When I was young I kept a pet caterpillar. I found it on a tree at recess. I carried it around with me, everywhere I went, for a month or so. I did not know the species nor was I particularly entomologically inclined at the time. It was not host-specific, and I would go into the garden to find an assortment of leaves and plant matter for my little friend, bringing it a haphazard salad. I remember holding it in my hands and let it climb over my fingers. At their tips it would dance, swaying the front of its body and legs in search of a new structure to climb, a new thing to explore.
One day I woke up and didn’t have a pet caterpillar anymore. Instead a dusty and webby pupae was stuck to the side of the jar, yellowish white and ghastly. I went on my father’s outdated PC with its comically large monitor. I found photos of my caterpillar and its pupa on a site about invasive pests. The moth it would have become was most notably harmful to native fruit trees.
I took my companion and friend outside and used a stick to place the pupa on the stone steps leading into my house, and crushed him underfoot with a sickening pop. It left a stain on the stone for a year, and on my conscience indefinitely.