White worms, also called Pot worms.
http://www.redwormcomposting.com/worm-composting/ive-got-white-worms/

Harmless, if you have LOTS of them can mean your bin is getting a little acidic. Starch and breads also seems to very popular with them. As with everything, have plenty of bedding and thus air flowing around and you should be fine.

The bin enviornment has been made ideal for them. They are working for you. If more food is added with no dry bedding they will keep working. Or maybe add some vermicompost back onto the top of the bin along with some dry bedding material. Cardboard would be good. Maybe put food waste into the outdoor bin for a week or a month until the white worms are gone.

I feed them to our fish, they love them!