This scary looking caterpillar is actually harmless — unless you’re a hickory leaf.  What a face! What horns! Such an enormous size!

Last weekend Marcy Cunkelman showed us this fifth and final instar of the hickory horned devil.

In his earlier instars he was smaller and brown and hid in the trees while feasting on hickory, white walnut, sweetgum, persimmon and sumac leaves.

In this last phase he started off green and ate voraciously.  Now he’s almost ready to pupate so he’s turning turquoise and will stop eating.  Then he’ll expel his gut(!), walk down the host plant, burrow 5-6 inches into the soil, and form a chrysalis.

He’ll emerge next June as a regal (or royal walnut) moth (Citheronia regalis), the largest moth, by mass, in the U.S.

Seven years ago Marcy documented the transformation of a similar hickory horned devil.  On Throw Back Thursday, watch a slideshow of the ‘devil’ turning into a moth in this vintage article:  Metamorphosis

(photos by Kate St. John)