Caterpillar Madness

29 August 2014 by Susan E. Swanberg, posted in Blog Posts

Sphinx moth caterpillar eats the lush monsoon foliage

Sphinx moth caterpillar eats the lush monsoon foliage. Credit: Susan E. Swanberg

During monsoon season in Southern Arizona, the desert is teeming with life. Just this morning, on my way in from feeding the horses, I saw my horned lizard friend and a praying mantis. Horned lizard young hatch during this time of year, so I'll be watching for these miniature desert tanks.

Earlier in the season, a fantastic event occurred, one I hadn’t observed before. I wasn’t quick enough with my camera, and thought I’d lost the opportunity to film the happening until next year.

Fortunately, the white-lined sphinx moth, Hiles lineata, often hatches multiple generations a season, so this week I was able to capture some images of the new horde that descended upon us.

Sphinx moth caterpillars. Credit: Susan E. Swanberg

Sphinx moth caterpillars. Credit: Susan E. Swanberg

“Horde” is no exaggeration. If you find the right spot, you can see hundreds, even thousands of the green-yellow caterpillars eating the lush foliage the monsoons bring.

A member of the moth family Sphingidae, the white-lined sphinx is often called the “hawk moth” or the “hummingbird moth” for reasons you will see in the short video below.

Penicereus greggi, the Night-Blooming Cereus. Credit: Susan E. Swanberg

Penicereus greggii, the Night-Blooming Cereus. Credit: Susan E. Swanberg

An important pollinator of our native plants, including the night-blooming cereus, the white-lined sphinx can often be seen at dusk, hovering around the day’s blossoms. Once the caterpillars reach maturity, they look for a place to pupate.

I followed many a fat caterpillar, trying to find the secret spot where the mysteries of metamorphosis would take place, but just couldn’t find any sphinx moth pupae.

Why? I discovered in my research that the caterpillars pupate underground!

Sphinx moth caterpillar with an orange head. Credit: Susan E. Swanberg

Sphinx moth caterpillars, one with an orange head and the other with a green head. Credit: Susan E. Swanberg

Examine the photos and the video accompanying this post, and you’ll see green-headed sphinx moth caterpillars and orange-headed sphinx moth caterpillars. Are they two different species of sphinx moth, or a normal variation in sphinx moth plaid?

Can you help me solve this mystery, moth experts?


3 Responses to “Caterpillar Madness”

  1. Barbara Reply | Permalink

    Thanks for posting this. We saw many of these on our walk through our subdivision this morning. I had almost despaired of identifying it. A Google image search led me to your post.

  2. Susan E. Swanberg Reply | Permalink

    I'm glad my post helped you identify your unknown caterpillars. I still wonder about the two different versions of the caterpillars I saw. I'm sure they're both sphinx moth caterpillars, but are they the same species? Maybe an expert out there will help clear this up.

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