RM larva under a māmaki leaf. Photo: Theresa H. Martinson
The Hawaii Department of Agriculture has released a new Pest Advisory for the Ramie Moth (RM).
RM poses a threat to the endemic Kamehameha butterfly by competing for the same native host plant resources, native forests by decimating endemic plants, and is a potential pest of māmaki and olonā grown for agriculture and Native Hawaiian cultural practices.
In November 2018, Department of Land and Natural Resources, Division of Forestry and Wildlife (DLNR-DOFAW) staff discovered unknown caterpillars (larvae) defoliating māmaki in the back of Olowalu, in the West Maui Mountains. Within a week, the same caterpillars were found feeding on māmaki plants in the Olinda Rare Plant Facility in East Maui. Molecular sequencing by the University of Hawaiʻi, Laboratory of Insect Systematics and Biodiversity, and morphological evaluation by Paul Goldstein (United States Department of Agriculture, Systematic Entomology Laboratory) confirmed the identity of Arcte coerula (Guenée, 1852). This represents the first record of the ramie moth (RM) in Hawaiʻi and the United States.
DESCRIPTION
Larvae: Caterpillars (Fig. 1) are often mistaken for Kamehameha butterfly (KB; Vanessa tameamea) caterpillars (Fig. 5, 7, 9) in Hawaiʻi because of their preference for the same native Hawaiian host plants, specifically māmaki. For this reason, we compare images of eggs (Fig. 2, 3) and larvae of the two species (Fig. 4 – 9). Early instar RM larvae (Fig. 4) are green and black in color. As they develop, RM larvae range in size from 2 mm to 100 mm and become vibrant yellow and black with bright orange-red spots and thin white hairs (Fig. 1, 6, 8). Head capsules are usually black but can also be reddish-brown in color (Fig. 6). KB larvae range from 2 mm to 45 mm in length and do not have bright red spots on their side which RM larvae do. KB larvae have thick, short spines on their bodies, as opposed to the thin, long white hairs of RM larvae.
Click here to read the full advisory.