Common Blue
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Gosfield
Male. 20 May 2014
Common Blue
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Bison Hill, Beds
Male. 9 June 2013
Common Blue
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Great Yeldham
Male. 21 July 2014
Common Blue
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Great Yeldham
Female. 26 July 2009
Common Blue
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Great Yeldham
Male. 27 July 2013
Common Blue
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Great Yeldham
Male. 27 July 2013
Common Blue
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Great Yeldham
Female. 8 August 2013
Common Blue
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Great Yeldham
Female (same). 8 August 2013
Common Blue
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Roseland House
Female. 12 August 2013
Common Blue
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Roseland House
Same female. 12 August 2013
Common Blue
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Great Yeldham
Male. 13 Aug 2012
Common Blue
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Great Yeldham
Female. 14 Aug 2010
Common Blue
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Canvey Island
Male. 16 Aug 2012
Common Blue
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Aston Rowant, Oxon.
Male. 26 Aug 2012
Common Blue
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Aston Rowant, Oxon.
Male. 26 Aug 2012
Common Blue
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Canvey Island
Pair. 3 Sept 2012

Brown Argus
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Brown Argus.

Brown Argus
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Brown Argus (missing a spot).

Common Blue
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Common Blue.


The Common Blue, Polyommatus icarus

Larval food plants include White Clover and Bird's Foot Trefoil, both of which suffer from overshadowing in uncut grass on fertile soils. South mentions Rest Harrow, Ononis spinosa, a taller plant and more competitive in longer grass, and at Roseland House there is a small wild population of another legume, Meadow Pea Vicia sativa which is able to scramble up through the long grass. The adults were common in 2010 in sheltered corners of the paddock in late July, where they settled on the Creeping Thistles, then in early August favouring the Water Mint as the Thistle flowers decreased. The drop in numbers in 2011 occurred while the paddock was still being grazed, with plenty of White Clover in the short grass. After grazing ceased in 2011 the Clover decreased in the longer grass. Wider mown strips may remedy this.

In the south of England, Common Blues produce two broods per year. The adults flying May and June are from the second brood of eggs laid the previous autumn which have overwintered as larvae. These early summer adults lay the first of brood of eggs, which are on the wing as adults in July to September. In 2010 a peak number of adults on the wing was noticed in Great Yeldham in the second week of August with over half a dozen at a time flying over the Water Mint patch and landing to take nectar.

To identify the males (with blue upper wing surfaces), it is necessary to see that the underside is brown-tinted and has black spots ringed with white, unlike Holly Blues whose underwing surfaces are clearer pale blue, and has small black spots without white rings. The black lines across the white borders of hardly extend onto the blue area at all, unlike Adonis Blues where the black lines extend further.

Females upper wing surfaces are brown or blue, merging into brown towards the margins. If they are the brown version make sure that they have the extra spots on the undersides of the forewings to distinguish them from Brown Argus and that the pair of spots on near the leading edge of the underwings and away from the body are staggered and not closely paired like a colon.

Brown Argus are generally smaller than Common Blues but this character cannot be relied upon as is shown by an extra small Common Blue female in South's plate 106.

Internal links: Home . Butterfly list . Main gallery . Aston Rowant . Canvey Island

External links to the Common Blue pages at: British Butterflies by Steven Cheshire . UK Butterflies by Peter Eeles
Search menu at Cockayne database for forms and aberrations.

Adults in flight: MOST SEEN on ANY ONE DAY in early, mid and late month thirds.
Common Blue sightings at Roseland House, Great Yeldham.
March April May June July August Sept
2011 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 1 1 0 0 0 0
2012 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0
2013 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 3 6 6 1 0 0
2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 1 1 0 0 0

Adults in flight: AVERAGE SIGHTINGS PER COUNTING DAY in early, mid and late month thirds.
Common Blue sightings at Roseland House, Great Yeldham.         All species
March April May June July August Sept
2011 0 0 0 0 0 0 0 0 0 0.3 0.3 0.1 0 0 0 0.3 0.1 0 0 0 0
2012 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 0 0 0 0
2013 0 0 0 0 0 0 0 0 0 0 0 0 0.1 0 0.2 1.5 2.1 2.3 0.6 0 0
2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.7 0.5 0.3 0.1 0 0 0

Weather notes:
2011. July - early August very wet.
2012. April - mid July very wet. August to mid September dry.
2013. Winter wet, March and early April, very cold. The rest of the spring was mostly cold. July, mostly very warm. August, warm.
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6 June 2013