Hornworms or hummers?

Aug 15

My wife and I have devoted a lot of effort to providing plants for wildlife to utilize for food and shelter. I greatly prefer to have a plant provide nectar for hummingbirds than to put out a feeder with sugar water. Coral or trumpet honeysuckle (Lonicera sempervirens) is a native species that provides a beautiful red flower with abundant nectar for hummingbirds (see photo above). This seems to be an unequivocal win for the garden since it is beautiful, hardy, and highly attractive to hummingbirds. But today I discovered the "rest of the story" as it pertains to the biology of this wonderful honeysuckle.

As I sat rocking on our porch without a care in the world, I suddenly noticed something troubling- there were bare spots on our two honeysuckle vines and tell-tale small dark pellets on the ground underneath. The pellets seemed to be "frass" or caterpillar poop and this indicated something was eating our valuable vines! A quick search and about 10 minutes picking produced the haul shown in the photograph of a group of caterpillars, mostly green but a few brown. A close-up of one of the more common green ones (see photo below right) indicated that this was clearly a hornworm with a terminal harmless spine. I checked this out in the "bible" of caterpillar identification (Wagner's "Caterpillars of Eastern North America") and found a match with the snowberry clearwing sphinx moth. This moth in fact resembles a hummingbird in its flight characteristics and feeding on nectar, but mimics a bumblebee as a means of protection from avian predators.

So here I had a conundrum- some very interesting caterpillars of a species that I value were competing with both hummingbirds and their own adult stage by eating the plant that produces their nectar. My solution for the moment is to pick off all the caterpillars that I can find (far from an easy chore since they are VERY well camouflaged- green and subtly counter-shaded to blend in extremely well with the foliage) and put them in a container where I will feed them on less valuable honeysuckles until they get ready to pupate, when I will release them.

So what have we learned- that once again Nature is more complex than our simple mindsets, and that manipulation of plants for our purposes is often diverted to other ends? This provides an education for us to remain open to new ideas and to value this complexity and not to find it frustrating. Indeed it is exciting that the unexpected can break out and astound us- we have only to be observant and find wonder in the events as they unfold. I also learned that I can sometimes learn more while rocking on the porch and contemplating Nature from that perspective than hiking in the woods and fields!