What it is
Maggots catch roach, F1s, carp, tench, bream, perch and the rest. They work on the waggler, the feeder, the pole and the whip. They also attract every small fish in the county, which is both the point and the problem.
Bronze, red and fluoro all have their days. A pinch of fluoro maggot on the hook can pick out a better fish over a bronze feed. In winter they are often the only bait a commercial F1 wants. Keep them cool, keep them dry-ish, and don't let them pupate into casters unless you mean them to.