Stem borer (Coleoptera: Erotylidae) in Blephilia

In early January 2025, I found an orange larva of this lizard beetle overwintering in a dead stem of the host just above ground level. Over the course of its feeding activities, it had eaten away most of the pith layer lining the interior of the hollow stem. The larva had compacted the resulting frass into a few short (less than 20mm long) and very dense rods, isolated from one another by stretches of empty tunnel 100mm or more in length.

The larva pupated in the stem and the adult emerged in spring. It left behind an elongate-oval exit hole in the stem, whose long axis was parallel to the long axis of the stem, as was typical of erotylid borers I encountered in this study. All characters of the larva and adult I observed were consistent with A. gracilis.