A wet warm spring has produced bumper crops of miller moths, a harmless, flying nuisance that has invaded homes and buildings around the Billings area.
But Billings is just one stop on a long journey.
The past few months provided the tender green plants the army cutworm needs to transform from caterpillar to moth. Combine them with the moths traveling the migratory path through Billings from the Great Plains and you have an influx, says Montana State University entomologist Bob Peterson.
"Those moths fly west up into the Rocky Mountains where they spend the summer," Peterson said. "Those moths spend the summer away from the heat and feeding on those alpine flowers."
While the moths are feeding in the mountains, they’re feeding grizzly bears, which eat thousands of moths per day.
Then, fattened on nectar, the surviving moths return in the fall to eastern Montana and the Great Plains where females lay their eggs for the next generation of army cutworms.
It’s this circle of life linking Great Plains moths and Rocky Mountain grizzly bears that Peterson finds fascinating.
"It connects 2 broad areas with one little insect," he said. "To me it’s amazing. I’m just floored by the life history and behavior of these moths."
What can you do to get rid of them? Not much, says Peterson, other than sweep them out with a broom or suck them up with a vacuum. They’ll eventually leave to continue the journey west.
