I had never heard of a blue monarch, but I looked it up and there is such a species. However, it doesn't have much true blue from the pictures I saw. There are bluer butterflies...
Blue Monarch Tirumala petiverana (an African species):
https://www.inaturalist.org/ta...
Other blue butterflies:
https://australianbutterflies....
The above website says there are no true blue pigments in plants, but I disagree. Certain anthocyanin pigments in flowers are blue.
