Little Critters Cope with Winter

Winters in Wyoming are long and harsh. But even during mid-winter, there can be a warm day

with the sun shining and little wind. The Angle Wing Butterfly (Polygonia faunus hylas)

overwinters as an adult butterfly. When it is not hibernating it may come out and fly even

when snow is on the ground. The caterpillar feeds during the short summer months.

Angle Wing Butterfly Photo by John Nordin, 14 September 2008, Green Rock picnic ground west of

Laramie, elevation 9800 ft. The 1.5 inch-sized butterfly spreads its wings in the sunlight while feeding on

sap oozing from a pine tree on a chilly morning.

The Chryxus Arctic (Oeneis chryxus) takes two years to complete its life cycle. The butterfly

overwinters as a caterpillar during two winters, eventually pupating and emerging as an adult

butterfly during the second year. The caterpillar produces a special antifreeze to keep ice

crystals from forming within its body during the winter, where temperatures can drop to less

than -40oF at 10000 foot elevation where it lives.

Chryxus photo by John Nordin, 20 July 2008, Snowy Range Pass, Elevation 10800 feet. Butterfly about

the size of a half-dollar.