A survey for scolytine bark and ambrosia beetles undertaken on the entomologically understudied and ecologically devastated Hawaiian island of Lāna‘i, revealed the remarkable presence there of Xyleborus mauiensis Perkins, 1900, an endemic Hawaiian ambrosia beetle in the tribe Xyleborini not previously recorded from the island. Its presence on Lāna‘i ‘fills the gap’ in a distribution encompassing the now isolated islands of Molokai and Maui that together with Lanai composed the single historically large island of Maui Nui more than half a million years ago. We emphasize the reliance of X. mauiensis upon its only known host plant, the endemic Hawaiian Cheirodendron trigynum (Araliaceae), and highlight the conservation importance of ensuring the persistence of even a small number of native plants in environments otherwise dominated by exotic flora. We also report five additional new species records for introduced exotic bark and ambrosia beetles in the tribes Xyleborini and Trypophloeini new to Lāna‘i, discussing their significance to our understanding of the distribution of bark beetles in Hawai‘i. We provide a checklist of all Scolytinae recorded from Lāna‘i to date, together with their known host plants and photographs of the newly recorded beetles together with a map indicating where they were sampled.