Casters
Casters are a chrysalise form of maggots, which is the last stage before they become a fly. Their crunchy shells are believed to be one reason they are liked so much by most species of course fish.
It is believed that when they are loose fed with maggots they will bring in a better quality stamp of fish. They are becoming more popular when shallow fishing for Carp, as they make a loud noise when they hit the surface of the water.