The euonymus caterpillar was first reported in North America in 1967 in Ontario. This non-native insect is from Europe and is a pest of Euonymus spp. hosts such as European spindle tree (Euonymus europaea), spreading euonymus (E. kiautschovicus), and winged euonymus/burning bush (E. alatus). Interestingly enough, many of these species of euonymus are considered to be invasive plants. Larvae (caterpillars) feed on the leaves of these plants and can completely or partially defoliate their hosts. Extensive webbing created by the caterpillars is shown in a forest understory in Hampshire County, MA that was first invaded by the Euonymus spp. and then taken advantage of by the caterpillars. An infested specimen tree is also shown at a different location. Euonymus caterpillars mature into flying adult spindle ermine moths. Larvae, pupae, and adults are showcased here. Eggs are tiny and difficult to see.