Britain's butterfly numbers fell by more than a fifth across the countryside last year, a study has revealed.
The 22% drop in butterflies in 2011 is thought to be the result of an unusually cold summer and the ongoing deterioration of suitable habitat for the insects, wildlife charity Butterfly Conservation said.
The "wider countryside butterfly survey" involves counting butterflies in more than 700 random one kilometre squares across the UK landscape.
Overall, recorders saw an average of 47 butterflies from seven species per survey made last July and August.
The results are a 22% decrease on the 2010 figures and 41% down on 2009, the first year of the scheme, when recorders spotted an average of 80 butterflies and eight species.
A garden favourite, the small tortoiseshell, did particularly badly last year, with fewer than one butterfly seen per kilometre walked by recorders.
The common blue also struggled, with the butterfly spotted in only a third of the sites surveyed, compared to more than half in 2010.
And the once-widespread wall butterfly was largely absent from central England, the study revealed.
The survey's co-ordinator Dr Zoe Randle said: "The new survey is proving vital in getting better information on how our common butterflies are faring across the countryside as a whole.
"The gloomy results show we need to step up efforts to rebuild a better countryside for butterflies."
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