Bumblers are bees in Grassy Greens from the game Mario Pinball Land. If Mario goes near a Bumbler, it tries to chase Mario, with its stinger facing the direction it goes in. Being stung will cause Mario to go out of control, and he must hit its back instead to defeat the bee. Bumblers will give up after a time if they can't sting Mario and return to their original position.
Bumblers will only appear in the second part of Grassy Greens, with the windmill where Petey Piranha awaits. Bumblers also appear if Mario hits the beehive near the windmill, where three of them come out. If ignored for a long time, Bumblers will retreat back to their hives. Mario has to defeat all three Bumblers if he wants to earn a Star.