They're not a bad feeder. They just don't have a lot of meat on them. They're not very big. But they have the highest natural amount of calcium inside them than any other feeder. Because of this, they're used mostly to feed females who are either gravid or just recovering from laying. The egg shells are made mostly of calcium, and if they don't have enough, they'll take it from their own bones. So it's good they get it from external sources.
They are the same thing as phoenix worms, just a different brand name. I have been wanting to try them, but the ones at my local ***** are always dead.
If they are small then simply warm them up to 80-90 and give them a hotdog......if they are cream colored and not black yet (they turn black when they are getting ready to pupate) then they will grow very quickly.....mine that I breed are 1 inch and very fat.