So I re-did the bins. The plastic bins were good enough, and I'm still using a scaled down version of the most simple, but I felt I was ready to go 'large'. We built this bin with plans from Northwest Worms, and while I don't think the plywood will last a long time, it's a good prototype to work from. What we use in the bins is just too wet I think and will eventually rot the plywood out. But I like the design, and so far it's working well. We put about 3 inches of coconut fiber as substrate, but now I'm changing it out gradually with more textured / chunkier pieces of coconut husk chips. Again our mix is wet and the coir is packing down more than I'd like.
This is what came out of the plastic bins, looks tempting doesn't it?? I put about ½ back in and let it sit for a couple of days until they'd eaten out the fresh stuff.
I'm learning all the time from these bins (I hope). My main issue right now (and always) has been how to remove the compost from the bin without taking so many bsfl with it. I'm tending now to add food like I would to a regular worm bin, hoping the grubs migrate and I can gradually remove the 'compost'. What I've read online about 90% of the feed being converted into larvae and only 10% waste / compost, isn't my experience. I think perhaps it could be to do with the feed. I'm feeding fruit and vegetable peelings, fallen fruit and culled fruit - so a wet sloppy mess mostly that's probably got a fair amount of fiber. Keeping the bins dry has been an issue, but I'm putting in cacao chaff which helps.
What I read on the forums is that most people - at least who post - are in the north and only clean out their bins at the end of the season: my bin fills up too quickly for this. So for now I am taking out the compost which most of the grubs have left and putting it in with the chickens to pick through before adding it to my compost pile. It's working, though of course I'd rather harvest the pupae.
My other bin is a 5 gallon bucket and hangs from its handle in the rafters of the chicken run. Each morning and evening I scoop chicken poop / some shavings into the bin which is populated with bsfl. Once a week I empty this bin into my compost area and begin again. It's far too strong to put directly on the garden and it's full of bsfl. I'm not going to feed these back to my hens (clearly), but use these to keep up the local population. So far I like the system: the coop and run are clean, odor free (almost) and my compost is sped up considerably.