Friday, October 25, 2013

The Amazing Cryopillar - Caterpillar Cryogenics

Wednesday in late October. Quiet country byway. 
First of two cold fronts pushing through central Carolina, pine straw and poplar leaves ride the chilly breeze; jackets optional, but recommended. 
Tomorrow will be colder, and Saturday morning will likely bring fall's first freeze. 
Suddenly, the lanes are alive with fuzzy crawlers! 
A quick evasive maneuver, a swift swerve left, then right; we cautiously emerge for a closer look.

A glance confirms our suspicions. Today we share the sun-warmed asphalt with dozens of America's most famous cold weather caterpillars... 
Woollybears are on the move!

Feted in October from Banner Elk, NC and Beattyville, KY in the South, to Ohio, Pennsylvania, Minnesota and beyond, the Woolly Worm is celebrated for its legendary power to predict the severity of impending winter.

Beautiful creatures, generally sporting a broad reddish-brown mid-section bordered by black on either end, the number of black segments is associated in popular lore with the number of cold weeks of winter. More black, more cold weeks. More brown, more mild weeks. Thus, the broader the brown band, the milder the winter, or so they say. 

Nabbing a couple of particularly swift and handsome crawlers for a closer look, we were surprised to find that they immediately curled their bodies tightly end to end and "played dead." No amount of pleading or coaxing could convince them to relax their posture and submit to an exam.

Only after we entirely vacated the vicinity did one brave soul uncurl and bolt for the safety of cover. Unfortunately, as soon as we swooped in again, it resumed its defensive pose. This game continued for a while before we gave up and turned to our field guides for more on the natural history of our woolly friends, larva of the Isabella tiger moth, Pyrrharctia isabella.

According to multiple sources, these amazing creatures hatch later than many other moth larvae, and often over-winter in the larval stage (as caterpillars!)These cool critters possess a natural anti-freeze (cryoprotectant) which protects their tissues from damage by the cold.
 In our region, they may simply hunker down under the insulation of leaf litter during the coldest periods of winter, then emerge to eat and complete their life cycle in a few months. In arctic regions, however, the caterpillar's bodily functions cease completely and its body actually freezes. With the spring thaw, it defrosts and resumes eating, but with such brief summers, it may require several years to mature to the point of pupating.
So as you wander the wilds of Carolina this brisk and breezy weekend, keep an eye on the ground for these crazy cryopillars. Touch them if you like, just don't be offended if they give you a cold shoulder rather than a warm and fuzzy reception.

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