Petiole borer (Diptera: Agromyzidae) in Arctium

This agromyzid tunnels in the interior of basal leaf petioles 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 tunnel that led from the petiole interior to just under the petiole epidermis, and the anterior spiracles of the puparium penetrated the epidermis. An adult female emerged in early August, 2022.