I suspect we'll be making our own upgraded black-soldier-fly bin next year. The bin we bought
is an awesome introduction...but I keep overfilling it since I have 50
pounds of moldy chicken feed to work my way through. Last week,
the mass of decomposing chicken feed heated up so much that white larvae
crawled off, and even when I'm more careful, I feel like the bin is
getting waterlogged and full of castings when I add half a gallon of
chicken feed (soaked to become about a gallon) per week.
The photo above shows the
kind of crawl-off I'd rather see --- just the black pupae. This
type of heavy harvest comes about once a week, when I add more chicken
feed and soak the bin contents in the process. On other days, I
instead get perhaps a couple dozen pupae, still enough to make our
tractored hens happy. But more pupae is definitely better, and I
now understand why you might want to have a 10- or 20-gallon bin.
Or perhaps to have several smaller bins (although I'd still want them
all to be located right outside the back door where it's easy to put in
scraps and to take out pupae for the chickens).
Meanwhile, there's at
least one feature of our current bin that I don't feel is working as it
should. The velcro strip around the top of the bin, meant to keep
pupae from escaping without crawling into the collection bin, has a gap
in each corner just big enough for pupae to wriggle through. I
keep finding drowned pupae in the ant-trap moat around the bin, which makes me sad.
While I'm writing a wish
list of future changes, I'd like to drill holes in the top of the
collection jar just large enough for an adult fly to escape, but too
small for a pupa to get through.
Three times now, I've seen adult flies trapped in the collection bin,
once because I left a pupa inside too long and it hatched, but twice
because the flies went to lay their eggs in the main bin and ended up
exiting in a different direction.
That said, our bin is
providing a healthy dose of animal protein for our flock nearly every
day, and the number of larvae inside seems to keep growing. I
caught one fly laying eggs inside the handle of the drainpipe last week
(which I transferred to the bin), but I suspect there have been many
other sets of eggs laid without my notice. I'm definitely ready to
say that Mark is right --- black soldier flies are a good fit for our
farm. Now we just need to work the kinks out of the operation.