The Silver-spotted Ghost Moth, also call the Keurboom Moth (Leto venus), one of South Africa’s biggest moths is only found in the temperate forest region of the Southern Cape. Very few are ever seen as it appears not to be strongly attracted to light, seem to fly on wet nights in March to April, have functional mouth parts and cannot live for long as the adult. The larvae are found towards the base of Keurboom (Virgilia) stems and live in tunnels around 30cm long that run parallel to the line of the tree trunk , almost a dead straight tunnel only about six times the length of the larvae and roughly just larger in diameter. This raises the question of what exactly they eat as the wood tunnelled cannot alone contain enough nutrients. Further research is needed to determine just what the larvae are eating but they may “milk” the tree of sap or have symbiotic fungus association. Their presence in a tree is best noted by the “sawdust” that they expel from the top of the tunnel, the exit hole does appear to migrate upwards over time. From growth rings around older parts of the tunnel, it does appear that the larvae live at least four years before pupating and the adult moth emerges from the top exit hole.
My first sight of one of these glorious moths was at home when a neighbour called me to tell me that she had seen a big beautiful moth on the lawn. Big, beautiful it was, also very “tame” and crawled onto my hand! When it flew off, it flew like a wet dish cloth, slowly and weakly.
Since then, several pupae cases have been extracted whole from the bases of Keurbooms, apparently the first photographs of these on public record for many years. Specimens of these empty cases as well as larvae recovered from a tree stem and one adult male were donated to a museum for research and display purposes. Much is still to be discovered about this moth, which now also appears to be a pest on Honeybush Tea farms. Pest it may be, but for those lucky people to have seen a live one, memories to the treasured. Although it does harm Keurbooms, it does not appear to necessarily kill them and trees can survive very heavy larvae infections.