Large Blue/ Sortplettet Blåfugl

Maculinea arion

Wing span 33-41 mm. Looks like the female of Alcon Blue, but is known for its size, shining blue colour, the black wing-spots and the strong markings on the underside. The spots on the upperside may varie and sometimes lack completely.

Its flying time is in July. The habitat is warm heaths, dunes and pastures. It overwinters as a half-grown caterpillar in nests of the ant species Myrmica sabuleti. The fodderplants of the caterpillar are flower heads of thyme (Thymus) or marjoram (Origanum). When little the caterpillar falls to the ground and is found by an ant, who carries it down in its underground nest. The caterpillar produces a sweet secretion for the ants, while it is eating their eggs and larvaes. The caterpillar transforms into a butterfly in the ant-nest and crawls out from the entrance-hole without any attacks from the ants.

The flight of Large Blue is unsettled and low, but can also be quick, high and goal-oriented, if it is scared. It suns itself in bushes and often seeks nectare at thyme, sheepsbit scabious etc.

Large Blue was almost extinct after 1950. Since 1990 seen only in one spot at Møen and a couple of spots in North Jutland. Listed.

Protection of the species: the locality must not be fertilized, and the vegetation has to be kept low by a suitable management. Any intervention in order to protect the species demands the assistance of specialists.

photo 2007 Høvblege, Møn: stig bachmann nielsen, Naturplan Foto

Brown Argus /Rødplettet Blåfugl

Aricia agestis



Brown Argus has a wing span of 24-28 mm. It is recognizable on the warm chocolat brown upperside with the distinct orange spots, a dark mid spot on the front wing and conspicious dark ribs. The underside looks like the underside of Common Blue, but the upper black spots upon the edge of the back wing are placed above each other like a colon (:). In Common Blue they are displaced. It looks very much like Aricia artaxerxes (Northern Brown Argus), but is smaller and with more distinct spots and more conspicious black spots upon the underside. The Aricia artaxerxes flies however mid between Brown Argus' two generations.

Variation: The numbers and the size of the underside spots varie considerably.

Brown Argus flies mid May until late July and mid July until late August in 2 generations. Sometimes in a 3. generation in September. The flight is whirring and not especially persistent. It seeks nectare on many various flowers. Its habitat is unfertilized pastures, sea cliffs, fallow fields and other dry spots. It wanders about and is often seen far away from the breeding areas. It overwinters as a medium size caterpillar in the vegetation close to the surface. The caterpillar's fodderplants are i.e. cranesbill (Geranium) and storksbill (Erodium cicutarium).

The Brown Argus is locally seen in large numbers in suitable places, in Denmark at Røsnæs or Helgenæs, but the frequency is varied. The species seem to have grown during the latest years with a definite frequency-year in 1995.

Source: Michael Stoltze: Dagsommerfugle i Danmark., 1997.

photo Gl. Ry, Midtjylland august 2010: grethe bachmann

Silver-studded Blue/Argusblåfugl

Plebejus argus



This Blue has a wing span of 20-31 cm. Its characteristic is the strong black spots, clear orange seam band and 4-5 metallic shining eye spots. But else the various Blues are much alike. The male of the Plebejus argus has a broad black seam with a "blurred" border towards the blue. The females are easier to recognize, since they are usually brown with a golden glow, while females of Ida's Blue (Plebejus idas) are more or less blue.



Elsewhere in Europe the argus females have often blue root fields. It is often necessary to use a magnifying glass to see if the argus has a small amber coloured prickle at the tip of the front legs. The Blue species can be difficult to recognize from one another in general, and I haven't used a magnifying glass, but there were many Plebejus argus in Lille Vildmose during this week, and this is one of them. A strong wind was teasing both the Blue and me!



Plebejus argus' flying period is from mid June till late August. Its habitats are heaths and dune-heaths with worn-out vegetation or new sprouts of heather. It overwinters as an egg, which is placed separately at low plants, and the larvae's fodder-plant is low or new sprouts of heather (Calluna vulgaris) and Bell heather ( Erica tetralix), but probably also other low plants.

It is found in spread populations all over Denmark, but is declining everywhere, especially on the islands. Extinct af the island Funen in 1989, but found in isolated populations in a few places on Zealand/Møn/Falster

Source : Michael Stoltze, "Dagsommerfugle i Danmark", 1997.

Photo Lille Vildmose 26 June 2010: grethe bachmann.