Inchworms move more quickly than you might think. Intent on trying to photograph patterns on an especially tiny one trucking along a boardwalk at the San Bernard Wildlife Refuge, I assumed a twig had fallen into my hair, and brushed it off. Then, as I brushed away a second and third ‘twig,’ I realized they weren’t bits of a tree branch at all. They were caterpillars.
As the wind rose, the number of falling caterpillars increased, until the boardwalk was covered with them. In only a few hours, hundreds of them were crawling over plants, the decking — and me.
Eventually, I learned I’d encountered the Live Oak Tussock Moth (Orgyia detrita), a moth species whose life cycle coincides with the emergence of Coastal Live Oak leaves in spring. Quercus virginiana serves as their primary host plant, and emerging caterpillars may completely defoliate a tree, although wind-blown Tussock Moths may defoliate other small trees and shrubs; all of the oaks and other plants usually rebound without suffering permanent damage.
The caterpillars, named for the ‘tussocks,’ or tufts of hair on their back, are strikingly pretty. Those tufts are so striking that, when I spotted this caterpillar on Pete Hillman’s nature blog, I suspected his English caterpillar was related to the species I’d found in mid-April.
Indeed, it is. Known in the United Kingdom as the Vapourer, in the United States the non-native species is known as the Rusty Tussock Moth. Like our Live Oak Tussock Moth, the Vapourer feeds on a variety of broad-leaved trees and shrubs throughout woodlands, moorlands, valleys, and urban gardens from northern Scotland to the extreme southwest of Cornwall.
While the Vapourer shares the distinctive hair tufts of our Tussock Moth, its common name refers to the pheromones — the ‘vapours’ — that males follow to find females with which to mate.
The hairs of both species can be irritating to human skin, but there was nothing at all irritating about finding myself in the midst of a caterpillar ‘shower,’ or in the discovery that our native species has an equally attractive counterpart across the Atlantic.