Monday, June 4, 2012

Some ordinary but extraordinary caterpillars

I am infatuated with caterpillars. The more that I learn about them, the more I realize just how vital butterfly and especially moth larvae are to the natural world. Without them, we'd lose most of our songbirds, plant communities would fall into collapse, and many of the things that we - Homo sapiens - use and need would be lost.

Besides all of that, they're just plain cool. Tubular works of art, in many cases.

Expert photographer Jack Hoying sent along some incredible shots recently, and gave me permission to share them. We'll get to Jack's stuff soon, but first a few cat shots of my own, from recent excursions.

I engaged in a brief botanical expedition this morning with botanists Dan Boone, Andrew Lane Gibson, and Brian Riley. Part of the trek meant bushwhacking through a thickly overgrown meadow. I was pleased to glance down at one point, and see that I had picked up a hitchhiker. This gorgeous caterpillar, Cucullia asteroides, which goes by the curious common name "the asteroid", was riding along on my leg.

Not one to let a photo op pass by, I placed the asteroid on some plants more friendly to its tastes than Levi's denim, and snapped a few images. This is a large colorful animal that feeds primarily on goldenrods, asters, and perhaps other members of the composite family.

While up in northern Michigan leading my NettieBay Lodge expeditions a week or so ago, we had stopped at a quiet pine-filled campground one day for lunch. A few of our party were sitting at the base of a red pine when they heard a soft thud, and looked down to see this interesting caterpillar. It had fallen from the tree for some reason, but its tough luck was our good fortune. Note its pinkish-rosy belly, and had you been there, you would have seen how the caterpillar thrashed violently side to side when handled.

It turned out to be the larva of the Ilia underwing moth, Catocala ilia, and it was quite unharmed. The cat quickly climbed back up the trunk of the pine a few feet, then froze in place. This is not a small caterpillar - two or so inches in length - but look how well it blends with the bark. Ilia underwing caterpillars, at least in some forms, are lichen mimics and this one surely does match the lichen-encrusted bark very well.

Now to Jack Hoying's incredible images. You may have seen the moth above before, perhaps around night lights. It's a hickory tussock moth, Lophocampa caryae, and they're quite common. But you'll seldom see images of this quality, of any moth. Jack happened along and caught the moth in the act of laying her eggs on this oak. How many eggs do you think there are? More than you might guesstimate, I'd bet - probably a few hundred.

Many moth species essentially carpet-bomb the foliage with their eggs. Caterpillar predators are so varied and prolific that producing scads of eggs is the only way of ensuring that one or a few make it to the stage of the flighted adult and reproductive maturity.

Jack went out to investigate the tussock moth's nursery leaf last night, and it turns out he timed his visit beautifully. He caught the tiny caterpillars just as they had emerged from their even tinier jewel-like egg cases.

At this early stage, the caterpillars are said to be in their first instar. They'll molt several times before reaching maturity, and after each shed will emerge larger. But with each passing instar stage, their ranks will be greatly reduced. Birds, parasitoid flies and wasps, and other predators will pick them off. Caterpillars are Nature's hotdogs - prime sources of protein for all manner of animals, including those warblers that we all know and love.

Jack's photo series is amazing; a captivating window into a little-seen forest animal. But hickory tussock moths are abundant, and this scene plays out millions of times each summer throughout Ohio. Most of us just never notice.

I took this photo of a fully grown hickory tussock caterpillar a few years ago in southern Ohio. It is hundreds of times larger than the fry that Jack photo-documented, and with luck, a few of the animals in his photos will reach this stage.


Jennifer and Steve said...

We LOOOOOOOOOOVE cats too! :) Hope you are well! See you soon.

A.L. Gibson said...

Great post, Jim! I really need to get more in the habit of photographing these alien wonders.

Wish you could have continued on with Dan, Brian and I as we ended up hiking some of Dave Minney's property and found a new population of Trifolium reflexum in Dave's newly burned field. Dan "the clover kid" Boone strikes again!

Rick said...

I have emailed info@nettiebay a couple times,but no response.

Jim McCormac said...

Hi Rick,

I'm glad that you're interested in visiting Michigan with us! I've sent Jackie at NettieBay an email - she may be in Tennessee, but I'm sure she'll get with you upon return.