First reported from Ontario in 1967, it has become a widespread pest in the Northeast.

A small, narrow, whitish moth with a wingspan slightly under 1 inch (22 mm). The white moth has three longitudinal rows of small, black spots on the forewings, plus a black spot on the collar and a few on the thorax. The subdorsal (trailing edge) row of spots on the forewing usually has larger spots than the subcostal (fore, leading edge) and submedian (middle) rows. The closely related American Ermine Moth, Y. multipunctella, a native species, has more than three longitudinal rows of small black spots on the forewing. In Y. cagnagella, both sexes have gray hindwings, with the fringe pale gray or whitish at the anal angle. Males of Y. multipunctella also have a gray hindwing with a white fringe, but the female has a white hindwing and fringe. Yponomeuta spp. moths may at first be confused with the earlier flying Ethmia spp. (E. longimaculella E. zelleriella). The latter are stouter moths with larger black "spots" (more dash-like). Euonymus, the larval host plant, is called Spindle in Europe.

See UVM Extension Entomology Leaflet 256 from which this description was taken.