Friday, November 13, 2009
Nancy Teasdale of Heald Road found this caterpillar in mid-September at her back door. It interested her for a number of reasons. First, it was large and, as she described it, “quite startling and reminiscent of the banana slugs in Washington state.” Second, she thought it was late in the season for a caterpillar to be out and about. Third, she thought it was a beauty and something worth sharing with others. I agree it’s a beauty. I have only seen one myself and found it imposing and memorable.
Name: This caterpillar is the larva of the Pandorus Sphinx moth, Eumorpha pandorus. Sphinx moths are so-named because of the sphinx-like position the larva adopts when alarmed. Sphinx moth caterpillars as a group are commonly referred to as hornworms because they typically have a short horn on their rear end – like the familiar tomato hornworm which is the larva of a sphinx moth.
The genus name, Eumorpha, is made up from the Greek “eu” meaning good and “morph” meaning form or shape. Other sphinx moths, of which there are about 70 species in eastern North America, probably don’t see it as good form that Pandorus took this name. To rub salt in the wound, the species name pandorus comes from “pan” meaning all and “dora” meaning giving – as in Pandora of the famous box. So, this is an all-giving moth of good form.
Form and shape: I wouldn’t argue with good. I would add that the larvae reach 3 1/2 inches long and are as thick as your finger before going underground and pupating, They vary in color with green, orange, pink and brown forms all possible. They have large white or yellow spots surrounding the spiracles (breathing holes) on five of the abdominal segments, and a peppering of tiny, black dots. When alarmed, Pandorus retracts its head and first two thoracic segments back inside the third thoracic segment. In this state, the caterpillar has a squared-off front end and in profile, you can’t see the head at all.
Unlike other species of hornworms, Nancy’s caterpillar did not have the typical hornworm horn on its rear end (eighth abdominal segment). Instead, it had the eye-spot characteristic of this species. Before the caterpillar’s final molt, that segment bears a peculiar horn which is long and thin and partially coiled back over the body. (Check the photos on www.bugguide.net.) In the final molt, the horn is replaced with the eye-spot or “‘button.”
Life style: Nancy’s caterpillar was probably looking for a place to pupate. It would burrow into the ground and make a smooth-skinned brown pupa without a cocoon and would spend the winter in that state. Sometime around June, the pupa will wiggle its way to the surface and then emerge as the adult Pandorus Sphinx moth. As you might expect from such a large caterpillar, the moth is also large with a wing span of three-and-a-half to four-and-a-half inches. It is light brown and olive green with some pink marks on the forewings. The adult moths feed on flower nectar. They are known to visit petunias, bouncing bet and white campion. The caterpillars feed on the leaves of grapes, Virginia creeper and Ampelopsis. You may come across a pupa when doing clean-up in the garden this fall or next spring. Tuck it back in.
Sources: Borror and DeLong’s Introduction to the Study of Insects; Caterpillars of Eastern North America, David L. Wagner; Insects, Their Natural History and Diversity, Stephen A. Marshall; Giant Moths of Prince Edward Island at www.silkmoths.bizland.com/epandoru.htm; and, of course, my favorite insect site www.bugguide.net (search for Pandorus – there are photos of the caterpillar with the curly horn.) ∆
What are you finding?
If you find something living or growing in your yard or on one of your walks in the woods and you think it might be interesting or you are just curious about it, drop me a note at firstname.lastname@example.org ∆
© 2009 The Carlisle Mosquito