What did sycorax do to the sprits who disobeyed her?

In Shakespeare's play "The Tempest," Sycorax, the witch and mother of Caliban, punished the spirits who disobeyed her by imprisoning them in trees. This act of confinement was a means of exerting her control and ensuring obedience from her magical subjects. The spirits, bound in this way, suffered until Prospero arrived on the island and freed them.