Autumn is harvest time, and this past weekend I was privileged to participate in a grape harvesting adventure at the old Clearspring No. 4 School, which is being slowly converted into a winery. Armed with clippers, about 25 of us descended on the vineyard to harvest the grapes and dodge bees. Fortunately it was cool so the bees were lethargic. They were also drunk, having helped themselves to a good deal of fermenting grape juice already that morning. I only heard of one reported bee sting that day.
Aside from bees, flies and ants, we encountered one other creature who is partial to vineyards: Eumorpha pandorus. This moth is part of the sphinx moth family which also includes the tomato hornworm, and the tobacco hornworm, and the hummingbird moth. The worms are the larval stage of the moth, and it was the larva of the Pandora sphinx moth that we saw. It’s a very strange caterpillar, which can grow to four inches long. They are green or orange with white spots. The hornworm name comes from a treacherous looking but harmless horn that adorns these caterpillars in their early instars, but on the Pandora moth it disappears after the third molting and is replaced by a button.
These moths are found throughout the eastern U.S. and south eastern Canada. The larvae feed exclusively on grapevines or Virginia Creeper. (That’s the vine that looks much like poison ivy, only it has five leaves and is perfectly benign.) The adult moths feed on nectar from various flowers. They are most active as dusk but can be seen flitting through gardens occasionally in search of nectar. Like many other moths they are attracted to lights after dark.
The Sphinx moth starts out life as an egg laid individually on a leaf. A small hairless worm hatches out and feeds on the leaf. These little worms are called an instar and they molt five times. The first instar molts into the second instar and so forth, growing much larger with each molt. Each stage may last only four or five days. The fifth instar is probably the one we found in the vineyard, because its “horn” was already gone. Eventually after having gorged itself on leaves, the fifth instar crawls down to the ground and buries itself in loose soil or leaf litter where it spends the winter as a pupa. It doesn’t make a silken cocoon like many other moths but rather creates a hard case around itself. After the winter it will wiggle to the surface, break out of its case, and emerge as an adult moth. The Sphinx moth has a 3 ½ to 4 ½ inch wingspan. It is greenish gray with darker patches and pink edges and small pink eye spots. I don’t know that I’ve ever noticed one, but the pictures I found researching the insect were quite pretty.
An interesting fact about this caterpillar is that it can retract its head into its body when it is sleeping or disturbed. That’s the pose you see in the picture. It’s too bad you can’t see the picture in color because this caterpillar is a very neon orange. We all oohed and ahhed over it for a while and took pictures before we went back to harvesting grapes. I’m glad it was an orange one, because the green ones I saw in pictures really blend in with the leaves and are hard to see even though they are quite large. They can also be pink or a dark cinnamon brown color.
Although they have voracious appetites, these caterpillars are not considered a pest to the vineyard, simply because they don’t occur in large numbers. They are not considered endangered and are relatively common. Next time you’re in a vineyard or around Virginia Creeper, keep an eye out for this caterpillar!