This is Steve Heffernan’s explanation for why unripe bananas are so sticky and not sweet at all.
Apparently bananas serve as host to colonies of minuscule sticky bugs, which feed off all that sticky, bitter syrup in the unripe banana’s peel and, well, excrete sugar. So as the banana matures, the colony continues to grow and convert unpleasantness to happy yumminess.
(The facts are not quite clear on whether the colony ever leaves the banana, or if you get to eat them too as an added bonus.)