This series of pictures shows the complete life cycle of the monarch butterfly. The first picture (I) shows a single egg which was laid by a monarch butterfly on the underside of a milkweed leaf. The next two pictures (II, III) are the monarch caterpillar. Both "ends" are shown. During its larval stage the caterpillar eats milkweed leaves and its milky sap almost non-stop. It is the "milk" that will make this butterfly distasteful to predators. The fourth image is what the caterpillar left behind while creating its cocoon. The cocoon (V) of the monarch is a light green with beautiful gold and black detail. The caterpillar stayed in the cocoon (pupa stage) for approximately a week. In this specific case, 7 days. Overnight, the bright green cocoon became transparent. Here (VI) you can see the pattern of the wings through the walls of the transparent chrysalis. Finally, the pupa case split open and the butterfly emerged, hanging upside down to dry its wings. The "plastic" open cocoon is left behind. Several hours later the new butterfly still was getting used to its new wings.
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Caterpillars are the larval stage of butterflies and moths. Several caterpillars are shown here.
The lepidopteran larvae that made this trail is refered to as a leaf miner. This species of larva Phyllocnistis populiella burrows in the leaves of poplar trees. This particular leaf is Populus tremuloides, commonly known as quaking aspen. The width of its excavation is the light-green "mine shaft." The dark line is the excrement it left behind. The adult of this larvae is the Leaf Blotch Miner Moth.
