Brown Argus

Common Rock-Rose (halianthemum nummularium)

A bright yellow wildflower found in calcareous (alkaline) soils on well drained grassland, fairly common and widespread where soil conditions are right in the south and East of England, but becoming less common further North.

The five petaled yellow flowers appear May-September, around 15-25mm in size often in clusters.

The Common Rock-rose, provides a good nectar source for Bees and other insects, it is also a primary larval food-plant for the Brown Argus, Green Hairstreak, Northern Brown Argus, and Silver Studded-Blue Butterflies.

Quick Information

Group: Cistaceae.
Family: Rock-rose
Type: Perennial.
Height around: 50mm.
Habitat: Dry Grassland, Rocky areas.
Flowering: May to September.
Photograph right : shows open Rock Rose flower, flower buds and leaves
Photographed : 23rd May 2010.
Location : Barnack Hills and Holes (NNR)

Rock-rose (halianthemum nummularium) Wildflower with yellow flowers

Common Rock-rose (halianthemum nummularium) flower buds and leaves

Brown Argus Butterfly (Aricia agestis)

Found widely across Southern and Central England and Wales, the Brown Argus is a small butterfly, most often found on chalk or limestone grassland, where the common rock-rose, a wildflower on which the caterpillar feeds is present.

Brown Argus butterflies are found in small groups or colonies, and emerge from two broods each season, the first brood emerging early May-June, and the second in late July. Although appearing to be quite active during warm sunny weather each individual very rarely strays above a few meters from where it first emerged.

Brown Argus Butterfly (Aricia agestis) - May - Dunstable Downs

Brown Argus (Aricia agestis) – Dunstable Downs – 2012

Quick Info

Family Group: Lycaenidae.
Subfamily: Lycaeninae.
Status: UK resident
Habitat: Grassy meadows and downs, tracks, old quarries.
Wingspan: around 25mm.
Larvae feed on: Common Rock-rose, Common stork’s-bill.
Photographed: Top – 2nd June Barnack 2011 – Left – 27th May 2012 Dunstable Downs – Right- Bloody Oaks Quarry
Location: Barnack Hills and Holes.

Brown Argus (Aricia agestis)

The upper-wings are mostly brown with orange crescents and white fringe on the outer margins of the fore and hind-wings.

The undersides of the wings at a glance are similar in colour and patten to the common blue, brownish grey with black spots and orange crescents around the outer margins, although there are quite obvious differences once they are pointed out.

The Brown Argus despite it’s colour and name is part of the Lycaenidae Group of butterflies, more commonly known as “Blues”. In Britain this group of species includes:- the “Common Blue”, “Large Blue”, “Silver-Studded Blue”, and the smallest of all British butterflies the “Small Blue”, to name but a few.

Brown Argus butterflies male and female mating

Brown Argus male and female