Fluttering around street lights and finding their way into homes across the Front Range, miller moths are back for the season.
The dusty pollinators migrate from Colorado’s Eastern Plains to the mountains every spring, stopping off along Front Range communities to sample flowers and bask in the urban glow.
All signs point to a mild-to-normal season for miller moths in metro Denver lasting just a few weeks, according to experts from Colorado State University.
Factors that influence how long miller moths stick around the urban corridor include temperatures and how many flowers are in bloom, said Lisa Mason, CSU Extension entomologist and horticulture specialist for Arapahoe County.
Last year’s cool spring and summer and plentiful blooms meant the moths stuck around for up to six weeks in some communities, but temperatures already reaching the 80s in the Denver metro will signal to the moths to move on more quickly to the cooler high-mountain elevations, Mason said.
While they’re a harmless nuisance to humans, miller moths play an important part in mountain ecosystems, said Chuck Harp, collections manager at the campus C.P. Gillette Museum of Arthropod Diversity.
“They’re a good protein source for birds, and there’s a lot of research that bears eat them at high elevations,” Harp said.
Miller moths will travel to elevations as high as 14,000 feet, sheltering under rocks until they’re uncovered by bears, marmots and pikas looking for a protein boost, Harp said.
The miller moths that survive encounters with animals, humans and cars this summer will migrate back to the Eastern Plains when mountain temperatures drop in the late summer so they can lay eggs in the grasslands.
Most people don’t notice the later migration because the number of moths is much smaller, Mason said.
In the meantime, there’s not much folks can do to prevent miller moths from entering their home other than turning off porch lights at night, Harp said.
“They’re an important pollinator and food source, and we just have to tolerate them for the two or three weeks we see them,” he said.
Denver Post reporter Lauren Penington contributed to this report.
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