Observers assessed the density and monitored the defoliation, refoliation, and survival of koa (Acacia koa) trees during the 2013-2014 outbreak of the koa moth (Scotorythra paludicola) at Hakalau Forest National Wildlife Refuge. Koa trees were tagged, classified by size class, and assessed on 55 plots (10-m radius) randomly located in two forest types (reforestation and natural forest) near Pedro and Pua Akala roads. Density and size class distribution was also assessed for ohia (Metrosideros polymorpha) trees on each plot. This dataset provides the location data for all plots.