Acrolepiopsis assectella (Zeller), leek moth, is a widespread and common pest of species of Allium L. (Liliaceae) in the western Palaearctic subregion. The establishment of A. assectella in eastern North America has resulted in economic losses to garlic (Allium sativum L.), leek (Allium porrum L.), and onion (Allium cepa L.) growers, especially to organic producers in eastern Ontario and southern Quebec. Acrolepiopsis assectella was first recorded in the Ottawa area in 1993. By 2010, A. assectella had expanded its range into eastern Ontario, southwestern Quebec, Prince Edward Island, and New York. A bioclimate model, using CLIMEX simulation software, was developed to produce mapped results that closely approximated known distributions for A. assectella in central Europe. This model was then validated with recorded distribution records in eastern Europe, Asia, and North America. Model output predicted that A. assectella will readily survive in southeastern Canada and the eastern United States of America. Other areas potentially suitable for A. assectella include coastal regions of the Pacific Northwest, the interior of southern British Columbia, and north-central Mexico. The continued range expansion of A. assectella into other Allium-growing areas of eastern North America appears to be inevitable. Establishment in these areas presents the risk of substantial production losses to Allium spp. producers.