From the Super Mario Wiki
Armored Stingas (アーマードスティンガ) are members of the Stinga species covered in armor. Armored Stingas attack like unarmored Stingas, flying toward Donkey Kong. They are also defeated like them, though when the Sound Wave Attack is use on them, they will turn into normal Stingas. They will provide Donkey Kong with one beat when defeated.