Nettle caterpillar (Darna pallivitta)
The stinging nettle caterpillar, Darna pallivitta, was found in a Panaewa, Hawaii nursery in September 2001. It occurs in Southeast Asia and is known to feed on coconut and other palms and grasses. The caterpillar is covered with spines that produce a burning sensation when it touches the skin. Infestations were found in 10 acres of potted areca palms. Even though the nettle caterpillar was never described as a pest, an eradication attempt was initiated immediately because coconut was a possible host. Despite numerous spray applications of various pesticides by the grower under the guidance of Hawaii Department of Agriculture and University of Hawaii staff, the attempt failed due to the constant (almost daily) rains that plagued the area during that period. Surveys were quickly established to determine the impact of this new pest to Hawaii. Currently, the nettle caterpillar has been recorded to attack over 35 different plants in the Hilo area, including various palms, ti, dracaena, banana, gardenia, mamaki, Hilo grass, mondo grass, coffee, and wiliwili. Surveys have also shown that a Trichogramma sp. egg parasite attacks the eggs of the nettle caterpillar, although not to the extent needed to control this pest. A biological control project has been established for this pest and collaborators have been contacted in Taiwan, Thailand, and Indonesia. Recently, Taiwan researchers have indicated that the best time for parasitoid emergence in their country is in the spring. The adult stage is a moth. Like all moths, the pest primarily spreads by the movement of the adults, which are attracted by light. It could also move on host plants, or as a hitch-hiker on pots, other plants, in vehicles, or by other means.
The nettle caterpillar is primarily an agricultural pest but could also cause serious damage to our environment and losses to our economy. It attacks many different nursery plants as well as those found commonly in existing landscapes. It also attacks coconut which symbolizes our “Paradise of the Pacific” image and could impact tourism. The caterpillar also feeds on a couple of native plants. As populations grow, more native plants are sure to be reported as hosts for this new pest.
Big Island: Nettle catepillars have been caught in pheromone traps in very low numbers up to Volcano and north to Ninole (trapping did not extend beyond these areas). Most of lower Puna and all of South Hilo district are infested . Nettle catepillars occur in Kailua, at the Keahole Agriculture Park and north in landscaped areas.