Northern Brown Argus

Aricia artaxerxes


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Aricia artaxerxes

Male, Switzerland, September 2017

Aricia artaxerxes

Male, Switzerland, October 2014

Aricia artaxerxes

Male, Switzerland, June 2018


Aricia artaxerxes

Male, Switzerland, July 2019

Aricia artaxerxes

Male, Switzerland, July 2016


Aricia artaxerxes


Male, Switzerland, August 2014

Aricia artaxerxes

Male, Switzerland, June 2012

Aricia artaxerxes

Male, Switzerland, July 2012

Aricia artaxerxes

Male, Switzerland, October 2017

Aricia artaxerxes

Male, Switzerland, June 2011

Aricia artaxerxes

Male, left, with a female common blue, Switzerland, November 2013

Aricia artaxerxes

Male, Switzerland, June 2012

Switzerland, May 2007

Switzerland, May 2007

Switzerland, May 2007

Aricia artaxerxes distribution

Distribution

The name 'northern brown argus' refers to this butterfly's distribution in the UK, where it is found only in Scotland and in the north of England. The Scottish subspecies, Aricia artaxerxes artaxerxes, which I have never seen, is distinguished by having a white discoidal spot on each forewing. The English subspecies, salmacis, lacks this spot, as does the continental subspecies, allous. What were once considered the Pyrenean and Spanish races of this butterfly are now treated as a distinct species, Aricia montensis.

All the photographs above show males of the subspecies allous - I don't seem to have any pictures of females. The butterfly is similar to the brown argus but has noticeably more pointy wings, especially in the male, and greatly diminished orange markings on the forewings. Like the brown argus, the northern brown argus may be distinguished from brown female blues by the complete absence of any blue scales on the wings. Also like that species, the two uppermost spots in the postdiscal sequence on the underside hindwing are slightly separate from the others, forming a colon. There is no cell spot on the underside forewing.The white fringes of the wings are half-chequered - this may be quite conspicuous.

The northern brown argus is a montane species, though in Switzerland it flies as low down as the Rhône Valley, at 500m. Generally, it replaces the brown argus at altitude and in the north of Europe but there are large regions of altitudinal and geographical overlap. The books describe it as single-brooded, flying from June to August or September, and this is true in the mountains in Switzerland. However, it is on the wing into October or even November in the valley and I have always assumed it to be double brooded or more there. The foodplants are various plants in the geranium family, including cranesbills, rock-roses and storksbills. It hibernates as a caterpillar.