Clover Stem Borer Infestation in Sundial Lupine: Recognition and Consequences

Abstract

The clover stem borer (CSB; Languria mozardi) is a native North American beetle whose larvae develop inside the stems of a broad range of herbaceous host plants, including sundial lupines (Lupinus perennis). Sundial lupine is an imperiled species in many of the jurisdictions where it occurs, and three rare butterfly species depend on it as a larval host plant. As such, sundial lupines are the focus of many conservation projects. Larval damage to the inside of lupine stems reduces pod production, and is thus a threat to the long-term health of lupine populations. Infestations tend to go unnoticed, partly because so much of the insect's life cycle is spent inside the plant stem. Our description of field indicators is intended to help professionals working on lupine conservation projects recognize CSB activity. In Maryland, sites infested with CSB are connected to the anthropogenic meadow network, whereas sites that are not infested are separated from it by a forest buffer.