It’s sometimes hard to believe the stories about caterpillar swarms so large, their leaf crunching wakes people in the mornings. But it’s not difficult to fathom this scenario if you’ve watched a woolly bear gnaw on a leaf, magnified through your macro lens. There’s visible “crunch” in the face. As you see the length of the leaf recede, so you hear the slightest gnashing of caterpillar mandibles.
We saw a few of these woolly guys — Platyprepia virginalis — on a short hike at Bodega Head, on the Sonoma Coast. They’re young Ranchman’s Tiger Moths, overwintering and soon to pupate and become vivid moths. They’re born in the early summer, feast on plants through the fall and winter, then go all polyphagous on the landscape before retreating to the cocoon.
This is the same Bodega Head where last year, we were swarmed with pelicans passing so close overhead, we could hear their wings flapping against Pacific winds. That was a bit later in the season. Last week, we spent most of the walk brushing ticks off our hands and arms, and fording trails overgrown with lupine, thistle and Cream Cups.
Of course, a welcome reprieve from the ticks were these woolly men (or women), slogging through detritus to their next, fresh meal. On first glance, these caterpillars look like skunks. The long silver strands that adorn their backs are skunk tails in miniature. They’re beautiful . . . fattening up to emerge even more stunning as Tiger Moths. Here’s a photo of the Moth-to-Be.
In researching Sonoma woolly bears specifically, I came upon a study in Ecology which looked at the effect of herbivores on invertebrate populations in coastal dune areas. The study determined that whereas jackrabbits reduced the number of woolly bear caterpillars in a plot, deer had the opposite effect, increasing their populations. I wonder if the woolly bears know this.
Additional writings I found suggest that the caterpillars’ mixed diet of plants (polyphagous) contributes to greater growth and survival rates (Ecological Entomology). And that caterpillars like woolly bears might ingest alkaloid plants to fight off parasitic larvae — self-medicating woolly bears.
I love coming upon scientific confirmation of ancient botanical wisdom. Even woolly bears appear to have the cure.