Perhaps the critter has been determined. This evening we spotted a newcomer, a raccoon, truckin' across the yard. After googling one of the first responses was "

Guard Your Garden: Raccoons - Official Blog of Park Seed", which said that they can destroy your flowers. Admittedly this raccoon was out not at night, but toward dusk, but walking through our perennial garden. The Calibrachoa was munched nocturnally, so...

Raccoons are nocturnal. If you saw one at dusk, it was just getting started for the night.

Martha

If you see a raccoon during the day, it probably has Rabies.

PlantSkydd will repel raccoons, too, and NO! I do not sell it! :) I just hate spending $$$ on Plants for the 'wildlife' around here!

Rats love calibrachoa (and pansies, and lobelia, and tomatoes....).

I'd suspect ground hogs or deer if any are in your area.