Long-term decline in abundance and distribution of the garden tiger moth (Arctia caja) in Great Britain

Using indices of garden tiger moth Arctia caja abundance derived from the Rothamsted Insect Survey trapping records throughout the UK, the decline in abundance was characterized over a 31-yr period, and the dynamics of the population change were examined and related possibly to meteorological or climatological events. The collated index values showed a long-term, slow decline in the abundance of A. caja, whereas the proportion of sites occupied remained large until 1987. A lag of four breeding seasons occurred between the sudden fall in A. caja density in 1984 and the extinctions of local populations in 1987. Regression analysis revealed that the best predictors of A. caja abundance were winter rainfall and spring temperature, with abundance inversely correlated with both winter rainfall and spring temperature.