The stinging nettle caterpillar, Darna pallivitta, has been found on the Big Island, and now on Oahu. The Department of Agriculture was alerted to its presence on Oahu by a nursery grower who had unwittingly imported infested palm plants from the Big Island where it has been established since 2001. It was intercepted on Maui in plant shipments from the Big Island both at a nursery and in cargo Risk Assessment inspections being carried out as a HISC Prevention project by HDOA from Fiscal Years 2005 and 2006.

The inch-long, spike-covered white caterpillar with a long stripe running down its back packs a painful sting when it comes in contact with the skin. In cases where a person is allergic, more serious symptoms, such as difficult breathing, may also occur. Infestations impact local nurseries as the nettle caterpillar defoliates ornamental nursery stock and has been found feeding on more than 45 species of plants, including palms and coffee.

According to Neil Reimer, manager of the state Plant Pest Control Branch, Plant Quarantine performs visual inspections of propagative plant material moving between islands and requires a "Passed" sticker before this material can move. The larval stage of the moth will possibly be seen with visual inspections, if all leaves are looked at carefully, but it is unlikely that eggs or pupae will be detected. Hot water treatments used by some nurseries to rid plants of unwanted pests do not affect the nettle caterpillar in its pupal, or post-larval, stage.

Preventing the spread of this and other plant pests between the islands has proved difficult. The state Department of Agriculture asks the public, and in particular nurseries, to report sightings of this invasive species to the state's Pest Hotline at 643-PEST (643-7378).

With funding by the HISC Research & Technology Grant Program, scientists from the U.S. Department of Agriculture, Agricultural Research Service (ARS) may have found the perfect pheromone lure for this invasive pest. They have created a synthetic scent imitating the nettle caterpillar's female. The pheromone lure outperformed virgin moths as an attractant for males and may be developed to monitor infestations on the Island of Hawaii and to detect populations throughout the state. Traps created for this study have been sent to Oahu to help in the effort to determine how widespread the moths have become.

Statewide outreach efforts include containment efforts on Oahu, new pest advisories, news coverage, and outreach materials that help educate the public about this invasive species. On Kauai, an Agricultural Pest Workshop was sponsored by the Kauai Invasive Species Committee on December 11, 2006.