Annual Miller Moth Migration from the Denver Post

The annual migration of miller moths from the Eastern Plains to the mountains is in full swing, confounding house cats and annoying humans trying to enjoy warm evenings outdoors.

Photo courtesy CSU

But this, too, shall pass — very quickly this time around. Entomologists say cold weather, with little snow cover to insulate soil on the plains, killed larvae and cut the population of the fluttering pests compared with years past.
"It's not going to be a year for the ages or anything," said Whitney Cranshaw, a professor and extension specialist in entomology at Colorado State University. "That's not to say there won't be problems, but it's not going to be an epic year."

Read more: Pesky Miller moths back — but not as many as in years past - The Denver Post http://www.denverpost.com/news/ci_18195880#ixzz1OLHwMtJS
Read The Denver Post's Terms of Use of its content: http://www.denverpost.com/termsofuse

Here's also a CSU Fact Sheet about the moths!

Millers on a Garden Hose:  CSU