Are You Sleeping? Overwintering as Adults

​It seems almost unbelievable on a frigid winter’s day, but some butterflies in central PA endure the winter as adults. The Mourning Cloak butterfly (Nymphalis antiopa) tucks itself away in crevices, underneath loose tree bark, or even in unheated buildings. For this reason, it is one of the earliest butterflies seen in the spring—and may even be seen flying during warm spells in January or February. (This allows the Mourning Cloak to be first in line at the buffet of its favorite food—tree sap—as it begins its seasonal rise.) The butterfly avoids freezing by manufacturing cryoprotectants, chemical compounds which supercool its bodily fluids and tissues.
And if you needed yet another reason to add an oak tree or two to your pollinator garden, the Mourning Cloak provides it: Oak sap is a particular favorite!
Author: Lisa Schneider
Photo credit: John Acorn