Leaf shaped wings and yellow-green color makes this butterfly a camouflage master. This ability helps him hide during hibernation period, as butterfly leaves for thirteen months, and survives winter period. Hibernation helps him during difficult summer period too.
The fact that Gonopteryx is one of longest living butterfly explains his appearance in early summer and late autumn. I even heard that he can survive for two or three years, but that is probably just a rumor.
While males are yellow, their female partner is brighter and greener.
Even though it is 14th November, I saw this butterfly today flying together with Colias alfacaiensis, Colias croceus and Polygonia c-album. It looks like they did not care about upcoming winter :)