Invasive longhorn beetle spreading across Japan

The invasive longhorn beetle, Rubia acuminata (Kubiaka Tsuyakakamikiri), is rapidly expanding its habitat across Japan, posing a significant threat to cherry, plum, peach, and apricot trees. As of August, the species has been confirmed in 22 prefectures, with several new sightings reported this year alone.

In Hiroshima Prefecture, authorities are investigating potential infestations following reports of adult sightings in Hiroshima City. Similarly, Fukui Prefecture recently confirmed its first occurrence this summer, with damage already identified in 49 trees in Oi Town. The larvae of the beetle bore into trees, causing significant decline and potential death, which threatens both scenic landscapes and fruit orchards.

Because the larvae are difficult to detect inside wood, experts advise monitoring for 'frass'—a mixture of excrement and wood dust found at the base of trees. Local governments, including those in Shimane and Tottori, are urging citizens to assist in monitoring and reporting sightings to prevent further spread and protect local agriculture and natural environments.