Have you known that this larva is a real aphid killer machine? It eats one aphid after another the whole day.
So this larva is sold by some shops and you can buy it for your garden if you've a problem with aphids and don't want to use poison.
A Common Milkweed (Asclepias syriaca) Roadside Story: Monarch Larva (Danaus plexippus) Alleyn-et-Cawood, Québec, Canada:
It's a story that plays out From Canada to Mexico each year and is loverly to document with your cameras.