Anyone living in Eastern Colorado will tell you the miller moth is the bane of their existence. From one year to the next, one can never guess if their home will be invaded by this invasive flying object. Because of this, the biannual migration is often reported in the news, and the Colorado State University Cooperative Extension (CSUCE) posts an annual prediction. Colorado isn’t the only state to be annoyed by the miller moth. Parts of Wyoming, Nebraska, Kansas, and Oklahoma also see them, although not nearly as much as residents of Eastern Colorado.
What is a miller moth, you ask? That was the question I asked my first summer in Colorado springs. For the entire month of May and into June, I was dodging flying objects, especially if a light was on. I had to walk out of the bathroom to brush my teeth as they flitted about the lights. When I turned out the light to sleep, there would be at least a dozen on the ceiling. Luckily, none flew into my mouth as I slept. They travel at night and were not doubt trying to find a way outside.
Miller moth is the name given to the army cutworm. Eggs are laid in the plains. About late spring, they transform into moths and migrate to higher elevations for the summer. In late summer and early fall they again migrate to the plains where they multiply. If they live that long. Many don’t survive the migration either way as they are routinely squished or sucked into a vacuum cleaner (a popular remedy) if they find themselves inside someone’s abode. Besides having to dodge airborne miller moths, when they land they, leave behind a reddish-brown substance. “This is called meconia and is the waste product stored during pupal development.” It is a sign that a moth recently “emerged from the pupa.”
The miller moth got its name because of the scales on the wings. When they shed, “[t]hese scales reminded people of the dusty flour that cover the clothing of one that mills grain.” They are called army cutworms because they tend to travel in “army-like bands.” It is not uncommon to see them moving across roads. The word cutworm is a bit of a misnomer as it is actually a caterpillar. It’s possible it is called a worm because it burrows underground as it pupates.
The flight path of the miller moth is partly determined by the weather. The years 2001 and 2002 were particularly dry so there were not a lot of flowers to feed on. In contrast, the winter of 2006 as well as the early spring of 2007 were quite wet. The result being plenty of flowers to feed on. Also contributing is the people population. The miller moth travels at night and uses the moon as a navigational aid. House lights confuse them. At sunrise, they look for a dark place to hide, often dark doorways. A door is opened, they are disturbed, inside they fly.
To minimize infiltration, the CSUCE suggests residents “seal any obvious openings, particularly around windows and doors…reduce lighting at night in and around the home during flights” including “turning off all unnecessary lights or substituting non-attractive yellow lights.” The CSUCE also recommends removing moth carcasses as they may attract other vermin.
Colorado State University Cooperative Extension. May 9, 2007. Questions and Answers About Miller Moths. Retrieved from http://www.ext.colostate.edu/pubs/insect/tips-millers.html on June 2, 2007.