Saturday, February 19, 2011

Papilio zelicaon--Anise Swallowtail

It is a little early for Anise Swallowtails to be laying eggs, but maybe they will start when the weather gets a little warmer. The eggs are small, maybe about the size of a poppy seed, very spherical and pale yellow when first laid. Can you see those dots on the fennel in the first pic? Those are eggs. They darken before they hatch. Then a tiny caterpillar, abot the size of a comma, emerges and starts eating its eggshell. When it has enough of that, it moves on to eating foliage. After molting (shedding its skin) several times, it grows into the large caterpillar shown in the second pic. Then it attaches itself to the substrate with a silken button and silken girdle, as shown in the third pic. This one is on the shingles on the front of a house. Next, it sheds its last caterpillar skin, revealing the chrysalis underneath. The butterfly forms inside and emerges, sometimes a few weeks later, and sometimes a few years. Sometimes people think of this last part of the cycle, when the butterfly forms in the chrysalis, as metamorphosis. However, to an entomologist, the whole process, from egg to adult, is metamorphosis. Insects change over their entire life.

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