Relatively easy? :D

Of the 3 you mentioned, prometheas are the "easiest" to find but don't count on coming home with a bag of cocoons.

If you are looking for multiple hits in one outing, I suggest someplace with many acres of trees that has lots of trees with low branches. Trees need to have dropped their leaves because you are looking for the odd thing that has not dropped for some reason.

Sometimes polys connect their cocoons to the branch while other times, they are content to have their leaf/cocoon drop to the ground. Makes for fewer of them to be found hanging in the trees.

Thank you!