These adults breed, laying their eggs on the wild lupine during June. The second brood emerges as adults in mid-July. The reproductive success of the adults of this brood will largely determine the size of the population the next spring. The Karner blue butterfly was listed as an Endangered Species in December, 1992. An example of the decline experienced by this butterfly is seen in the Albany, New York Pine Bush population, which declined from 80,000 butterflies in 1979 to fewer than 200 in 1990.
All butterflies undergo a series of stages of development.
The female adult butterfly lays an egg from which a caterpillar emerges. The caterpillar eats, grows, forms into a pupa , which metamorphoses into the adult butterfly. Losses of these plants and their habitats diminish Karner blue butterfly populations. Karner blues seem to prefer wild lupine plants growing in open, sunny areas. These areas were once kept open by fires that killed many of the shade trees and shrubs.