Predation by the non-native rosy glandina snail "Euglandina rosea" remains a serious threat to the survival of Newcomb's snail. This predatory snail, introduced into Hawai`i in 1955, has established populations throughout the main islands. The rosy glandina feeds on snails and slugs, and field studies document that it readily feeds on native snails found in Hawai`i. Furthermore, the rosy glandina snail exhibits remarkable hunting behaviors leading to capture and predation of submerged prey. Although terrestrial, the rosy glandina will fully immerse itself in water to locate and feed on aquatic molluscs such as Newcomb's snail. The rosy glandina has been observed on the wet, algae-covered rocks of the Makaleha Stream in close proximity to individual Newcomb's snails, and is believed to prey on them. The rosy glandina snail is responsible for the extirpation of many populations and even the extinction of numerous species of native snails throughout the Pacific Islands, and represents a significant threat to the survival of Newcomb's snail.