When Caliban was lazy and neglected his work, Ariel (who was invisible to all eyes but Prospero's) would come slily and pinch him, and sometimes tumble him down in the mire; and then Ariel, in the likeness of an ape, would make mouths at him. Then swiftly changing his shape, in the likeness of a hedgehog, he would lie tumbling in Caliban's way, who feared the hedgehog's sharp quills would prick his bare feet. With a variety of suchlike vexatious tricks Ariel would often torment him, whenever Caliban neglected the work which Prospero commanded him to do.
make mouths at =make a face at?