Regional Species


Brown Argus
Aricia agestis

Photograph by Ilija Vukomanovic

Regional Species

This butterfly has been largely restricted to calcareous areas supporting Common Rockrose (Helianthemum nummularium) - the principal larval foodplant. Indeed the dot distribution map for the species could almost have been used to display the chalk and limestone areas of Britain. Recently, however, there has been a dramatic expansion in range brought about by the occurrence of individuals with a genetic predisposition to use alternative foodplants, such as Dove's-foot Crane's-bill (Geranium molle) and Common Stork's-bill (Erodium cicutarium). Whether or not this implies that the butterfly will spread away from the Carboniferous Limestone in North Wales is not yet known but it may be that, in the not too distant future, the butterfly could become more common on Anglesey and the Lleyn and possibly even extend down the coastline of Cardigan Bay.

There are two broods each year, distinguishing this butterfly from the single brooded Northern Brown Argus. Note, however, that some populations in North Wales are single brooded but, even so, appear to be more closely related to other populations of Brown Argus rather than to the Northern Brown Argus. To further confuse the issue, in 2003, third brood individuals were widely reported.

Rather similar to a female Common Blue but that species usually shows some degree of blue colouration on the wings.