(Fabricius, 1793)
Northern Brown Argus
Description:
It is difficult to distinguish the Northern Brown Argus from the Brown Argus (A. agestis). However, the location and type of habitat often helps. The Northern Brown Argus occurs in cooler places, at higher altitudes than the Brown Argus, and its range extends much further north. It likes open grasslands or dry vegetation at the edges of woods. It is also more closely bound to calcareous soil than the Brown Argus.
The eggs are laid on various rockroses (Helianthemum spp.), as well as on various crane's-bills (Geranium spp.). The caterpillars feed on the leaves, often attended by Lasius ants. When the caterpillars are half-grown, they hibernate. Pupation takes place in the litter layer.
There is always only one generation.
This butterfly has different subspecies. Over most of its range, A. a. allous occurs, with no white spots on the upperside of the wings and distinct black spots underneath them. The subspecies A. a. artaxerxes that occurs in Scotland and northern England, does have white spots on the wing upperside, while the dark spots on the underside are either absent, or much less obvious. The subspecies on the mountains of the southern part of its range, A. a. montensis looks like A. a. allous, but is bigger.
Habitat:
Alpine grasslands
Dry calcareous grasslands
Mesophile grasslands
Similar species:
Aricia cramera
Aricia agestis
Aricia morronensis