A wet springtime, causing grass to grow faster than usual, is the reason butterfly numbers in Norfolk plummeted this year, according to Norfolk's butterfly recorder.
It comes as common butterflies saw their numbers collapse over the summer nationally, in results from the Big Butterfly Count.
The majority of butterfly species studied as part of the scheme saw their populations fall with some producing their worst numbers since the count began.
Andy Brazil, who has been the county's butterfly recorder since 2006, said: 'It has been a dreadful year, in Norfolk our small tortoiseshells haven't been so bad as other parts of the country, but I'm not saying we had a good year for everything.
Across the country the small tortoiseshell saw a 47pc drop in numbers and the peacock slumped by 42pc with both species recording their second worst years.
Widespread species such as the gatekeeper, comma and small copper experienced their worst summers in the project's history and were down 40pc, 46pc and 30pc respectively compared to last year.
Participants also saw the lowest number of butterflies per count since the scheme began with an average of just 12 butterflies spotted.
These figures were even lower than those experienced during the cold and wet disaster summer of 2012 – the worst year on record for UK butterflies.
But although Butterfly Conservation, which runs the count, said reasons why butterflies have struggled despite favourable summer weather conditions are as yet unclear, Mr Brazil put it down to a wet spring.
'For butterflies who like short grass or those which like particular flowers, that makes it difficult,' said Mr Brazil, who lives in Lakenham.
Butterfly Conservation's head of recording, Richard Fox, added: 'The drop in butterfly numbers this summer has been a shock and is a bit of a mystery. When we have cold, wet summers, as in 2012, we expect butterfly populations to plummet, but that wasn't the case this year.
'The summer months were warmer than usual, yet most Big Butterfly Count participants saw fewer butterflies. Perhaps the very mild winter had a negative effect, or the cold spring, or perhaps the impacts of intensive farming and pesticides are really hitting these common species now.'
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