abstract
The distribution and status of the cosmopolitan crociferfeeding diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) on Marion Island is reassessed based on a short survey of host plants undertaken during the 1991 relief voyage to the island. The original (1986) and current distribution of the species is discussed in the light of a simple thought-experiment concerning colonisation in windswept areas. This model indicates that successful colonisation by small insects of islands in regions with high wind speeds is more likely to occur on the leeward side than on the windward side of such islands. The 1986 distribution of the diamondback moth coincides with the most likely area of colonisation predicted by the model and supports the idea of natural colonisation of Marion Island by P. xylostella.
