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Keywords: moths, insects, moth biodiversity, New England moth inventory |
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For the second year in a row, a Carolina wren has nested in the hanging geranium pot outside our front door. Its mottled eggs lie within a domed nest of grass, safely hidden by the foliage of the geranium. On the other side of our front door is an equally if not more exciting feature --our porch light. The light itself is nothing special, the usual 60-watt fixture, but the creatures that it attracts night after night all season long is what makes it so exciting.
Come dusk, the nocturnal inhabitants of our forests and fields begin to stir. Some of them seem incapable of resisting the gravitational pull of our porch light. Moths, beetles, flies, and many other creatures swarm to this beacon in the night. They flutter about the light, performing what seems like some pagan dance in celebration of its brilliance. Others come to rest upon the side of the house to stare at the light as if in some hypnotic trance. Still others fly to it and quickly retreat back to the darkness, as if they somehow feel too vulnerable.
Sometimes I feel guilty for holding insects hostage by porch light and keeping them from their normal nocturnal activities. These are not weary travelers that we are attracting, but creatures bent on a mission of mastication and procreation, with very little time for either. They come to the light in the evening because they mistake it for the moon. For millions of years, these creatures have used the moon to navigate the night skies, using it as a reference point to keep their flight straight until they detect the chemical fragrance of a female and switch gears to follow that reference. Often, only the males are attracted to lights, so they are the ones that are held hostage, having to endure a night of celibacy. They will escape their bondage only on the slim chance that they will pick up the scent of a female, or if we extinguish the light.
Variety in Color and HabitHundreds of moths visit porch lights over the course of the seasons, from the giant silk moths, such as the Luna (Actias luna) and Cecropia (Hyalophora cecropia), to the inchworm moths such as the Sulfur (Hesperumiac sulphuraria) and Angle moths (genus Semiothisa). We also see the boldly patterned Tulip Tree Beauty (Epimecis hartaria) with alternating bands of blacks, whites, and browns, and the stunning Green Marvel (Agriopodes fallax) 
with florescent green and black markings. The Sphinx moths (family Sphingidae) have cryptically patterned forewings that hide them from most predators by day, but if disturbed, some species flash their hind wings, exposing large eyespots to frighten and discourage predators. The beautiful Underwing moths (genus Catocala) have brightly colored hindwings that earn them their name. The purpose of their brightly patterned underwings is the same as some of the Sphinx moths, to startle and discourage predators from dining on them. Sometimes this quick flash of color startles a predator enough to give the moth a fraction of a second’s time to make a quick getaway. The predator, in pursuit, follows the brightly colored or patterned hindwings, but loses the moth as soon as it lands, when it covers its hindwings with its forewings and disappears into the background.
Against the white backdrop of our house, the patterns on these moths show nothing of their camouflage abilities. Dressed in their drab blacks, whites, grays, greens, and browns, the moths literally disappear against the trunk of a tree, a lichen covered rock, or the leaf litter on the forest floor. Some moths that emerge as adults in the fall, such as the Maple Spanworm Moth (Ennomos magnaria) mimic the colors of the changing foliage to better camouflage themselves from predators. Other moths, such as the Bird Dropping moths, (Noctuid family) mimic, surprisingly enough, bird turds. These moths employ an infinite variety of poop disguises to discourage predators from consuming them. The Beautiful Wood-Nymph (Eudryas grata) has iridescent speckled blues on its body that react to sunlight, giving the impression that it is a fresh dropping.
Conversely, other moths don’t bother to hide at all, but advertise their presence in brilliant warning colors of red, yellow, and orange instead, such as the Virgin Tiger moth, (Grammia virgo). In the natural world, bright colors often signify that an organism is poisonous or distasteful, thus steering potential predators away. Moths that choose to operate by day often mimic other insects, specifically stinging insects, in order to help dissuade predators. The Hornet Clearwing (Paranthrene simulans) is a perfect example; it not only displays the markings of a hornet but also adopts a posture of stinging if threatened. Another daytime moth, the Hummingbird Clearwing (Hemaris thysbe), mimics the hummingbird as it hovers above nectar-rich flower heads.
How do moths get their common names? Many moths are named for the food the larvae, or caterpillar, feeds on, such as the Chickweed Geometer (Haematopis grataria), the Linden Prominent (Ellida caniplaga), and the Blackberry Looper moth (Chlorochlamys chloroleucaria). Other common names describe what the larvae do to their host plants: the Birch Skeletonizer (Bucculatrix canadensisella), the Redbud Leaffolder (Fascista cercerisella), and the Goldenrod Gall moth (Gnorimoschema gallaesolidaginis). Other names point out distinguishing characteristics of larvae or adults, such as the Rose Hooktip (Oreta rosea) whose wing edges resemble the dead, drying leaf on which it often rests during the day, and the Harris’ Three Spot (Harrisimemna trisignata) with three distinct spots on each of its forewings.
