PREHEAT oven to 400°F. Mix berries, sugar and tapioca in large bowl. Let stand 15 minutes.
PREPARE bottom pie crust as directed on package for 2-crust pie, using 9-inch pie plate. Fill with fruit mixture. Dot with butter. Cut second pie crust into 10 (1/2-inch-wide) strips with pastry wheel or knife. Place 5 of the strips over filling. Weave lattice crust with remaining strips by folding back alternate strips as each cross strip is added. Fold trimmed edge of lower crust over ends of strips. Seal and flute edge.
BAKE 45 to 50 minutes or until juices form bubbles that burst slowly. Cool.