"The Borrower bee sneaks into social hives to take honeycomb for its own nest: the other bees don't confront the Borrower's comically bad disguises out of pity."
Codey's Notes give the following hint:
"This swamp species likes to 'borrow' honeycomb from other bees, and will nest itself near beehives to keep a constant supply."
It has a 35% of spawning.
When a Borrower Bee is selected in a Habitat and is given enough of the items it likes, they will leave when their visit finishes.