As new as I am, and posting this without researching first. The BSF look very close too what's called a Robber Fly down here.
However, the robber preys on other flys, but judging by your images, I have had BSF present, albeit unintentionally.(Sic), based on the "dark" stage of development, that i've come across.
I read on yours, & other other posts about the waste breakdown, and down here we fit in perfectly, Rural, Semi-Rural and Developed, loads of opportunities.
I did manage a pot in the "Veldt" open grassland and we'll see what happens.
Before I give feed back, just a thought, our Winters drop to about 4C, at worst 1C. Currently were at 12C @ 1300m high.
