Around April 5, I caught a glimpse of a butterfly in my garden and ran out to get a closer look. I really couldn’t miss it since it had a wingspan of over 5 inches. It fluttered about my garden rue and then took off over the fence. I didn’t see any eggs just then but a week later there were tiny specks that might be larvae! By April 19, there were four “orange dog” caterpillars of the Eastern Giant Swallowtail, Papilio cresphontes. They look like bird droppings to deter predators.
I have grown Ruta graveolens since becoming a Dallas County Master Gardener in 2006 and love its blue-green foliage and tiny yellow flowers. Along with various trees it is a host plant of the beautiful Giant Swallowtail larvae. The adults visit my garden every year but these are the first caterpillars I have seen. Photographing the adults is challenging as they are always in motion, fluttering away as they feed.
Then last fall I noticed this mating pair on my Loropetalum bush right at eye level. These are distinctive from the Eastern Black Swallowtail adult in that the and the row of large yellow spots on the dorsal (top) side meet in the middle of the wing rather than near the bottom and the ventral view is mainly yellow.
As of May 2, the four caterpillars have grown to over 2 inches and should pupate soon. The chrysalis stage is variable but usually takes 10–12 days. I hope to photograph at least one chrysalis and adult as it emerges. With luck they will return to my garden rue to produce another generation in the fall. Bugguide.net states they overwinter as a chrysalis.
Caterpillar Hosts: Trees and herbs of the citrus family (Rutaceae) including Citrus species, prickly ash (Zanthoxylum americanum), hop tree (Ptelea trifoliata), and Common Rue (Ruta graveolens).
Adult Food: Nectar from lantana, azalea, bougainvilla, bouncing Bet, dame’s rocket, goldenrod, Japanese honeysuckle, and swamp milkweed. Here’s one feeding on clammyweed last summer.
Grow Common Rue and you might have these interesting and beautiful garden visitors!