Don't know the answer about cocoons but there's a good thread about BSFL in these forums at the link below.

Here is a link that might be useful: All about Black Soldier Fly

Too many BSF larvae can cause the bin to heat up too much for worms. I dont' have any experience of them myself- but at the rate they seem to grow and break down material- you can imagine how much heat they'd have to generate.

I can't be too sure as I don't have a scientific method to measure it, but I've had my worm bin for a year and "innoculated" it with BSFL about a few months into it. Just harvested the worms the other day and saw plenty of little babies, and there were ALOT of BSFL, so I'm positive that they don't really have an appetite for worm cocoons

No, BSFL won't eat cocoons, based on my observations, anyway.

If you're talking about adding 50 individual larvae to a bin with a thousand or so worms, have at it! But you should be aware that adult BSF will attempt to lay eggs in any container holding healthy and happy BSFL.

Also, BSFL break down a lot of material, quickly, into a small quantity of worm treats _and liquid_. So check your drainage while you're checking your bin's integrity.

Best wishes from a half-reluctant BSFL caretaker,

DSF
http://bokashislope.blogspot.com

I opted to not put them in with my EF's. I had moved my adults from a small colony of hortensis though to a smaller bin inside the house. I thought it was too hot in the garage and that was why they didn't seem to be breeding. The BSFL's went into that bin. Maybe a hundred or so. I doubt that adults will be able to get in there to lay more eggs.

I'll be curious to see how much these little bugger can eat. They seem to be tearing through my outside compost bin. So much so I decided to test it with a squirrel that was unfortunate or dumb enough to get trapped in the havaheart trap i put by my veggie garden.

There are great time-lapse videos on youtube of BSFL devouring hamburgers or rotten fish. Pretty awesome!

I had them in my worm bin last year, this year they're in my ''cooking'' compost pile. I've seen lots of adults hanging around the worm bin, but no larvae. Probably not wet enough for them.

The folks over at the BioPod forum are trying to build a reference source for people trying to learn if BSF are present in their area. If you've got a minute consider posting at the link below.

Here is a link that might be useful: Confirmed Black Soldier Fly Sightings