generally speaking most butterflies are short lived in the adult stage- two to six weeks being avarage. Some of the same species live longer in order to migrate- monarchs for instance- some do the 2000 miles, some of them do it over the course of three generations- and we are talking generations four or five weeks apart. The first three generations live 2-6 weeks- the fourth lives for 6 or seven months- fascinating- read this
http://www.monarch-butterfly.com/
Some of our British butterflies have varying lifespans- the last generation of the year of the orange tip for instance will live long enough for it to hibernate-emerge the next spring, mate and lay eggs before dying.