green frog, industry
黽 centers on a green frog, and by extension, the idea of persistent effort or industry, perhaps from the frog's tireless hopping or its association with diligence in some contexts.
黽 is a pictograph of a frog, with the modern form retaining a stylized head, body, and legs. The exact historical development is uncertain, but the frog origin is broadly accepted.
The shape looks like a frog with a wide head, squat body, and long back legs. Picture a green frog industriously hopping from task to task.
For ボウ, imagine a frog wearing a tiny bow tie while working hard: bow -> ボウ, and the frog's industry is rewarded with a bow.