They get dark when they are ready to go off to find a good place to hide away while they pupate. They evacuate their digestive systems before they crawl away and do not continue to eat. Guess they don't like to go to bed on a full stomach.

Try the following link

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

I have EFs and BSFLs in the same box in my garage. Without a lid on the box they can fly off, mate and come back to the box to lay the eggs. This works great.

http://s682.photobucket.com/albums/vv188/steamyb/Worm%20Bin/

Well, my verdict is BSF are unsuitable for inside bins. I had hoped to be able to retard the pupation process. It seems that the mature larvae are just too active and I can't have them escape, pupate and have mature flies in the house.

It is far too hot here (around 100) to keep my worms in my garage so I have moved then indoors. The BSF larvae are thriving in the hot environment. I certainly don't want hundreds of adult BSF's in my closed garage either. They wouldn't be flying off and mating, they'd be littering the floor with dead flies.

It's not worth the effort to separate the semi-processed larvae bedding to feed the worms. I can't risk missing a few maggots and have them turn into flies in the house. My wife would end my worm project then and there..