Neighborhood Nature

Our Family's Nature Blog

Caterpillar in the Street: Tragedy or Transition? August 26, 2009

Filed under: Animals,Bugs,Plants,Puzzles and Mysteries,Seasons,Summer,Trees — saltthesandbox @ 7:17 pm
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During a break in this afternoon’s rains, I was walking along our street checking for migrant birds. Something caught the corner of my eye — I looked down and found this:

I found this sphinx moth caterpillar laying motionless on the street, under an American Elm tree.

I found this three-inch sphinx moth caterpillar laying motionless on the street, under an American Elm tree. The head is on the left, the hind end (with its horn-like projection) on the right.

We find at least one of these caterpillars each summer, always on the street or sidewalk under an American Elm tree. The green color, overall shape, and especially the pointed projection on the tail convinced me that this must be some kind of hornworm — the caterpillar stage of a sphinx moth.

The caterpillar was motionless. I wondered if it had fallen 30 or 40 feet from the tree above and died. Just in case it was merely stunned, I brought it in our house and put it in a plastic box with some elm leaves. When Ethan and I checked it a few hours later, it was moving its head slowly, stiffly swinging back and forth, so it was still alive. Maybe we could save it!

Then we had a brainstorm. We knew that many hornworms dig into the ground and make a pupa — the transition stage from caterpillar to moth — without spinning a cocoon. And caterpillars often stiffen up before they split their skins, revealing the pupal stage within. Maybe this caterpillar had dropped to the ground on purpose, but had the bad luck to land on the street rather than soft soil. So we added some damp sand to the box, set the caterpillar on the sand, and waited.

Two hours later Ethan checked the box — the caterpillar had disappeared! However, a bit of digging revealed that it had merely dug its way into the sand and curled up into a tight C-shape. We left it alone, because pupating caterpillars can get all messed up if you bother them during this critical transition.

We’ll check again tomorrow and let you know what happened.

—–

Update: The caterpillar continued burrowing in the sand, digging all around the container and finally settling into a rounded cavity just below the surface. Then, after about a week, it died without making a pupa. It turned out to be a tragedy after all. We were very sad.

—–

Follow these links for more information about sphinx moths:

If our caterpillar pupates successfully we’ll have a sphinx moth to identify, which may be easier than identifying a caterpillar or pupa.

 

3 Responses to “Caterpillar in the Street: Tragedy or Transition?”

  1. Jane Says:

    What a great story. Good luck.

  2. Marge Eilers Says:

    Sept 18, 09

    We just found one of these creatures too below a birch tree. We have no elm trees. They will attach themselves by sucking with their jaws onto objects, including clothing and your hand when held. Glad there was a photo. We found this in Renton, Wa.

  3. Kellly Says:

    WE JUST FOUND THE SAME ONE BUT IT WAS ON GRASS
    WE TOOK IT HOME IS IT OKIII


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