This second brood of the year will go through the same life cycle later that summer, except that their eggs will not hatch until the following April. A species in trouble The diminutive Karner blue butterfly has fed on wildflowers in Wisconsin since the last Ice Age. At one time, Karner blue populations were found from Minnesota to New England. In modern times, the butterfly's populations have become increasingly rare in much of its national range, and it is increasingly vulnerable to extinction. Karner blues are completely dependent on the wild lupine as their sole food source during their larval stage.
Wild lupine grows in open sandy areas that can contain some trees.
Lupine habitat becomes more rare as other vegetation grows and shades the stand. Sunny locations are also developed by people. This listing began a program to recover Karner blues across their entire national range. Interest in saving the little colorful flit brought together a diverse partnership of public and private groups who have developed a remarkable and flexible conservation plan. The plan helps Wisconsin landowners and land managers continue routine land uses in areas where Karners live while protecting the butterfly and still complying with the Endangered Species Act.