Caterpillar damaging Cordia
At a plant nursery in Mangilao, Cordia subcordata trees are being damaged by a small caterpillar, 3 to 7 mm long, which bores into petioles and damages growing tips. Aubrey Moore visited the nursery on May 30, 2008. Caterpillars where collected. Some of these will be reared to the adult stage for identification.
A Note on the Host Plant
The nurseryman identified the host plant as "koa". According to the reference below, "koa" is a common name for Cordia subcordata (Family Boraginaceae) used only on Guam, where it is also known as "niyoron". This plant is very different to what is referred to as "koa" in Hawaii, Acacia koa (Family Fabaceae). It is for reasons such as this that scientific names should be used to prevent confusion.
A systemic insecticide is required to kill this caterpillar. Contact insecticides and those that must be ingested, such as Dipel(r) may not be effective because the caterpillar is protected from contact by its boring behavior.