The Underwing moths have interesting common names that refer to human relationships such as the Girlfriend, Married, and Widowed underwing. There is the One-Liner, the Mother, Sweetheart, Once-married, Youthful, Bride, Consort, Old Maid, Old Wife, Little Wife, and the Betrothed underwing. Others are called the Little Nymph, the Sordid, and the Cunnubial underwing. Some names reflect the emotions that accompany relationships, such as Inconsolable, Dejected, Sad, and Mourning underwings as well as Wonderful, Charming, Sweet, and Graceful underwings. Finally, one “chief” species has a name that may be used to sum up the whole underwing world: Catocala clintoni, otherwise known as the Clinton underwing.
Moths know nothing of the names we give them; their signatures are written on the wind in the form of chemical fragrances – or pheromones -- sent out to tempt and lure potential mates to their sides. Because moths operate by night, the visual clues employed by their cousins, the butterflies, are useless. Flying by day, butterflies advertise themselves in brilliant colors both to attract a mate and ward off potential predators. They fly throughout our fields and forests seemingly oblivious to the dangers all around them. Moths, on the other hand, employ an arsenal of chemical pheromones to communicate with each other. They can cover a much farther distance to get their message across than any butterfly dancing in a field. The female moths will often fan the perfume with their wings while they remain stationary on a tree or the ground until a suitable mate comes along. Most folks become familiar with the bright, diurnal butterflies and generally ignore the subtle, nocturnal moths.
Whether butterflies and moths operate by day or night, there is always danger lurking around every bend. At night, the porch light also attracts many predators. In the evening, all types of spiders can be seen jockeying for position around the light. There are orb weavers like the Garden spider (Araneus diadematus) and the Black and Yellow Argiope (Argiope aurantia). There are Cobweb, Sheetweb, and Funnel web spiders as well as Jumping, Crab, and Wolf spiders. One of the most common is the Daddy-Long-Leg spider (family Phocidae) whose long legs cast ominous shadows across their intended victims. Predatory beetles and wasps hunt at the light, along with plenty of scavengers looking for any morsels of food left behind. The American toad (Bufo americanus) is a regular visitor beneath the light as are the masked and short-tailed shrews that scurry out from the fissures in the rocks to grab a meal. Bats are numerous overhead and often dive bomb around the light to grab moths in flight.
On the ground beneath the porch light lie the littered remains of moth wings and beetle bodies, the physical evidence left behind from the previous night’s carnage, but the feast is not yet over. Chickadees, titmice and the ever-present Carolina wren continue the carnage as daylight spreads over the landscape. They bang against the house in pursuit of prey, desperate to feed their growing young. Chipmunks rummage through the leaf litter around the light to catch and consume any creature trying to hide there.
I venture out as early as possible to catch in jars any new moths not yet observed under our light. I do not kill them -- mine is a catch and release program -- but the stress of having lived through a night of spiders and a morning of birds is probably more than most moths can take. I identify them and release them within 24 hours so that they can continue their nocturnal wanderings. In three years of collecting and identifying, I have identified approximately 250 species successfully. (Click here to view the moth inventory list) I’m confident that I could multiply that number by four to reach the number of species that I haven’t been able to identify. Some moths, the micro moths, can only be identified by microscopically looking at their genitalia, which goes well beyond my desire to know.
Moths are excellent examples of the success in leading a nocturnal lifestyle. Ninety-five percent of the 12,000+ North American species of Lepidopterans, (butterflies and moths) are moths. These often overlooked representatives of the Lepidopteran world can be viewed nearly every evening during every month of the entire year without expending any more energy than it takes to switch on a light. And remember, you don’t have to venture any farther than your own porch light to enjoy these wonderful and beautiful creatures.
Covell, Charles M. 1984. A Field Guide to the Moths of Eastern North America: The Peterson Field Guide Series. Houghton Miflin Co. [Out of print]
Mitchell, Robert T., Andrew Durenceau, Herbert Zim, and Andre Durenceau. Butterflies and Moths: A Guide to the More Common American Species (Golden Guide) St. Martins Press.
All photographs copyright Richard Wolniewicz
The views and opinions expressed in all articles that appear in "Conservation Perspectives" are those of the authors and do not necessarily reflect those of NESCB.