Tuesday, 19 June 2012

Bishop Middleham - Northern Brown Argus

A trip to the North East meant I had a good opportunity to see a 'new' species at the Southern edge of it's range - Northern Brown Argus. A well known and well populated habitat is the Magnesium limestone quarry near Bishop Middleham, not far from Durham.

Arriving mid afternoon, this was one of the 'easiest' and quickest of finds. I found several Northern Brown Argus in the grass adjacent to the path within the first 60 metres after entering the site from the road!

They were easily told from a distance from the equally good numbers of Common Blue - these were noticeably larger, different in flight pattern and of course the males are blue!

Female Common Blue.....

The Northern Brown Argus found here belong to a separate race (salmacis) differing from the Scottish populations in not having a white spot on the upperwing. I wasn't expecting them to be very distinct from bog standard Brown Argus but the white halo on the upperwing from a distance was really noticeable - a white spot indeed!

They were quite variable and some had barely a white mark.....

Here's the underwing pattern......

This was the freshest specimen of the lot! The 'brown' in full sun had an iridescent sheen which was so striking. Unlike Common Blues, the Argus would spread it's wings immediately on landing!

Other butterflies seen included Wall and Dingy Skipper......

Job done, I wish they could all be this easy? Just 13 species to go now to complete the UK list!

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