Saturday, June 2, 2012

Still trying to keep up

Everything moves so incredibly fast. I see some interesting things, I take some nice pictures, I think, This could make a blog. But by then I've seen some more interesting things, taken some more interesting pictures...

Just a short time ago the Common Milkweed plants down our driveway were in full bloom. The Monarch caterpillars were chewing them up as quickly as they could, nice butterflies, like this Great Spangled Fritillary (they deserve the fancy name), were visiting them, and now already the caterpillars have gone off to make their chrysalises, and the flowers are over with.

In fact the butterfly-attracting flora has shifted to the Pickerelweed now in full bloom in our pond at the back of the yard. Lately the rather rare Dukes's Skipper has been visiting them. It normally stays in wetlands where its caterpillars feed on sedges, but the wetlands near us are now bone dry, so it's coming to us (to be sure I have to refill the pond every few days, as the surrounding trees suck it dry).

My sister came out from California for a visit, and we took her up to Crystal Bridges, which we wanted to see ourselves. The museum architecture and the painting collection were as good as everyone has been saying, but of course we made it a point to go early, a few hours before the museum opened, in order to walk the equally famous trails. They were beautifully and naturally planted. Here's a prairie section:

Best of all, the trails were alive with birds and butterflies and other interesting creatures. In a previous post I showed a picture of a tan-colored damselfly which was the female of the Springwater Dancer. On the trails here, we found the brilliantly colored male of that species. And then a little later we found another colorful insect, a day-flying moth, the Eight-spotted Forester.

But my sister, who is only politely interested in the tiny things I have been dragging home since I was big enough to walk, nevertheless found the most exciting thing of the day: an Underwing caterpillar. Underwings are a very popular group of moths. There are dozens of them, and they share these traits: The are largeish in size, they spend the day clinging to the side of treetrunks, where the cryptic coloring of their wings makes them virtually invisible against the bark. But if they want to startle an approaching predator that seems to have spotted them, they suddenly open their wings, revealing dramatically colored red or black underwings. Most of the species are very similar to each other, differing in only fine details of pattern, and part of the fun is trying to sort out what species you are looking at. Here's a picture I took of one last year (it's a live moth, by the way; that gray thing on its back, whatever it is, is not a pin).

Well, we're very fond of caterpillars, photographing them, sometimes raising them (we have a Picasa Web Album of them, but we had never managed to find an Underwing caterpillar (they are even more cryptically colored than the adult moths). And now my sister had found one that we had both overlooked. This picture of it will show you how cryptic they are:

Now some of my readers may wonder what all the fuss is about, over a little gray wormy thing, but that is because they have not yet discovered the wonder of caterpillars. Caterpillars are at the base of almost every food chain you can imagine. Surely half of all insects, high percentages of birds, are designed to feed on caterpillars. Caterpillars, not wanting to be consumed, have over the millions of years devised incredible stratagems to avoid being consumed, and their predators have devised more stratagems to be able to find and eat them, to which the caterpillars have responded by devising even more incredible stratagems. Browse my album and you will come away loving caterpillars, as every enlightened person should.

Even as I write this we are gearing up for the caterpillar season. Butterfly and moth caterpillars are often very specific in the plants they will feed on, Monarchs, for example, only feeding on plants in the milkweed family. We try to plant at least one new plant each year that some particular caterpillar feeds on. A few years ago, for instance, we started a Pipevine (Aristolochia) in our backyard, which is the food plant of the Pipevine Swallowtail butterfly. Aristolochia, itself not wanting to be eaten, produces a powerful poison, which protects it from most things. But the Pipevine Swallowtail caterpillar has learned to sequester that poison in its own body, so that it becomes poisonous to things that would eat it. To make sure that every bird or lizard that might eat it knows in advance that it is poisonous, and so will leave it alone, it manages to look poisonous. Here's a picture of the ones we found on our pipevine plant.

Sphinx moths, the ones that hover in front of flowers like humming birds (many are nearly the size of humming birds) while they use their long tongues to drink the nectar, have caterpillars called "horn worms" because of the long spine at the end of their bodies. Cheryl, with her sharp eyes, spotted a Waved Sphinx hornworm in our ash tree. We love to raise these finger-sized caterpillars into adults, so we brought it in and set it up in an aquarium and fed it ash leaves by the dozen, which disappeared faster than we would have imagined. The caterpillar got bigger and bigger, then one morning was gone. We had filled the aquarium several inches deep with loose soil and leaf litter, and it had buried itself to form its pupa. Here is the handsome caterpillar we had; if all goes well, later we will show a picture of the moth it becomes.

But so far the most interesting caterpillar we have is one I picked up off the ground looking like it was dead. A number of hunting wasps feed their young on caterpillars. The adult wasps feed on nectar themselves, but their larvae are carnivorous. These wasps find a caterpillar, flip it over on its back, sting the nerve centers of each segment, then bury the paralyzed caterpillar underground and lay an egg on it. The caterpillar being alive stays fresh and juicy for the larva, and the larva carefully eats non-vital tissues first, to keep it fresh as long as possible. When the caterpillar is consumed, the larval wasp makes its cocoon, then emerges as a wasp and takes up the family business. What happens is, sometimes something disturbs the wasp, and it drops the caterpillar it is carrying. I found one of these, lying comatose on the ground, and brought it home to try to identify it. It looked to me in fact like an Underwing caterpillar, and I got out all my books, but I could not identify it further. For two or three days it lay on my desk, staying fresh and round, not drying out like a dead thing.

Then one day I stepped into my study, looked at it, and it had started moving slightly. I had heard of this happening before. If the larval wasp did not begin eating it at once, it would eventually recover from the paralysis of the sting. Now I really needed to identify it. If it recovered fully, it would need to eat, and if I didn't have the proper identity for it, I would not know what specific food it needed to have. So I took pictures of it and sent them to BugGuide, asking for a quick identification, and explaining my urgency. Here are some pictures of it.

Within hours the caterpillar expert (who signs his name shotguneddie) reported to me that it was the caterpillar of the Lunate Zale, not an Underwing, but a closely related species, and suggested I feed it blackberry leaves. We made a container for it and loaded it with blackberry leaves. For several days we could see that it was beginning to wander, but it was not feeding, and we thought perhaps it would not recover enough to begin normal life. Then one day we found fresh droppings in the container, and the leaves began disappearing. Here is a picture of it today. If it goes on to make a cocoon, and finally emerge as a moth, we will report on it.

No comments:

Post a Comment