Local feeder (Diptera: Tephritidae) in stems of Cirsium

In late June 2024, I found a single spherical stem gall of this insect, not yet fully developed. Later, in late July at the same location, I observed two larvae in side-by-side ovoid chambers in the interior of a second gall. The two larval chambers were mostly smooth-walled, with photos showing a narrow tunnel curving upward through the pith of the gall from one of the chambers. Larvae were squat, plump, and pale yellowish-white, with a dark patch on the posterior end.

In March 2026, I came across an overwintering gall of this species on a dead stem of the host. Dissecting part of the gall revealed a larva inside. In mid-April, the larva formed its puparium, which was straw-colored overall with a darker red hue on both ends. The adult fly emerged on May 21.