Stem borer (Coleoptera: Mordellidae) in Alliaria

In December 2022 I found a young larva overwintering in a tunnel in the pith of a stem. The larva was a pale whitish color, with dorsal ampullae and diminutive paired urogomphi that were triangular in lateral view. I did not rear it to adulthood.

Later, in December 2024 I found similar mordellid larvae overwintering in garlic mustard dead stems in my yard. I reared one of these to adulthood in early 2025. The adult was a very small mordellid, brick-red overall with some darker shades of reddish-black on the outer edges of the elytra and the underside of the second thoracic segment. It left a roundish exit hole in the stem when it emerged.