The gardener, being Man, and Man being the sum total of his choices - made of hundred of thousands of bits and pieces, each responding to and acting on a separate impulse - was not a bit surprised when one of his more impulsive bits chose to abandon him.
The piece-of-the-man among the bugs suggested an inquiry into the death of the caterpillar. Declaring that he alone among the bugs was self-aware, could read and write, and had an opposable thumb, the piece-of-the-man nominated himself judge. Being the only one present who could count, the piece-of-the-man also seconded and thirded his nomination to no objections.
(cake for everyone!)
Some light was shed on the mystery by the firefly, who recalled an attraction to an illumination, a flash of light. The firefly swore that there were TWO caterpillars in the garden that night.
Alas, upon cross examination, the promiscuous firefly was determined to be a less than ideal witness.
(it's a reading light, i swear!)