Cocoon Conundrum, and the Importance of Having Smart Friends

One of the neatest things about being interested in all sorts of different things, and living long enough to investigate a few of them, is that you get to know lots of smart people who actually do know a lot of things about a lot of things. Then, when you have questions, you just might know someone to ask – someone who knows what they’re talking about.

Last Thursday, I stopped to notice the long fruit of a 30-foot catalpa tree near the studio. The tree was in full, pre-autumn leaf.

The next day I marveled at the same catalpa tree, now 99% denuded, and populated by hundreds of fat, 3 to 4-inch long, yellow-sided tire-tread hornworms, along with thousands of smaller ones. A few dozen of various sizes had already been wasp-stung, with parasitic eggs hanging off of their paralyzed bodies.

A fan of Lepidoptera, those colorful flying insects we call moths and butterflies, I did a quick Internet image search of the hornworm caterpillars, and came up (correctly, yea me) with the Catalpa Sphinx Moth. 

The ID confirmed, I didn’t bother to read far enough to familiarize myself with the life cycle of this particular species. Moth caterpillars make cocoons. Nuf sed.

On Saturday I returned to the tree, expecting to see the stripped catalpa branches now decorated with some manner of woolly ornamentation.

Not so. There were no cocoons at all, anywhere. No caterpillars, either, for that matter. The paralyzed ones were still there, but the hundreds, thousands of crawlers that had blackened the branches 24 hours earlier, were gone.

Did all of the caterpillars become bird food, or did they crawl somewhere else to metamorphose? If birds are to blame, why didn't they eat the paralyzed caterpillars – with a side of eggs?

I didn’t know.

Fortunately, I know a guy who probably did. A guy who knows a lot about caterpillars.

A quick e-mail to friend Mike Howell, Professor Emeritus of Biology at Samford University, and heralded expert in all things Lepidopterous.

Mike answered my question (and corrected my error in the life cycle of parasitic wasps) by sending me a couple of pages from his latest book on the subject, Uncommon Beauty: The Beauty of Common Organisms by Kurt E. Johnson and W. Mike Howell. (Click to enlarge):

(I told you it was neat to know smart people.)

Professor Howell's new book is available at the Samford University Bookstore.