Friday, June 6, 2008
Copper Underwing Caterpillar
The largest family of lepidoptera is the Noctuidae (from the Latin noctua meaning owl) with more than 35,000 species worldwide. The family is known as the owlet moths. The adult moths are nocturnal, like owls, but you can find them at night despite their camouflage because of the bright reflection of light from their eyes when you scan a tree trunk with a flashlight.
Underwing moths are part of this large family and are named because of the bright color or striking patterns on their hind wings. The colors are hidden by the drab forewings when the moth is at rest but are very conspicuous in flight. The caterpillars of many owlet moths are farm and garden pests – like cutworms and army worms. Today’s topic, the Copper Underwing, is not in that notorious company. I found it on top of some fallen dried pine needles in my backyard on May 31. It had probably dropped from the highbush blueberry shrubs just above it.
Name. The Copper Underwing is Amphipyra pyramidoides. The adult moth has shiny copper-colored hind wings or underwings, so it seems that the genus name made up of amphi meaning “on both sides” and pyr meaning “fire” is a description of the moth in flight. The suffix –oides on the species name means “resembling” or “similar to,” and it quite likely refers to the strange-shaped hind end of the caterpillar.
Identification. The caterpillar is bluish-green with lots of pale yellow spots and thin yellow and white stripes along each side. The stripes run all the way around the hind end and connect with the stripes on the other side. The most conspicuous feature though is the very prominent hump, which looks like a pyramid, on the eighth abdominal segment. The ninth and tenth segments are relatively small so at first glance it looks like the pyramid is on the last segment.
Life cycle. The Copper Underwing moth lays its eggs from September into November. There is one brood per year. The eggs hatch in the spring when there are leaves to eat. The caterpillars feed on a long list of different woody plants including maple and oak, but also apple, cherry, blueberry, walnut and rhododendrons.
Department of Defense. The Copper Underwing has two approaches to avoid being eaten – one used by the caterpillar and the other by the adult moth. The caterpillar does not stay long at its table after eating. It moves away to a fresh spot, thereby escaping certain birds which use leaf damage to indicate location of prey. The adult moth, like other owlets, has specially developed tympanic organs somewhat like ears which it uses to pick up sonar signals from bats and take evasive action. It can not only determine how close or far the bat is but also the direction it is coming from.
Sources. Caterpillars of Eastern North America by David L. Wagner (I highly recommend this book for anyone interested in caterpillars. It has several hundred excellent color photographs and for most species there is also a photo of the adult moth or butterfly.); Discovering Moths, Nighttime Jewels in Your Own Backyard by John Himmelman; Insects: Their Natural History and Diversity by Stephen A. Marshall. ∆
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