Native to Asia, box tree moth (Cydalima perspectalis) (Walker) is an invasive pest first detected in Toronto Ontario in November 2018. Present in 36 countries worldwide, the pest is a serious concern to nursery growers and homeowners because it can cause significant defoliation to boxwood (Buxus sp.), its primary host species. Boxwood is an important nursery crop for Ontario and a popular ornamental landscape plant found in residential and public gardens across the province. In 2019 and 2020, monitoring with pheromone traps and ground surveys of boxwoods has helped determine the spread of this pest from its original detection sites in the Toronto area. Two generations of the pest, occurring from May to September have been verified in Ontario compared to 3-5 generations observed in Europe. The larval stage (foliar feeding life stage) was found to be active between mid-May through mid-June and again from mid-July to late August. Beginning in September as day length decreased, larva entered a state of diapause within a protected webbed structure (hibernaria), a critical aspect of their overwintering success. This valuable information is being used to develop a sustainable pest management program that helps to inform the nursery and landscape industry about proper treatment periods to effectively control this invasive pest.