But these areas aren't enough to sustain the Karner blue alone. If you don't have the plant, you won't have the butterfly. Karner blues do need other plants in addition to wild blue lupine. The oak savannas, pine barrens, and dry prairies where the butterflies live are predominantly open spaces, as too many trees crowd out the plants Karner blues need to survive. This mosaic of sunny and shady areas, combined with dry, sandy soils, permits the butterfly's sustaining plants to thrive.
Butterflies have such interesting life cycles, transforming from caterpillar to butterfly.
Karner blue butterflies complete two life cycles per calendar year. The first-flight butterfly larvae emerge in April from eggs that were laid on or near lupine the previous summer. The larvae tiny caterpillars just a few millimeters long crawl up the lupine plants and begin to eat the leaves. These larvae are often accompanied by ants, which are probably attracted by a sugary substance that the larvae secrete. The ants collect this solution from the larvae and seem to play a role in protecting the Karner blue caterpillars from potential insect predators.