I have a solid sided, open bottomed bin with a lid:
It sits on 8 pavers that keep the four edges up out of the dirt and discourage rodents from being able to invade it. At the bottom where there is no paver coverage in the center, a hole one foot deep is dug to collect any moisture from above and discourage any from oozing out from around the pavers. This hole, also, helps keep the moisture level in the bin higher by keeping the water I add within the space the bin provides. Also, it increases the volume of the bin and helps regulate its temperature.
I collect and put our kitchen scraps down in the exact center of the bin. Then I scatter a few inches of leaves on top to prevent any stray house flies that normally avoid the soldier fly brood from laying any eggs on the food. Soldier flies, however, lay their eggs on top of the leaves. Their larvae hatch out and crawl down to the food source.
[As time goes by, the pile of leaves gets deeper and deeper in cooler weather when they’re less active.]
I spray water on the pile to keep it as moist as needed. This keeps the Black Soldier Fly larvae in good shape. Plus, it facilitates the fungal progression of breaking down the leaves into compost (leaf mold). The effluent from the soldier flies stimulates bacteria to, also, aid in the composting process.
When the bin is full, I switch to my second bin. This takes about two years because the level keeps dropping as I use it because of the composting naturally occurring. Then the first bin then sits quietly. The last of the larvae mature and the female BSFs automatically switch to the new bin where fresh table scraps are added. I moisten the leaves only occasionally now in the first bin as the larvae finish maturing and crawl off. Keeping the bin’s lid after the BSFs are totally done with it helps cook the leaf mold. By the time the second bin is filled, the first bin’s soil has already been used by me and ready to begin again.
Note: I do not stir the leaves. I only just add leaves a bit at a time.
Note: The leaves I’m using in this process are Live Oak leaves which are very coarse. Typical leaves would decompose easily by standard leaf mold techniques, but Live Oak leaves require a bit more attention if one is impatient.
Note: During warm weather BSF breeding season, I leave the lid ajar so that they can come and go (and so the larvae can crawl away). Also, it keeps the bin from overheating.
Note: I do not collect the BSF larvae. Instead, they crawl off and provide a good source of food for the local toads, lizards, birds and such.
Note: Since no food scraps are wasted (as even the cooking grease goes into my compost bin), a bonus is that my curbside trash bin is never smelly nor does it attract house flies because the only food I ever discard in it is bones.
Note: No house flies ever buzz around my Black Soldier Fly bin. The experts say that the BSF larvae’s odor repels them. And, I’ll have to take their word for it, because my BSF bin is odorless. If you disturb the leaves in the bin, you only get the smell of damp leaves (a nice odor).
Black Soldier Flies:
What Is Leaf Mold:
If you’re interested in collecting the BSF larvae to feed chickens, fish, etcetera, there's a nine part YouTube series on raising Soldier Fly larvae for collecting them that is thorough: