These adults mate, laying their eggs in June on or near wild lupine plants. The eggs hatch in about one week and the caterpillars feed for about three weeks. They then pupate and the summer's second generation of adult butterflies appears in July. These adults mate and lay eggs that will not hatch until the following spring. Feeding Habits Karner blue caterpillars feed only on the leaves of the wild lupine plant.
Adults feed on the nectar of flowering plants.
This severely restricts where they can survive. Range Karner blue butterflies are found in the northern part of the wild lupine's range. The butterfly is most widespread in Wisconsin, and can be found in portions of Indiana, Michigan, Minnesota, New Hampshire, and New York. It may also be present in Illi nois. Habitat Loss or Degradation Habitat throughout the range of the Karner blue butterfly has been lost as a result of land development and lack of natural disturbance, such as wildfire and grazing by large mammals.