Despite being largely nocturnal and often overlooked, moths must rate as one of the most attractive and interesting groups of garden animals and news of their decline will alarm many gardeners.
Since 1968, the Rothamsted network of light traps has been recording numbers of larger moths caught every night from hundreds of locations across Britain. This provides one of the longest-running and geographically extensive data sets on insect populations anywhere in the world. Analysis of this data set, carried out by Rothamsted Research and Butterfly Conservation
, has generated national population trends for hundreds of common moths for the first time.
The total number of moths recorded in Rothamsted trap samples has declined by a third since 1968. Population trends were generated for 337 moth species. Two thirds (226 species) show a decreasing population trend over the 35 year study. Such widespread declines are likely to be having detrimental knock-on effects on other organisms. 62 moth species became extinct in Britain during the twentieth century and many more species are considered now to be nationally threatened or scarce.
Many factors have been fingered to explain the decline in our moths including changes in the extent and quality of suitable habitat, pesticide use, eutrophication, light pollution and climate change. Regardless of the causes, anything that gardeners can do to encourage and help out these fascinating animals is to be welcomed.