Beezley

From the Super Mario Wiki

Beezleys are the bee enemies appearing in Wario Land 4. They sting Wario, so he'll become Puffy Wario. Their first attempt in a level is in Wildflower Fields, the second level of the Emerald Passage. They also appear in Arabian Night of the Sapphire Passage Only when Wario comes in a pipe with a bee icon with a room full Spike Balls. When falling in, these foes transform into Beezleys. They are needed in the room to get to a pipe that the enemies transform into Miniculas to get treasure.

If a Beezley goes into a Money Flower, Wario can get as many coins as he can. However, the flower will dry out and transforms into a coin.