That's a strange question! Have you found one, or is this another exam question? If you found any on a plant, then that's where the butterfly or moth laid the eggs, so that they can eat that particular plant's leaves.

Different kinds like different plants! Some can only eat one species of plant, others can eat any plant in one plant family, and a few seem to be able to eat a wide variety of plants.

my ornamental cabbages lol I have a full-time job catching the blighters!!!!

My first geraniums of the winter have got 'em, too. So-called "tobacco budworm" in this case--also attacks geraniums and petunias.