Coordinator notes: Oeneis chryxus and Oeneis calais are considered by some to be separate species. O. chryxus in general fly at lower altitudes and in even-number years. It is rarely seen in odd-number years (as is 2011). O. calais fly at higher altitude and in both even or odd number years. There are ways to tell the two apart but specimens are necessary. We are still accumulating data regarding the distribution of both of these arctics in Colorado and the Rocky Mountains (see Scott, 2006 - Papilio #12, New Series (privately published journal, 2006).