2025 Volume 28 Issue 3 Pages 90-94
The longhorn beetle, Hirticlytus comosus (Matsushita), is naturally distributed in southern Kagoshima, Kyushu and Kochi, Shikoku. Hirticlytus comosus larvae damage a coniferous tree, Podocarpus macrophyllus (Thunb.) D.Don, commonly used for gardens and hedges. Since it was first recorded in Chiba Prefecture in 2008, the invasive longhorn beetle established populations, raising concerns. In response, Chiba Prefecture has monitored its spread, and Ibaraki Prefecture, north of Chiba, has also recognized the risk of invasion and establishment of the longhorn beetle. Here, we report the first evidence of the invasion of Ibaraki Prefecture by observation of an adult beetle on May 25, 2021, and emergence holes in host trees in 2025. We confirmed the infestation of P. macrophyllus trees by H. comosus at multiple sites in Kamisu City, Ibaraki Prefecture. The presence of large numbers of emergence holes indicates that this species has already established populations in southern Ibaraki. Further investigations into damage caused by H. comosus and development of effective countermeasures are urgently required.
