Sounds like Black Soldier Fly larvae in you outdoor bin.
They are the good guys, but are showing that there is more food in your bin than the worms can keep up with.
You don't say how many worms you started with.
Once you move outside you will invite all creatures out there.

Startrd w/ 1# a couple of months ago & feed about once a week..
will still pick up all these critters even if the top is always on the bin
will the larvae ever die out or is this a persistant problem

I had these a while back, too. They are what made me decide to move my bin outside. I spent a bit of time removing the adults, and they haven't come back. My bin is quite a bit drier now than it was before, so that might be why there hasn't been another population explosion.

If you can ignore them, they aren't a big problem. If they bother you, I have read that you can put a piece of bread in the bin to attract them, then discard the bread when it is covered in maggots. I prefer to just let them grow up and fly away.

Hey Jenv, are you saying you had BSF when your bin was inside?? Oh, oh, I haven't heard that one before. My bins are in my spare bedroom in my apartment, and I don't want anything bizarre in my apartment, for obvious reasons.

Yep, I had BSF when the bin was IN my house. Once I figured out what they were, I put the bin in a spare room and shut the door. I vacuumed up many flies every day for about a week, then moved the bin to my garage when they stopped appearing. I haven't seen any more since. The larvae all stayed inside the bin, but there were a few flies wandering about the house.

I would like to bring the bin back inside, but DH still isn't clear on what is in the bins, and I don't want to have a fight over worms in the house. If they do come back in, the bin will have a drape of mosquito netting put over it, to contain any adventurous decomposers.