Friday, April 1, 2011

unidentified caterpillar ~ 04/01/11 ~ at home

unidentified woollybear caterpillar
possible Hypercombe, Grammia, or Spilosoma sp.

I collected this one 03/31/11 down in the Carmel Highlands. Coincidentally I saw several others in La Selva Beach in Santa Cruz County on 04/02/11. I've hesitated posting these pics for several reasons, the least of which is I don't know what it is. Indeed, there are many species of all black, fuzzy, tiger moth caterpillars. The term "woollybear" can be generically applied to any fuzzy caterpillar in the Arctiini tribe. I suspect the most recognizable tiger moth caterpillar is the banded woollybear (Pyrrharctia isabella), which is more common in the eastern U.S. but can occasionally be found in CA. What I have is NOT an Isabella tiger moth.

The best way to identify an unknown caterpillar is to raise one and identify the adult. The challenge with this is figuring out what it eats, being patient enough to let it rest and pupate, and having the luck that it doesn't die in the process. I initially tried to feed it oak leaves, but this one didn't seem interested. I offered it some radish tops and it chomped away for a couple days. Then a week ago (I'm posting 04/09/11), I found it curled up on top of the soil in the container. Had it not been curled up I would have thought it was getting ready to pupate. I figured it must have died and was quite sad. By the next morning, it had climbed up the oak twigs. Since then, it's done this several times without eating any more, despite my throwing in a veritable salad of radish tops, lettuce, and dandelion shoots. It's been stormy off and on this past week, so I wonder if this playing dead and climbing is a natural behavior and/or related to the weather.

Finally, in an all black fuzzy caterpillar, I wanted to take a picture of the most distinguishable feature. In the first picture above, those 10 red things are prolegs. Without getting into too much repetition of what can easily be found elsewhere online or in books, lepidopteran larvae have 6 jointed legs and up to 10 prolegs. Caterpillar lookalikes have differing number of prolegs: some beetle larvae have 6 jointed legs and no prolegs; and sawflies (not flies, but wasps) have 6 jointed legs and 12 to 16 prolegs.