Tuesday, September 9, 2014


Note: This program first aired on September 6, 2014.

I am a vegetable gardener and this year I went out of my way to pick a tomato variety that would yield large and plentiful fruits. I am lucky enough to have a green house, and though I don’t give my tomatoes all the attention they deserve, they thrive in the heat and grow to heights well above my head. My peppers do just as well, and year after year I am amazed that such large and productive plants can grow from such tiny seeds.

The end of summer is always a whirlwind of activity, and this year was no different. I walked into the green house last week after several days away and noticed some of my pepper plants seemed to be missing a lot of leaves. Then I noticed many dark green blobs and blotches on the soil under the plants, and it slowly dawned on me that something was eating my pepper plants, and I knew just what it was. With a search image in my head, I quickly found the unbelievably large caterpillars that were munching away, confirming my fears. The hornworms are back.

The hornworms in this case are Tobacco Hornworms, Manduca sexta . They and their closely related cousins Tomato Hornworms, are common garden pests, generally showing up on tomato plants in late summer, capable of defoliating a plant seemingly overnight. If you aren’t paying attention at just the right time, you can lose all of your tomato plants. We tend to find them on tomatoes, but they feed preferentially on most members of the Solanaceae including tomatoes, peppers, potatoes and tobacco.

If you have never seen one, they are amazing looking, and sort of freaky. They grow to a size larger in length and diameter than my finger, and according to one source, can actually bite when attacked. Some how I never seem to see one when they are small, but they do start out that way. They are the larvae of Sphinx moths, large nocturnal moths that lay eggs on the host plant in summer. After a few days the eggs hatch and the larvae emerge, feeding for three weeks, and apparently growing from a tiny hatchling, to a caterpillar larger than my finger. They then pupate in the soil, burrowing under the surface and remaining there for at least three weeks. In the first generation of the summer the adults emerge in three weeks. Those adults then mate and lay eggs, and that second generation pupates and overwinters in the soil, with the adults emerging in late spring or summer of the next year. And just like the larvae when they are small, I never seem to see the adult moths either.

The crux of the matter is this, my feelings about the hornworms are complicated. On one level, they are amazing. Huge puffy green caterpillars with beautiful markings and bizarre appendages, they are hard to draw your eyes away from. On another level they are pests, they destroy my tomatoes and are so well camouflaged you are never sure you found them all. When I do find one, I invoke the circle of life and feed it to my chickens. On a final, and more visceral level, I find them disgusting. Though I know better, when I see them I feel a distinct physical sensation in the pit of my stomach, it’s revulsion. Something in my animal brain reacts badly to these enormous grub like larvae, even when my human brain says “wow! Cool!” quickly followed by “darn those pests!”.  I take it to mean that there is something in my evolutionary history that is speaking up, something that is telling me not to eat these hornworms, and I don’t have any way to assure my animal brain not to worry, there is no chance of that. So I am left simply with this strange tension between the very old and the very new. If we pay close attention, I think we will find this tension in many parts of our lives. Whether or not we can rectify it, it is worth being aware of. It’s a window that allows us to look at where we came from, how we lived, and how far we have come from that today.