State officials say many trees in mature koa forests of East Hawaii are losing their leaves due to a sudden, sharp increase in a native moth population.
Koa trees between 2,000 and 4,000 feet above sea level in the Hilo and Hamakua regions appear to be affected.
The Department of Land and Natural Resources said Thursday caterpillars of the koa looper moth are eating the leaves. But department Chairman William Aila says past experience shows koa forests can recover from such outbreaks.
The first outbreak documented in writing occurred in 1892. But oral accounts indicate similar events occurred before.
Nearly 25,000 acres of forest are currently affected.
The department is asking people to report koa defoliation and increased caterpillar or moth abundance observed outside the Hilo and Hamakua areas.