Please see the Proposal to Study the Ants on Kure Atoll
Recent observations have shown that the "big-headed ant" Pheidole megacephala has become widespread on Green Island. Gordon Nishida and Beth Flint recorded 26,500 ants per square meter at selected sample sites. While this may not be an accurate indication of the average for Green Island, it is indicative of the large numbers of this ant on Green Island. The ants are not native to the Hawaiian Islands; that is, they are an introduced species.
The ants constitute a significant threat to the natural ecosystem on Kure. They successfully attack and destroy most other insects, and are often successful in killing new-hatch chicks and possibly other juvenile megafauna. In addition, by supporting the scale insects that attacks the flora, the ants facilitate destruction of habitat used by other fauna such as the Bonin petrel (BOPE). The following pictures show the ants attacking a sooty tern chick.
The position of the ant in the Kure ecosystem is complex. According to Nishida, the ants feed on the nectar of a scale insect that breeds on the aggressive, introduced plant Verbesina encelioides, which has also overrun the island. The ants protect the scale from parasites and predators. As the V. encelioides populations are reduced by the scale, it moves onto the native naupaka (Scaevola), leaving the typical blackening caused by a fungus growing on the "honeydew" produced by the scales.
The pictures below show the minor worker (left) and the major worker (right). Click for enlargement.