Social Distancing Week 11. Wall Brown.

Paul writes: every year I see Wall Brown butterflies along the field path next to my house.

They first appear in the later half of  May and remain through to August. I photographed this one a few days ago, it was my first sighting here this year.

The Wall is a lovely bright butterfly when it first emerges and is easy to recognise. The orange and brown pattern and distinctive eyes on both sets of wings make it stand out from other species. The pose in the photograph is how I nearly always see them. Resting on the path with wings three quarters opened. An individual won’t settle for long, its wings will open and close a few times before it sets off again. It keeps to the same area so I usually catch up with it again a bit further along the path.

I tend to think of it as a common species as I see it so regularly in an unremarkable habitat. I looked at a few old books and my 1959 butterfly book describes it as common and widespread throughout England and Wales. However over the last few decades the species has suffered a dramatic decline in numbers and range. The charity Butterfly Conservation now describes it as being widely distributed but rarely occurring in large numbers and having declined substantially over the last decade in many inland areas of central England. It appears to be becoming more of a coastal species, which fits in with my experience as I only live about a mile from the sea.

The warmer climate is thought to be the reason for the decline. Research has shown that caterpillars that normally overwinter are now emerging as adults in September and October. The usual food plants are not available this late in the season so the butterflies never reproduce, hence less caterpillars make in through the winter. Coastal areas are generally cooler than those inland so this behaviour, and the subsequent decline, is more frequent the further away the butterflies are from the coast.

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