"Feller bees will carve deep into living trees to make their nests, presumably to avoid having to talk to the Forest bees."
Codey's Notes give the following hint:
"This forest species likes to store acorns and the sticky pearls produced by Forest Bees for food in the winter."
It has a 39% of spawning.
When a Feller Bee is selected in a Habitat and is given enough of the items it likes, they will leave when their visit finishes.