“Teaching a child not to step on a caterpillar is as valuable to the child as it is to the caterpillar.” Bradley Millar
Caterpillars are cool. I have been fascinated by these diverse and sometimes outlandish creatures for decades and have found them to be one of the best gateways for introducing people to the wonders of nature. I have used them effectively in teaching teachers, students, and the general public in my thirty year career with state parks and the museum. Their often unusual shapes and behaviors make them instantly appealing, they are fun to raise, and almost everyone that witnesses the miracle of metamorphosis is changed in some way. Tomorrow is the annual special event at the museum, BugFest, where we get to showcase caterpillars (and lots of other types of interesting invertebrates) with thousands of visitors. Several staff plus a few volunteers like me have been out looking for caterpillars this past week to share at BugFest. We have found a good variety but I want to highlight three of my favorites.
Yellow-shouldered Slug (click on photos to enlarge)
I posted on one of the more exotic slug caterpillars last week, the Saddleback. There are more than twenty species of slug caterpillars in our region, and there are some that do not have the stinging spines of the Saddleback. The Yellow-shouldered Slug is actually one of the more mundane of the group in appearance, but I always enjoy finding any of this peculiar clan. This species apparently has stinging spines in early instars (an instar is the stage between molts), but lacks them in the final one. Slug caterpillars tend to have more instars than most caterpillars – from 7 to 9, instead of the usual 5 of most species. Not sure where this one is in the process although it is still pretty small.
The Prominents are another interesting group. Several have greatly elongated anal prolegs which resemble two tails. This Black-etched Prominent was feeding on a willow when it was discovered due to the presence of chewed leaves.
Black-etched Prominent feeding on willow leaf
They do have a remarkable camouflage that mimics the leaf color and shape, even to the detail of having a faux mid-vein-like stripe along their sides. But if pretending to be a leaf doesn’t fool a potential predator or parasite, this prominent has a couple of other defenses in its arsenal. The caterpillar can rapidly pump fluid into the two “tails” when it is agitated thereby greatly increasing their length. It quickly arches them over the body and whips the air with them which is probably especially effective against small flying parasitic wasps and flies.
Black-etched Prominent “face”
If further alarmed, the caterpillar rears back and arches its head toward the intruder, revealing markings that look like a large false head with dark eyes. It also opens and closes its mandibles in a threat display. Ultimately, this, and several other prominents, may result to chemical warfare. They can shoot an acid spray from a gland underneath the head region. I have not yet experienced this so am unsure if it deters something like a large mammal with a camera, but will let you know if and when.
Curve-lined Owlet as dead leaf mimic
Then there are the caterpillars that I have seen in David Wagner’s field guide, Caterpillar’s of Eastern North America, and wished I could see first hand because they are so beautiful or bizarre (yeah, it’s true, I do think about such things). The Curve-lined Owlet is one of those species. And then, on the same day as the encounter with the Bobcat I reported in the last post, my friend found one of these Owlets on its host plant, Greenbrier (or Catbrier, Smilax sp.). And bizarre it is.
Curve-lined Owlet on Greenbrier tendril
This caterpillar is a dead leaf mimic. It is very slow in its movements and will gently quiver from side to side when disturbed, much as a dead leaf would do in a slight breeze. The unusual elongate projections coming off the dorsal side make sense when you see the caterpillar in its environment – the tendrils of its host plant, Greenbrier, have similar curves, and the rolled edges of dying leaves are similar in color and shape. After BugFest, I will return this and a couple of the other caterpillars found down east to their rightful home (either as larvae or pupae). Every effort is made to return the larvae to the proper environment after they are used for educational purposes. Now, if I could only find that one on page 270 that mimics the color and shape of a cluster of green grapes.