Pupae overwinter in soil and plant litter. Adults emerge in spring and lay up to 400 eggs singly on the undersides of swallow-wort leaves or leaf petioles. Hatching larvae feed on swallow-wort leaves through five instars. Early instars strip the photosynthetic tissue off leaves while leaving the upper leaf cuticle and epidermis intact, creating a “window-pane” effect, while later instars skeletonize leaves by feeding on all leaf tissue between the largest veins. Fifth instars prepare pupation sites by constructing a silk chamber either on leaves or in the soil or leaf litter. New adults emerge in late summer. There can be up to two overlapping generations per year, depending on temperature and the length of the growing season. Laboratory development time from egg to adult is 5–6 weeks on average. In Canada, two generations have been observed. If the insect establishes in the USA, a similar pattern of two generations is expected in northern states (e.g., New York and Michigan) whereas further south, a single generation is more likely.