Cabbage white caterpillars.
We popped a couple in a rub a few years ago with some nasturtium leaves and within days they'd formed their cocoons on the lid. The kids were young and loved checking each day and seeing the changes in the cocoons until the butterflies emerged and we set them free. Except for my youngest who loathes any insect!!!
If you've got walls, sheds or any building near the nasturtiums check for the cocoons appearing. Quite a fascinating process. I never bore of it; just like tadpoles to froglets.
I can't make out your camera photos - what did the cat drag in?