Objective: How do you prevent cranberry fruitworm?

Which of the following solutions is more sound in terms of naive physics reasoning?

Available options:
A). Observe the cranberry plants daily for the presence of grey moths. If you notice any, you must spray the whole cranberry plot with an insecticide to kill the eggs before they hatch.
B). Observe the cranberry plants daily for the presence of grey moths. If you notice any, you must spray the whole cranberry plot with an herbicide to kill the eggs before they hatch.
A).