Stinging Nettle Caterpillar Confirmed on Kauai

By Wendy Osher

Nettle caterpillar, Photo courtesy R. Heu, HDOA.

The stinging nettle caterpillar, which already has established populations on Maui, O’ahu and the Big Island, has now been found on Kaua’i.  State officials say the invasive species was found at a plant nursery on Kaua’i in August 2010.

Since then, adult months of the species were found in Wailua, Kapa’a and Kilauea.  State workers continue to monitor 35 pheromone traps set up at various locations across the island.

The spike covered caterpillar delivers a painful sting when it makes contact with skin, posing breathing complications for those that are allergic, and creating a nuisance for some 45 plant species that it can feed on.

Officials with the state Department of Agriculture say residents on the Garden Isle may begin to see more of the pest during the peak summer months, and are asking the public’s help in reporting possible infestations.

The caterpillar, also known by its scientific name as Darna pallivitta, grows to about an inch in length.  In addition to spikes, it also has a long stripe running down its back.

Aroplectrus dimerus wasp, photo courtesy HDOA.

To help control the pest, the Hawaii Department of Agriculture (HDOA), released a natural enemy of the nettle caterpillar, the tiny Aroplectrus dimerus wasp, which has been successful in controlling the species on other islands. More than 600 wasps were released on Kaua’i between October 2010 and May 2011.  The wasp, no larger than a gnat, lays its eggs on the caterpillar, feeding off of the nettle caterpillar larvae.

Agricultural officials say testing indicates the wasp is host specific to the nettle caterpillar and does not pose a potential threat to non-target organism.

Reports of nettle sightings on Kaua’i can be made to the Pest Hotline at 643-PEST (7378).

*** Supporting information courtesy State Department of Agriculture.