Malacosoma americana

The population of this species on Block Island seems to be highly cyclical. In 2016, the caterpillars caused mass defoliation of black cherry (Prunus serotina) across the island in May; this was before I made any effort to track species abundances at lights. At the Hunt property, an estimated 40–50 individuals were recorded each night July 2 and 3, 2017, but there were never more than about 10 in a night at the same location throughout 2019. Numbers were even lower in 2020, with a maximum of four individuals in a night, and were probably even lower in 2021 based on more limited surveying during the narrow flight window.

Antennae bipectinate in both sexes, but with much larger pectinations in male.