August 2002. Fiji asked for the identification of two moths, the larvae of which were responsible for the complete defoliation of Maninita Island, Tonga in May and June, 2002. This occurred after the island had completely recovered its foliage following Cyclone Waka on January 1st. The respondent said that he had observed severe moth larvae outbreaks on small islands in Fiji’s Mamanuca and Yasawa islands on several occasions, usually following cyclones, but once following a very severe drought. However, none compared to the defoliation on the 6.5 ha Maninita. Maninita is dominated by Pisonia grandis and there was hardly a leaf left on the island thanks to the ‘Pisonia moth’. The second most common tree is Neisosperma oppositifolia which was not affected, the third is Guettarda speciosa which was completely defoliated by another moth larva – ‘Guettarda moth’, see message with photographs.
At least two other trees (Terminalia and Hernandia) were about 50% defoliated each by a different moth species as well as a herb (Woolastonia). A baseline survey was undertaken on the island and this can be downloaded from www.pacificbirds.com – go to Trip Reports Tab. In June, the rats were taken off the island (hopefully) and a follow up `baseline’ survey will be undertaken in a couple of years time.
The moth was identified as a hawk moth (Sphingidae) and appears to be the pink form of Hippotion velox (Fabricius), which is recorded as feeding on two species of Pisonia in Australia (Common 1990). Reference: Common, I.F.B. 1990. Moths of Australia. Melbourne University Press, Carlton, Victoria. The moth is known to feed on Pisonia and many other plants in the Pacific. It is a new record for Tonga, but recorded from Fiji and islands to the west.