California pipevine, growing in the MAGC propagation area.

In many cases, discovering that something has chewed through your garden is a cause for concern. Sometimes, though, it’s a reason to celebrate, as when caterpillars take up residence on their way to becoming beautiful butterflies. You may have even planted milkweed in specifically to attract Monarchs, which famously migrate thousands of miles from North America to Mexico and back, and which only eat milkweed along the way. Here at MAGC this spring, we hosted the caterpillars of Pipevine Swallowtails, which similarly develop only on a single type of plant. California Pipevine contains toxins in its leaves that build up in the caterpillars so that they and the mature butterflies are themselves toxic, hence the dramatic warning coloration. Like all butterfly caterpillars (most moths spin cocoons), when Swallowtail caterpillars grow to their largest size, they shed their too-tight skin for a chrysalis, and undergo a transformation into a butterfly. This remarkable process actually begins when the caterpillar is still forming inside its egg, and continues under the protective cover of the chrysalis. The caterpillar essentially dissolves and its tissues reform as a butterfly, which then bursts out of the chrysalis and is shortly ready to fly away to continue the important work of pollination and of course, breeding new butterflies.

A caterpillar feeding on pipevine

A chrysalis on the wall of The Studio at MAGC

California Pipevine Swallowtail (stock image)