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
Nin Jiom Pei Pa Koa in 1962, and continue to manufacture and sell the product worldwide. "Pei pa koa" had annual sales of HK$350 million in 2014. A study at the China Academy of Traditional Chinese Medicine published in a 1994 article, "Pharmacological studies of nin jion pei pa koa", states that Nin Jiom Pei Pa Koa had significant cough relieving and sputum removing effects. In four acute or sub-acute inflammatory models, the anti-inflammatory effect was marked.." "Pei pa koa" is made up of a blend of herbal ingredients including the fritillary bulb ("Bulbus fritillariae cirrhosae", 川貝母), loquat leaf ("Eriobotrya japonica", 枇鈀葉), ladybell root ("Adenophora