British Wildlife Wiki
Brown Argus

Brown Argus - WWC Archives

The Brown Argus (Aricia agestis) is a butterfly with a wide range across the UK.

Appearance, behaviour and distribution[]

Although one of the "Blues" both sexes are brown on the uppersides with a band of orange spots at the border of each wing. They can be mistaken for other female blues but the Brown Argus never has any blue scales at the base of the wings like other female Blues often do. It could also be mistaken for the Northern Brown Argus (Aricia artaxrexes) were it not for the fact that their ranges do not overlap in the UK. The underside has the typical "blue" pattern of a greyish/brownish ground colour with black spots outlined in white and a row of orange spots along the border. This species has seen an expansion in its range in recent years and is widely distributed across southeast England and most of the Midlands with colonies occurring in Wales and as far north as Yorkshire. These northern sites have seen a lot of confusion in recent years with genetic studies looking at various colonies.

Life cycle and food plants[]

Common Rock-rose (Helianthemum nummularium) is the favoured foodplant on Calcareous soils. In other habitats Dove-foot Cranesbill (Geranium molle) and Common Stork's-bill (Erodium cicutarium) are used. as well. Eggs are laid singly on the underside of leaves. The typically slug-like lycid larvae are green with a pale line along each side and always attended by ants. They hibernate as fully grown larvae and pupate the following spring. There are two broods a year in the southern colonies with adults on the wing in May and June and again in late July till mid September but further north they are single brooded and fly in June and July.

Brown Argus TL

When the Brown Argus is active