The Hawaiian Blue butterfly (Udara blackburni) is also known as Blackburn’s Blue butterfly, Blackburn’s Little Blue butterfly, and the Koa butterfly. It is one of two butterflies that are endemic to Hawaii (the other is the Kamehameha butterfly). The caterpillars feed on Acacias, including Koa leaves, hence one of the names. It’s a small butterfly, only an inch or so long, but quite striking.