The 1970s

Here are the known start and end dates for Emperor seasons between 1975 - 1980 in and around Alice Holt Forest, East Hampshire. This is quite accurate data.

Year        First Sighting        Last Sighting        

1975        5th July                   2nd Aug        

1976        25th June                17th July                 

1977        23rd July                11th Aug                 

1978        15th July                13th Aug

1979        17th July                18th Aug                  

1980        20th July                25th Aug                  

What's interesting - beside the obvious fact that most of those seasons didn't start before mid-July - is how short most were.  

This is because most seasons were curtailed by either extreme heat (1976) or by adverse weather events (in 1977, the adults were knocked out by very cold nights at the start of August; in 1978, they were knocked out by a returning Polar Maritime depression). 

Times have changed...