Miller Moths

Living along the Front Range means that every spring we experience a small, dusty migration. Those of you who have been here a while know exactly what I’m talking about. Those of you who are newer to the area: meet the miller moth. Miller moth, as it turns out, is a term used to describe any moth commonly found in homes, but the one we see every spring is the adult stage of the army cutworm. These moths migrate from the plains to the mountains every spring, filling windows and lampshades with their dusty little wings in Colorado and neighboring Rocky Mountain states. As adults these crazy critters feed on nectar, NOT your wool sweaters (that’s a different type of miller moth) and also do not lay eggs while migrating. So be kind to the dust butterflies as they move through your home and help them escape If you can. They’re only passing through, looking to get out of your lampshade and into a mountain flower patch.

Fun Facts about miller moths:

  • Miller moths start as a caterpillar in late winter and early spring
  • During their late spring migration, some moths travel hundreds of miles from neighboring plains states
  • Miller moths migrate back to lower elevations in the fall, but in such fewer numbers that we rarely notice
  • Predators of the miller moth include bears, who can eat thousands of them at a time
  • Swallows and other birds may concentrate at intersections to feast on moths leaving stopped cars
  • Insecticides are not particularly effective against miller moths, since the moths themselves resist it rather well and will do nothing to prevent more moths arriving in the area

For more information see this fact sheet from Colorado State University:

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