Attack of the Killer Caterpillars

Author Melissa Koch

A couple of bright yellow caterpillars became a hundred or so, and those hundred quickly became an overwhelming amount. The ground at the ranch was swarming with little yellow caterpillars enthusiastically on their way to any food source. I was taken aback. For such little creatures, they were migrating at an alarming pace. Their appetite was only exceeded by the rapid syncopation of a lot of tiny legs. I had to ask myself, “what the hell is going on? Is this how it ends?” (consequently, my go-to questions in any strange situation). I could almost hear God’s booming voice narrating omnipotently through a white beard, “And the firsteth sign of the end times beganeth with a terrible orange man at the head of great nation. Next, cameth a writhing river of yellow caterpillars leaving the earth barren in its wake.” My post-apocalyptic fantasies faded into curiosity.

A Sample Size of the Hoard

In the years I spent engaged in landscaping, gardening, working at a local nursery, and hiking in the mountains of New Mexico, I had become quite the amateur lepidopterist (I push up my nerd glasses with a snort). I found butterflies and moths fascinating and their successive instar caterpillar stages equally as captivating. At the nursery last season, I discovered two tomato hornworms stripping down our tomatoes (aptly named due to the solitary butt horn). Rather than killing them, I picked them off and fed them at home. My neighbor literally had a jungle of tomatoes growing in our apartment courtyard, and the caterpillars happily ate while in captivity. I watched them blow up in size and resemble an even creepier version of the Michelin Man (I know, it’s hard to imagine there could be a creepier version). Their green poops became mouse-sized. I worried they would escape their container and eat me in my sleep. As they became massive they also took on a brown hue. This signaled it was time to dig into the earth to pupate and then hatch into moths. As moths they would be free to mate and hatch into babies that would ruin some future gardener’s tomatoes. I had to smile, envisioning the long-term prank I’d never witness. I laid them down and they immediately burrowed into the soil to transmogrify. They knew just what to do; nature ALWAYS knows just what to do.

Harry the Hornworm Getting Ready to Dig in and Pupate

Generally, humans have a strong dislike of tomato hornworms because they eat and eat and then eat some more, stripping down precious heirloom tomatoes (the prima donna of vegetable gardens). Some people send them sailing across the yard to starve to death, others squish them, many feed them to their backyard chickens. I may have done this a few times before I became curious as to what these “pests” are and what function they serve in the greater whole. Tomato hornworms (Manduca quinquemaculata) are in the family Sphingidae and may be confused with tobacco hornworms (Manduca Sexta), another Sphingidae moth that also feeds on plants in the Solanaceae family i.e., tobacco, eggplant, peppers, both tomatoes and tomahtoes, and of course potatoes, and also, potahtoes. Sphingidae is better known as sphinx or hawk moths. Therefore, tomato hornworms are, in fact, a kind of sphinx moth. These “pests” are the primary pollinators of datura (Datura Spp. a.k.a. the moon flower made famous by painter Georgia O’Keeffe), evening primrose (Oenthera Spp.), and desert four o’clock (Mirabilis multiflora). All of these are important and beautiful Southwestern native plants.

Unfurling Detura Wrightii with Ant

And now back to the END TIMES:

Strangely, these yellow caterpillars appeared vaguely familiar. Kind of like that person you see at the gas station on a cross country road trip that looks similar to someone you can’t quite remember that may have gone to your childhood church. These, also, had butt horns and so I deduced they were a type of sphinx moth. During my nerd alert search to identify them, I discovered the hoard of yellow caterpillars happens almost every year in the Southern Arizona desert. In fact, some years, they’ve had to close roadways because the caterpillars are so numerous, the road becomes too slick to safely travel.

I was surprised to learn that these caterpillars are the larvae of the white-lined sphinx moth Hyles lineata. They are commonly called hummingbird moths due to their size and the flight pattern their wings. I was a little dismayed, after all, I was no stranger to white-lined sphinx moths so why didn’t I recognize them? As I dove deep into Google, I learned that white-lined larvae coloration can widely vary. Consequently, discovering this alleviated any self-esteem issues that had developed due to my inability to correctly identify the caterpillar. I decided to read further.

It is theorized that the migrating mass is an attempt to find food and softer soil to burrow and pupate. The white-lined sphinx moth is one of the most important pollinators of desert plants in Arizona and the larvae were, at one time, a food source for the Tohono Oodham peoples. Because of their abundance during this time of year, they were scooped up and dried, providing an on-the-go nutritious snack (Olson, 2002).

I feel grateful for the yellow mass of creepiness and its place in the universe. Who knows, maybe when I scrunch down and look at them real close they’re looking up at me thinking what a creep I am. Humans are pretty creepy if you think about it, so I don’t mind.

I’ll leave you with wise words from Carl Olson (2002), an entomologist for the U of A:

Enjoy don’t fear this fantastic display by the insects. Nature is a wonder always if one can just rekindle the interest and enthusiasm for all kinds of life, not just the sterile paranoia that seems to exist in the asphalt neighborhoods of today. These insects are not harmful and represent wildlife that is extremely important to the success and survival of the Sonoran Desert. (para. 7)

I think Carl and I would have made the best of creepy human friends!

Biggest Hornworm I’ve Ever Seen

4 thoughts on “Attack of the Killer Caterpillars

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s