For the Birds Radio Program: Luna Moths on Burntside Lake
Last week, when I was teaching an Elderhostel on Burntside Lake, we found two luna moths resting on a cabin, and a little girl brought me another one she found on some steps. Despite our waving it up and down, it didn’t take wing, and when I set it on a fern, it didn’t even cling lethargically—it dropped limply to the ground beneath. We decided to let it die in peace and then give it to a school for display. A nighthawk would have loved to eat it, but once you’ve looked into a luna moth’s eyes, it’s impossible to feed it to even your favorite insectivorous bird.
Luna moths are among the most beautiful of all creatures, with huge, luscious green wings, delicate markings, intelligent eyes and feathered antennae, but the one useful thing they’re missing is any mouthparts at all. The moment they emerge from their cocoon, their days are numbered. They must find a mate and reproduce on the energy they still have stored from caterpillar days. The trick is to do what they must before a predator, or a person with a butterfly collection, can find them, and before their energy ebbs away.
I put the fragile creature on my table to admire while I wrote. It rested for a couple of hours, and then suddenly its wings started quivering. I thought it was in its death throes, but then figured out that it was working up its metabolism in order to fly away. When I set it on an outside stump, it quavered its wings a minute or two, and then flew away as quickly yet delicately as an angel. As with the other luna moths we saw, there was at least some hope that it found a mate and appropriate plants for its eggs.
When we moved to Duluth in 1981, moths by the dozens, from huge cecropias to tiny unidentifiable ones, collected on our window screens on June evenings. We slept to cricket music. June bugs crawled on the sidewalks and crunched under baby coach wheels.
Now, with quality bugs so much harder to find, the birds that depend on them for sustenance have vanished. The Tree Swallows in the neighborhood disappeared years ago. The flood of martins and swallows coursing overhead in May and August migrations have dwindled to a trickle. I used to sit out on the porch in early summer and listen to nighthawks and occasionally even Whip-poor-wills yelling of a June evening, but I haven’t heard them from my backyard in years.
Where did they go? Birds cannot live without food, and just about everything we humans do destroys their food. Lawn care companies apply herbicides and insecticides on lawns. These insecticides kill earthworms as well as insects, explaining why we have a fifth as many robins in my neighborhood as we did fifteen years ago. County and state highway departments apply roadside herbicides to maintain wide shoulders. Why should we pay the taxes necessary to chop down plants when it’s cheaper to poison them?
We run over insects and birds with our cars. I’ve never figured out how to avoid a tiger swallowtail when I’m cruising at 55 mph. By the time I can actually see it, it’s too late to brake or swerve. We add insecticides to ponds and lakes to eradicate mosquitoes without considering that wearing a net on the worst days may be a little smarter than poisoning the water that we, too, depend upon. We zap any moth survivors with bug lights. We’ve made our world inhospitable to all but the most generalized omnivores. The increase in crows, gulls, foxes, and raccoons in Duluth represents a loss of biomass in other, more specialized and more delicate species.
My little luna mother has survived despite these difficulties. I hope she hung in there long enough to keep her species going at least a little longer.