Black Soldier Fly Forum

Are BSF an invasive species?
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Author:  Jerry [ Wed Aug 14, 2013 7:32 pm ]
Post subject:  Are BSF an invasive species?

Austin from Olympia asked this question, and it's one that has come up before on my blog. It's been a while since I addressed it, so here goes. Of course much of this is speculation on my part and I welcome differing perspectives.

I have read that black soldier flies originated in the southeast, and I assume that they have naturally expanded their range over time. I believe that because their current range seems to fit a pattern where they would have migrated into regions that support their environmental needs. Perhaps the BSF on the northern fringe of their range slowly adapted to progressively cooler climates, and also to drier climates on the western edge, allowing their range to expand.

To directly answer the question, no, in my opinion BSF can not be described as an invasive species. (Non-native species disrupting and replacing native species) BSF are native to the US, and I don't believe they displace native species. Instead, I believe that their population has grown with the human population, since BSF are well suited to consume our plentiful waste. If I'm correct about that, then BSF haven't displaced other species. If they do displace another species it would be houseflies and other types of flies which have also benefited from increased human activity.

It is thought that BSF expanded around the world by hitchhiking on ships, starting with Columbus, but, even on a continent where BSF are non-native, I don't think they fit the definition of an invasive species. That's for the same reasons I gave above, about how their expansion and success is linked to the growth of human generated waste. More about that below.

Black soldier fly larvae are different from many fly species in that they spend much more time in the larval stage, and do all of their eating in that stage. (BSF adults don't eat) Therefore, BSF require large amounts of rotting food or manure to thrive. In the absence of human activity (copious food waste, livestock manure) I imagine that an otherwise healthy population of BSF would probably die out.

I've read that house fly larvae can fully develop in as little as 8 hours under optimal conditions. Compare that with BSF larvae which can mature in two weeks at best. That represents about forty times longer spent eating. This may mean that in an environment with little manure or food waste available (absence of human activity), house flies could survive, but BSF would not. All of that is point out that BSF are not likely to be invasive, even as non-natives, because their population has grown as a result of the increasing availability of food provided by humans.

Maybe we need a classification that is related to "invasive species", but instead would describe non-native species that are beneficial, or at least neutral, to the environment. :)

Author:  Austin from Olympia [ Wed Aug 14, 2013 8:35 pm ]
Post subject:  Re: Are BSF an invasive species?

Thanks for the in-depth reply, Jerry.

Perhaps there is a biological synergy between human activity (and our waste) and the Black Soldier Fly. Additionally, their larvae-centric lives, as you pointed out, might also add to a quality of being un-invasive: if they can be relatively contained, and when they do develop into something with wings, they seem to go right for reproduction, how are they getting in the way of anything?

I don't mean to advocate for a native only operation, but if I am going to cultivate these, I want to be sure that I won't be messing up my neighbors, or my neighbors' neighbor, operation. Has there ever been a BSFL disaster? I can't find one. Everything seems to be gold about these things. It's a silver bullet I've been looking for..

Obviously using "invasive" or "native" is a somewhat relative term (what is the reference point, anyway? 50 years ago, 150 years ago, 1500 years ago?).

Where I draw the line is when a species comes in and not only replaces another, but causes a whole disruption in the system.

Author:  Jerry [ Wed Aug 14, 2013 8:55 pm ]
Post subject:  Re: Are BSF an invasive species?

My pleasure Austin.

I my six years of reading about black soldier flies I haven't found any claims that they have negatively impacted an ecosystem.

Author:  BorealWormer [ Wed Aug 14, 2013 9:03 pm ]
Post subject:  Re: Are BSF an invasive species?

Austin from Olympia wrote:
... Has there ever been a BSFL disaster? I can't find one. Everything seems to be gold about these things. It's a silver bullet I've been looking for..
Like Jerry I've never heard of any downside with the small exception of BSF competing with worms for resources in compost systems (link). You could argue the worms are the invasive species here as they were all wiped out in the last ice age.

Author:  BelgianPup [ Thu Aug 15, 2013 8:44 pm ]
Post subject:  Re: Are BSF an invasive species?

From the National Invasive Species Council (NISC):

Preamble: Executive Order 13112 – defines an invasive species as β€œan alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.”

I haven't come across anything in the last few years that would indicate that BSF have any of those negative qualities. Everything they do is beneficial (except crawling out of their tub when I'm not looking).


Author:  HDC [ Thu Dec 10, 2015 3:49 pm ]
Post subject:  Re: Are BSF an invasive species?

In Belgium and The Netherlands, autorities do not object breeding BSF, since they are not regarded as invasive.

Author:  BorealWormer [ Thu Dec 10, 2015 4:41 pm ]
Post subject:  Re: Are BSF an invasive species?

HDC welcome to our forum :) If you'd like you can introduce yourself here (link).

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