Petiole borer (Diptera: Agromyzidae) in Arctium

This agromyzid tunnels in the interior of basal leaf petioles of the host during summer. Freshly formed yellow or yellowish-brown puparia occur in late July. In one example I observed, the larva formed its puparium in a shallow chamber at the end of a tunnel that led from the petiole interior to an operculum in the petiole epidermis, and the anterior spiracles of the puparium penetrated the operculum. An adult female emerged in early August, 2022.