Grumble Bee was a bee monster created by Finster after Rita Repulsa saw Billy's rage over getting a B on a science test. Grumble Bee was too powerful for Blue Ranger to handle alone, so Yellow Ranger came to her friend's aid. Grumble Bee could shoot greenish-yellow venom which could eat through anything, including the Blue Ranger's suit. He also had vibrating wings that could send yellow pulses of energy through the air that would hurt the ears of anyone who heard the ultra-sonic sound. Later he grows giant, and was defeated by the Megazord's Power Sword.