On a recent walk I led along the Agawam River Trail for the Wareham Land Trust, I noticed a small clustered group of 3 caterpillars on the underside of a greenbriar (Smilax sp.) leaf. While I normally don’t try to identify most caterpillars, which tend to be small, green and nondescript, these caterpillars were so striking, with their bold black and white markings and yellow undersides that I figured I’d give it a shot. It didn’t take long to pin them down as the larval form of the turbulent phosphila moth (Phosphila turbulenta).

Turbulent phosphila moths fall within the Noctuidae family – a group commonly called owlet moths. Although boldly patterned as a larva, the turbulent phosphila moth with be a mottled, drab brown color as an adult.

It was the caterpillars’ clustering behavior that actually caught my attention in the field. After noticing one Smilax leaf with 3, I found another a few feet away with more than 20. Due to their collective capacity to defoliate vegetation, BugGuide refers to this caterpillar as a “gregarious defoliator”.