 Actually, I was very surprised because these butterflies do not occur in South America. So they had to be migrants in some way. What did you see on the beach that shows you that these butterflies were exhausted? How did they look? They were really standing with the open wings in the sand. That's a very strange place for a butterfly to stand. You never see butterflies very rarely standing on the sand of the beach. They usually stop in the vegetation. They hide at night or they go to flowers to feed themselves.