The berberis sawfly (Arge berberidis) is a non-native, invasive pest that was first recorded in Europe around 2000. It is a highly specialized threat, specifically targeting Berberis (barberry) and Mahonia shrubs. While the adults are completely harmless to humans, their caterpillar-like larvae are voracious defoliators capable of stripping entire bushes bare in a matter of days. Despite their wasp-like warning coloration, sawflies lack the signature narrow “wasp waist” and possess no stinger. Instead, they belong to an ancient lineage within the same order (Hymenoptera) as ants, bees, and true wasps. Depending on the local climate, this species can produce up to three generations per year, with adults flying from May to October to saw open leaf margins and deposit their eggs directly inside. I photographed this sleek adult in the garden of my family’s summer house by the lake in Serock, Poland.