In a saucepan, combine 1 1/2 cups blueberries, sugar and tapioca over medium-high heat, stirring frequently.
Once the sauce starts to thicken, remove sauce from heat.
Off the heat, add remaining 2 1/2 cups of blueberries and stir to combine.
Pour into baked and cooled pie shell and refrigerate.
Meanwhile, whisk together pudding and milk until thickened.
Fold in Cool Whip.
Top blueberries with pudding mixture and chill for at least 2 hours.