The protective case surrounding the pupating caterpillar can take many shapes. It is usually brownish green in color, and may be speckled to aid in camouflage. With few exceptions, butterfly larvae pupate above ground, usually attached to a leaf or stem by a silken thread. Inside the chrysalis the pupated caterpillar gradually transforms into a butterfly. The process takes two weeks for some species, and as long as several years for others. When fully developed, the butterfly inside the chrysalis swallows air, inflating its body and splitting the pupal skin. An adult butterfly struggles out shortly after dawn, its moist wings hanging limply from its thorax. Crawling to a place where it can hang by its legs, the newly emerged butterfly pumps up its wings by swallowing air, increasing its internal pressure and forcing blood through tiny veins in the wings. Within several hours the expanded wings dry and harden. At about the same time the butterfly excretes waste products accumulated during pupation. The butterfly is now free to begin the adult part of its life cycle.