Hazelwings

Hazelwings are a sort of fairy that closely resemble large bees.  Their life cycle is extremely unique, as they are born in large numbers as a sort of insect, behaving much like bees do, including living in hives.  Once a hazelwing hive reaches a certain critical mass, they aggregate together, consuming much of their honey in the process, to create a single, "full-sized" fairy.