Stem and petiole borer (Coleoptera: Curculionidae) in Osmorhiza

In 2017, I found a larva tunneling near ground level in a lower stem of the host in mid-July. I reared it on carrot, and the adult weevil emerged on 11 September. Determination to species courtesy G. Hanley (pers. comm., after examining specimen in hand, 2022).

Also, in winter 2023-2024, I found a stem of the host that contained an adult Listronotus, dead in its pupation chamber, along with an agromyzid puparium (record 0352) surrounded by the weevil larva's frass. I surmised that the Listronotus larva had packed frass around the puparium while it was creating its pupation chamber. I reared an adult male Melanagromyza from the puparium.

Finally, I have observed one instance of a Listronotus larva (tentatively identified) tunneling in a basal leaf petiole of the host, but I did not record details or take photographs. Such larvae would most likely need to migrate to the main stem or belowground parts of the plant to complete their development.