The most common butterfly we have seen this year is the yellow swallowtail. Its distinctive yellow and black pattern is a constant in the garden flittering between the many flowers we have. But as the season wanes so will they. Now I see that a great many caterpillars have emerged, first on my celery plant then on my fennel. They are greedily chomping away, building up size and energy to enter the next stage of life—that of a chrysalises. I can’t wait.