What kind of worms? for feather dusters I feed them marine snow every other day or, live plankton. im pretty sure you dont have to feed them. most likely they will eat stuff out of the water. they are filter feaders.
I have had one feather duster for almost 4 years. Never fed it anything. It does just fine filtering stuff out of the water. And I don't add DT's or Marine Snow or anything like that.