Something has claimed my beach wormwood (Artemisia stelleriana) and I am happy about it. It’s the larva of the American Lady butterfly (Vanessa virginiensis). I see all stages of larva development on the plants but the full-grown caterpillar is a wonder to behold. The one below is almost an inch and a half in length and has rows of bristle-like spines, yellow and black stripes, and red, orange, and white spots on each body segment.
The artemisia cultivar I grow is compact, growing about 8″ tall and planted along the edge of a border, a great accent with its downy soft silvery leaves. It looks a lot like dusty miller but unlike dusty miller, this plant is a hardy perennial in the Seacoast of New Hampshire. It’s a perfect little groundcover.
But this season it won’t look so perfect…. especially at the tallest tips, the blooms. The smaller larvae have spun silk around the bloom tips and smaller leaves. They use these safe hideaways as protection from predators during the day. The larger caterpillars have nests lower on the plants. It’s a bit messy inside there, full of excrement or frass.
The plants are pretty much covered with larvae, many at an earlier stage of development. I’ll have to wait to clean up the plants after the larvae have developed into pupae, then emerge as adult butterflies. The artemisia will survive. After the butterfly season ends, I’ll heavily trim the ragged plants and new growth with begin to appear.
Soon we will be rewarded with the beautiful American Lady butterfly, a medium size butterfly of deep oranges and black spots, closely related to and often mistaken for the Painted Lady butterfly. It lives for two to three weeks during which time it mates and reproduces, starting the cycle once again…. and will eventually begin their fall migration, riding the winds southward just like the Monarchs.