Our first Anise Swallowtail (Papilio zelicaon) arrived in the garden today. We’ve had Western Tiger Swallowtails flit through from time to time, but the Anise Swallowtail is here to start a family, not just pass by. This species feeds on plants in the carrot family, and is one of the reasons that we planted fennel (other than for culinary purposes).
I spotted the butterfly just after she flew over the fence, thinking that she was just another Western Tiger Swallowtail, a nice butterfly but one whose food plants are large trees that aren’t in our garden. Then the butterfly dipped to circle a fennel plant. Not a Tiger Swallowtail typical behavior – they find fennel of no use whatsoever. I ran out the door and saw large black spots on the forewings: Anise Swallowtail! She did a quick aerial recon of the garden, then went from plant to plant, laying tiny yellow-green eggs on the leaves.
If no freak accidents happen, the eggs will hatch into tiny black caterpillars that look kind of like bird turds. It’s safer for them that way, since what predator would want to dine on bird turds? Later they’ll molt and transform themselves into black and green tubes with yellow accents that would look great as jewelry – if they didn’t insist on crawling off the chain to look for some fennel to munch (and leaving some pelletized plant material of their own).
Note: fennel is listed in California as an invasive plant, so make sure that you keep it confined to your garden and remove any unwanted seedlings. Our plants are in an urban area with no runoff into the storm drain system (thanks to the rain garden), so they can’t get loose. Although a hike along the American River will likely pass some well-established stands of the plant.
Updates:
July 10, 2011: The eggs have hatched into tiny black caterpillars. Really tiny, almost like thick black hairs.