You may need to use a heavy object, plate, to hold the broccoli underneath the water to soak out the worms, like PytnPlace says.
There is an insecticide that is completely acceptable to organic food growers and that is BT also know as Bacillus thuringiensis or Dipel.. It is a natural control for caterpillars, worms and larvae. It is harmless to people, pets, fish and other beneficial insects. You need to spray it at correct times for it to be effective.
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