Stem borer (Diptera: Agromyzidae) in Boechera

Larvae tunnel in the pith. There may be more than one larva per stem. Pupation is internal, with the puparium evidently being the overwintering stage at least some of the time. Puparia show particularly strong black horns on the posterior spiracular plates, similar to those from Thlaspi arvense (record 0574). Prior to pupation, the larva prepares an exit window in the wall of the stem, through which the adult eventually emerges.

In one extensively tunneled stem I examined in March 2022, three puparia were present: one that was apparently intact; a second, from which the adult fly had failed to emerge; and a third, from which the adult fly had apparently emerged during the growing season in 2021.