A subcommittee of the Hanover Conservation Commission
THERE'S A BUTTERFLY NEAR YOU, EVEN IN THE DARKEST DAYS
Dear Hanover Readers: This interesting note on over-wintering wildlife is shared with us by Kent McFarland and the Vermont Center for Ecostudies (VCE). Please enjoy, and keep an eye out in your neighborhood.
Mourning Cloak gathering sun after a long winter. / © K.P. McFarland
Mourning Cloak butterflies are one of the earliest to appear flying about in spring. They spent the fall fluttering about feeding and storing abdominal fat. Before winter arrived, they found a space to hide – in the woodpile, a hollow tree, a crack in a rock, or inside an old shed.
In these protected and somewhat insulated hideouts they enter diapause, a state of dormancy. They become sluggish as the temperature drops. The freezing point of their cell tissue is lowered by an increased content of sugars, which act as an antifreeze. Mourning Cloaks produce sorbitol, a sugar alcohol obtained by the reduction of glucose.
Sorbitol is also a sugar substitute that is often used in diet foods and it can also be found in plants in the genus Sorbus, represented by Mountain Ash in New England. Using electrical conductivity, biologists in Alaska found that Mourning Cloaks do not freeze until the temperature reaches -22 F, something that their cozy hideout should never experience.
Click here to learn more about over-wintering butterflies on the VCE Blog.