July 14, 2003


Bright yellow caterpillar with a black racing stripe. I struck out trying to find it in Google (but got an amusing number of tractor sites ;-). Neither of our field guides to butterflies has a single picture of a caterpillar.

Anybody know what this pretty little guy is?

Posted by jeffy at July 14, 2003 11:47 PM

Hey! I've been trying to find out what these little guys are since the early sixties! I saw one two days ago, and the last time was over forty years ago. Please let me know if you find out what they are.

Posted by: GS Monks at August 12, 2004 08:34 PM

Your "caterpillar" is not a caterpillar, but rather the larva of the elm sawfly.

Posted by: Terry Thormin at August 13, 2004 07:57 AM

Unreal! I know a bit about insects, including caterpillars, and this thing is built exactly like your classic caterpillar! Still, what it is doesn't take away from its pretty appearance.

Posted by: GS Monks at August 13, 2004 10:11 AM


Posted by: GS Monks at August 13, 2004 10:13 AM

Sure enough, that's the guy!

Thanks to GS Monks and Terry Thormin for solving this little mystery.

I wonder what the technical definition of "caterpillar" is. It would be a subset of larva, no?

Anyway, it's great to have a name to go with the beastie.

Posted by: jeffy at August 13, 2004 03:22 PM

Actually, there are a few criteria for what makes a caterpillar.

A real caterpillar has six pointy front legs, that it retains as an adult. Next come eight stubbies for walking and gripping. At the end there is another big pair. All these last legs vanish in the pupa or chrysalis stage.

Our critter has extra middle stubby leggy grippy things.

What's creepy here is that a Sawfly is a kind of wasp, and I'm not talking White Anglo Saxon Protestant, here. And most wasp and bee larvae are helpless things that require care by adults. Even solitary wasps hide their young in little hidey-holes.

But a wasp with a caterpillar-like larva that has complete autonomy in the mobility department, that looks and behaves just like a caterpillar, is really strange.

Wonder how they go with Tostidos and salsa?

Posted by: GS Monks at August 13, 2004 07:54 PM

By the way, hope you don't mind, but I snagged your first photo for wallpaper. Looks great! The Caterpillar That Isn't!

Posted by: GS Monks at August 13, 2004 07:58 PM

In case you're interested, here's what our critter looks like as an adult:


Posted by: GS Monks at August 13, 2004 08:08 PM