Brown
Argus (Aricia agestis)
A. agestis is a widespread, warmth-loving
species and, as such, is typically found in sheltered areas or on south-facing
elevations. It can be found south of a line between Dorset in the west and
southeast Yorkshire in the east, along with colonies in Derbyshire, North Devon
and Cornwall. It is also found in north and south Wales, but is absent from
central Wales. It is not found in Scotland, Ireland or the Isle of Man. Occurring
in small, compact colonies, it is not a great wanderer, only travelling a
couple of hundred metres, at most, from where it originally emerged. Like its
close relative, the Common Blue (Polyommatus icarus), this species
will roost communally on grass stems at night. In fact, the two species are sometimes
found roosting together.
Two
broods are common in central and southern England, with only a partial second
brood in north Wales and the north of England. In good seasons, a partial third
generation may be recorded in the south. The adults emerge first in central and
southern England in early May, peaking at the end of May and the beginning of June,
and giving rise to a second brood that emerges at the end of July. In north
Wales and northern England, the first emergence starts in early June with any
second brood appearing in early August.
Unlike
most other members of the Polyommatinae,
the ‘blues’, the Brown Argus has no blue scales on its upperside, both
sexes being primarily brown in colour as its vernacular name suggests -
although the butterfly can exhibit a bluish sheen when at certain angles to the
light. Both sexes have beautiful orange spots on the upperside of both
forewings and hindwings with the female - illustrated above - being more
generously marked. It appears to be doing well in Sussex this season …
