Mystery Solved: Tortoise Beetle Larva

Location:  Ventana Canyon, Sonoran Desert, Tucson Arizona
September 2, 2010 8:42 pm
I’m stumped. Some people think it’s a beetle larvae, some a caterpillar with only six legs. Whatever they are they are one of the weirdest things I’ve seen in the Sonoran Desert and that’s saying something. About an inch long maximum, and like being on the underside of the leaves rather than the tops.
Signature:  Sonoran Inquiry

Tortoise Beetle Larva

Hi Sonoran Inquiry,
Was there only one of these things?  What species of plant was it on?  We cannot imagine this being anything but the Larva of a Leaf Beetle.

Tortoise Beetle Larva

While we were at work today, we got numerous identification submissions

How ironic.  I got a couple images of one of these myself the other day, in Pima Canyon, in the same mountain range.  You can thank Margarethe Brummermann for telling me what it was.  Here’s a link with images of more larvae and adults:
Pretty cool, eh?  They are quite large by tortoise beetle standards….

I looked on your website and there was a leaf larva from Thailand? that looked
similar which was a tortoise beetle. I did some googling and think I found it.
It’s the larva for the Arizona Tortoise Beetle (Physonota arizonae). I remember
seeing these beetles in Sabino Canyon, very pretty! Thanks for your help.

Hi Daniel and Sonoran Inquiry:
It does look like a Leaf Beetle larva and I think it is probably a Tortoise Beetle (Chrysomelidae: Cassidinae). I think it might be an Arizona Tortoise Beetle (Physonota arizonae), also known as the Arizona Gold beetle. The Bugguide has a fairly good match, and the site ‘Arizona: Beetles Bugs Birds and more’ has a picture of larvae that look even closer (scroll down a little). The host plant is given as various Asteraceae, but particularly Canyon Ragweed (Ambrosia ambrosioides). If that looks like the right plant (it looks similar from what I can tell) then perhaps this is an Arizona Tortoise Beetle. In any case, I think it something very close to that. Regards.  K

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