Nettle-eating caterpillars

It's been a whirlwind the past few days. I left Columbus at 1:00 am last Friday morning, and drove about seven hours due east, to Millersville, Pennsylvania. Destination: Millersville University, home of the Native Plants in the Landscape Conference. This was its 20th year, and my fourth time to visit. The event draws upwards of 300 people every year, and always sports an interesting slate of speakers, and a gymnasium packed with native plant vendors. I was there to give the Friday night keynote, and then another breakout session talk the following morning.

The reason for my early morning departure was this guy, Dr. David Wagner of the University of Connecticut. Dave was giving the Friday morning keynote, and I really wanted to hear his talk. Wagner is the foremost expert on caterpillars, and has published two ground-breaking books on lepidopteran larvae, which can be found HERE and HERE. These books are fascinating windows into the world of some of our most interesting and beautiful insects, and I highly recommend them.

On Friday afternoon, escorted by botanist Tim Draude, we were able to visit a nearby park and look for bugs. As might be expected, we found many, including some very cool insects, and I made many photos. In the picture above, your narrator (left) and Dave Wagner stand by one of our more maligned native plants, which scarcely shows up as most of its foliage has been eaten away. If you look closely to the right of Dave's collecting sheet, you'll notice numerous little tubular squiggles on the plant stems.

Here's a closer view of the plant in question, which is tall nettle, Urtica dioica ssp. gracilis (grrr, I dislike plant varieties being labeled as subspecies). Tall nettle is just that, and these luxuriant plants towered to five feet or so in height. There were scores of the nettles throughout the park, and all of them were densely colonized by these caterpillars, which should show up a bit better in this shot.

And here's one of the nettle-feasters up close and personal. It's rather dark and plain, although some of the older specimens were prominently slashed with creamy-white stripes, and all of them were beset with columns of spines. If you can evolve your way into it, it is probably rather advantageous to have a diet of stinging nettle if you are a caterpillar. And this plant surely can put the hurt on us mammals. Swipe your hand through a stand of it and you'll learn quickly about the wonders of urticaceous hairs. These hairs are hollow and full of chemical irritants. When contacted, the brittle hair tip snaps off leaving a sharp point that jabs whatever brushed it, and in go the itch-producing compounds.

Most animals, us included, quickly learn to avoid nettles, and the plants' toxicity probably affords these caterpillars some degree of protection against predators.

Those nettle-eating caterpillars - at least those that survive - will morph into this gorgeous butterfly, the red admiral, Vanessa atalanta. That's right, weedy nasty stinging nettles are the host plants for this stunning insect. Much of not all of the eastern U.S. experienced enormous numbers of red admirals; an invasion the likes of which has seldom been seen before. I wrote about this phenomenon HERE.

Nettles may be much despised by people, but nearly all of them that are found in these parts are native species, and clearly contribute to the production of animals that we enjoy.

If you want to learn a lot more about native plants, their relationships with animals, including caterpillars, attend the Midwest Native Plant Conference! It is held in Dayton, Ohio, and the dates are July 27, 28, & 29. David Wagner is one of the speakers, and there'll be field trips and opportunities to see caterpillars, plants, and much more in the field. All of the details are RIGHT HERE.