Stem borer (Coleoptera: Mordellidae) in Caulophyllum

I found several larvae in dead stems of the host in winter. Large accumulations of frass that accompanied some of the larvae indicated that the larvae had performed significant feeding in the stems during the prior growing season. After overwintering in the dead stems, some larvae needed to conduct additional feeding in the interiors of their stems in spring in order to reach maturity. I reared a reddish adult from an overwintered larva in late April 2024.