinhart79/?action=view&amp;current=IMG_09201.jpg" target="_blank"><img src="http://i1173.photobucket.com/albums/r590/robinhart79/IMG_09201.jpg" border="0" alt="grinding BSFL"></a>

<a href="http://s1173.photobucket.com/albums/r590/robinhart79/?action=view&amp;current=IMG_10701.jpg" target="_blank"><img src="http://i1173.photobucket.com/albums/r590/robinhart79/IMG_10701.jpg" border="0" alt="Ground BSFL prior to hexane application, Notice the grease on the filter."></a>

<a href="http://s1173.photobucket.com/albums/r590/robinhart79/?action=view&amp;current=IMG_0971.jpg" target="_blank"><img src="http://i1173.photobucket.com/albums/r590/robinhart79/IMG_0971.jpg" border="0" alt="Photobucket"></a>