Sir, A year ago I reported that I had seen more than 40 purple emperors in one day in Northamptonshire woods. This year the tally was good but down to about 15.
A field officer for the National Trust told me that his count of emperor eggs in 2010 was only a third of that of the previous year. He attributed this sharp decline to high winds on St Swithun’s Day (July 15) and the following day which adversely affected the female population. In consequence, numbers appear to be down in all the main sites in the country.
In years gone by, we used to start looking for male emperors around St Swithun’s day. Now the males emerge at least two weeks earlier — surely one of many signs from the butterfly world about the reality and effect of global warming.
Prebendary John Woolmer
Cropston, Leics