Seeing many of those butterflies tottering on the ground we realized we were witnessing the Ending Of Life - and in large numbers. As if all of these beauties have appeared on the same day, they were now all dying in the same span of maybe two days.
Nature is uncanny.
Nymphalis antiopa, known as the Mourning Cloak in North America and the Camberwell Beauty in Britain, is a large butterfly native to Eurasia and North America. (Wikipedia)