The polydamas swallowtail caterpillar population has exploded in the garden. I watched the polydamas swallowtail lay eggs on my birthwort, which is now crawling with tons of caterpillars.

The polydamas swallowtail caterpillars feed in groups when they are small, devouring the youngest leaves, as well as flowers before moving onto the older portions of the plant.

The caterpillar will go through four instars, 19 to 24 days, before it’s ready to form its chrysalis. The colors of the caterpillars are a bit different during the first instar, with tan and small tubercles. Once the caterpillar molts into the second instar, they become dark brown with larger tubercles.

They have a black head, prothorax top is orange and short dark stripes. Once the caterpillars enter the third instar, the caterpillar becomes smoother with a glossy appearance.

The caterpillars grow up to 2.1″ in length