Oʻahu nukupuʻu bill to pluck insects found underneath tree bark, the Oahu nukupuu fed on insects on flowering trees such as the koa ("Acacia koa") and ohia ("Metrosideros polymorpha"). These trees attract a large amount of insects due to their nectar-filled flowers. The Oahu nukupuu fed on koa in high elevation forests and fed on ohia in low elevations. The species was believed to have vanished as the spread of disease occurred, killing off nukupuu populations across the islands. In order to control the rat population in the sugar cane fields, mongooses were introduced to Hawaii and were suspected to be predators
Hawaiian tropical rainforests milo ("Thespesia populnea") for the past 1,000–2,000 years. The Polynesian-introduced noni ("Morinda citrifolia"), pia ("Tacca leontopetaloides"), and kī ("Cordyline fruticosa") are also common in this zone. Other native species include pololei ("Ophioglossum concinnum"), ākia ("Wikstroemia" spp.), loulu fan palms ("Pritchardia" spp.), ōhia lehua ("Metrosideros polymorpha"), and lama ("Diospyros sandwicensis"). Mixed mesic forests, at on the windward slopes of the large islands in addition to the summit of Mount Lānaihale on Lānai, receive of rainfall annually and thus may not be true rainforests. The forest canopy, dominated by koa ("Acacia koa") and ōhia lehua ("Metrosideros polymorpha"), is somewhat open, but tree