This year was a great year for butterflies in our area and many mornings I counted 10-15 butterflies in my garden at one time. Most of these were tiger swallowtails but black swallowtails, buckeyes, and monarchs occasionally visited. My butterfly bush, pink cone flowers, garden phlox, lantana, and verbena ‘Homestead Purple’ seemed to draw the most butterflies but more was going on than I realized.
One day I began to notice some unsettling changes in a few of the other plants; half the rue was gone and large areas of the fennel had also been eaten. A few days later I noticed that the part of parsley growing outside my kitchen door was mostly stalks with few leaves. Upon closer examination I found the culprit, the caterpillar of the black swallowtail butterfly. It is very striking in its appearance and looks like a miniature dragon with its green, black, and yellow striped body and the orange forked gland on its head. The gland is a defense mechanism that secrets a foul smelling substance to repel enemies. After watching this critter eat I understood why my fennel, rue, and parsley disappeared so quickly. Take a look at this real time video to see what I mean. The speed at which this guy can eat is amazing.
The black swallowtail caterpillars like the members of the carrot family so dill, carrots, and Queen Anne’s lace are also favorites but Bishop’s weed and members of the citrus family including rue are also foods of choice. The rue, fennel and parsley in my garden that were stripped by these critters grew back very quickly and the plants remained vigorous and healthy but I plant extra parsley every year so that I can accommodate a large number of caterpillars and still have parsley for myself. Hey, what’s a plant or two, or three among friends?