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

The garden tiger moth (Arctia caja) was once widespread and common in the UK. Data collected using the standard light-traps of the Rothamsted Insect Survey over Great Britain from 1968 to 1998 showed that A. caja abundance fluctuated near 4.2 captures per site until 1983, and then fell 28% to an average of 3.0 captures per site after 1984. The collated index, frequently used to monitor UK butterfly abundance, was not suitable to detect this large, 1-year population change. Four years after the sudden decrease in abundance, the proportion of sites occupied also fell rapidly from an average of 0.60 to an average of 0.42 (30%). Contrary to most UK butterflies, which are expected to increase under the UK climate change scenarios of global warming, linear regression modelling showed that warm, wet winters and springs may be detrimental to A. caja and it is therefore predicted to decrease further. (C) 2002 Elsevier Science Ltd. All rights reserved.