PUBLISHED: May 18, 2023 at 1:24 p.m. | UPDATED: May 18, 2023 at 5:17 p.m.
Once reviled widely as a nuisance, the millions of miller moths migrating through cities along Colorado’s Front Range this week increasingly are seen as an ecological necessity.
These native moths matter more than ever, entomologists say, because other pollinators, such as bees, are decreasing — which imperils native vegetation and potentially billions of dollars worth of agricultural food crops.
The miller moths (Euxoa auxiliaris) come from Army cutworms, which turn into adult moths on the Eastern Plains before swarming into metro Denver and other urban areas. If not distracted by household and commercial light, each moth typically flies up to 100 miles, moving on into mountain foothills before July.
They’re crucial food for birds, arriving just as newly-hatched chicks need protein. They become a major food source for bears foraging after emerging, hungry, from hibernation. And fuzzy moth bodies pick up and carry pollen from one flower to another, helping native plants survive.
“Pollinators as a whole are trending toward declines, so we should learn how to share our space and welcome miller moths as they pass through,” said Shiran Hershcovich, a manager at the Colorado Butterfly Pavilion, an insect research hub. “Be mindful of your light pollution levels and turn off all unnecessary lights this spring.”
But, in recent years, a different kind of moth — a non-native invader — has been complicating the spring scene and intensifying the buffeting of people inside warm and robustly-lit homes. This European Large Yellow Underwing (Noctua pronuba) comes from caterpillar worms that favor non-native turf lawns and can hang around longer than the native miller moths.