CATERPILLAR OF THE WEEK: Festively colored for the holiday season, The Joker (Feralia jocosa) was destined to be featured in December.
The joker has two striking forms of camouflage in its life. As a caterpillar, it blends in with the foliage of its primary food plant, Eastern hemlock. As a moth, it expertly and beautifully mimics the coloration of green lichen. Joker moths mainly fly in April and early May in the Keene, NH area, making them one of the first spring species The Caterpillar Lab has the pleasure of working with each year.
The joker’s camouflage isn’t its only changing feature—its diet preference also transforms, gradually, between its early and late larval stages. As a young caterpillar, the joker consumes mostly fresh young hemlock needles at the tips of twigs; by its final instar, it leaves the twig tips unscathed, preferring older foliage. In a poetic 1898 article describing the joker (linked at the bottom of this post), naturalist Otto Seifert stated that hatchlings preferred to dine on their hemlocks’ undeveloped pollen heads before moving on to young needles. We at TCL haven’t heard of that before, but you bet we’ll be experimenting with feeding our jokers some pollen when spring arrives!
Sometimes I really wish I could get into the heads of the naturalists who named certain species. The joker gets its common name from its species name, jocosa, which comes from the word jocose. For anyone who didn’t already know, jocose is defined as “playful or humorous.” If I were going to define a caterpillar as jocose, I’m pretty sure this species would be nowhere near the top of my list… No offense intended, my Feralia friend.
Do you see The Joker as appearing humorous in some way? If so, how? If not, what species name would you bestow on this creature if you had the honor of naming it, and why?
TCL Education Director
"Caterpillar of the Week" will highlight a different species we grow in The Caterpillar Lab each week… or, you know, at least SOME weeks. We hope you enjoy meeting the caterpillars of New England!