Thursday, August 21, 2014

Fuzzy Wuzzy Was a Caterpillar

Regardless of what you've been told, the stripes on a woolly bear caterpillar do not predict the severity of an approaching winter, but it may tell you something about the previous winter.  According to Mike Peters, an entomologist at the University of Massachusetts, "There's evidence that the number of brown hairs has to do with the age of the caterpillar—in other words, how late it got going in the spring. The [band] does say something about a heavy winter or an early spring. The only thing is . . . it's telling you about the previous year."¹

I've seen a few woolly bear caterpillars in the last couple of weeks, and all of them were the usual black and brown - black on each end and brown in the middle. But this little guy was just strolling along at breakneck speed (for a caterpillar) in the garden yesterday, with a vertical stripe of black down his back and brown on the sides.

I believe this one is a great tiger moth a.k.a. garden tiger moth (Arctia caja) caterpillar (please correct me if my identification is incorrect!), which is a different genus and species from the woolly bear (Pyrrharctia isabella) with the stripes going the other way. The adult moth generally lays eggs in July and the caterpillars hatch in August. They will spend the winter on the ground in a protected spot and will pupate the following June and July. The adult moths eclose in July and August.

Adult Garden Tiger Moth, resting
Wikipedia/Marek Szczepanek

Adult Garden Tiger Moth

I can't recall seeing an adult, but the most likely time to see one is at night, since like most moths, it's nocturnal. They're also drawn to lights at night, so the next time I turn the light on outside the back door, I'm going to look closer.

AMAZING FACT:  Some woolly bear caterpillars can survive temperatures as cold as -90°F.  Yep, that's a minus sign.

 ¹The Old Farmer's Almanac


RobinL said...

I was trimming a creeping, low juniper last year when I found tiger moth caterpillars. Aren't they lovely?

Beth at PlantPostings said...

Those are hardy caterpillars! And the Garden Tiger Moth is so pretty. I've seen several Wooly Bears lately, and they're middle stripes didn't seem especially thick or thin--which is weird, because last winter was brutal up here in Wisconsin!

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