A comparison between two moth surveys on the farm Zandrivier 559, Lephalale, Limpopo, South Africa.

Two moth surveys conducted during March, a year apart, in the same locality, using a standard protocol, allowed for the gathering of comparative data. The number of specimens and the number of species recorded were almost identical from year to year but the actual species count increased from 264 to 401, an increase of 52%. The high increase in species may be simply an indication of the inefficiency of the sampling method to assess the species richness of an area. Other factors such as the possible influence of differential seasonal rainfall on moth numbers, distance between trap sites and the influence of short adult flight periods are discussed. No definitive conclusions could be reached to explain the high increase in species recorded from year to year. The results from this study questions the validity of species richness assesments for highly diverse taxa such as Lepidoptera, based on short term surveys and cautions their unequivocal use as a benchmark in Environmental Impact Assesments.