Silver-studded blue

Species of butterfly

The silver studded blue (Plebejus argus) is a butterfly in the family Lycaenidae. It has bright blue wings rimmed in black with white edges and silver spots on its hindwings, lending it the name of the silver studded blue. P. argus can be found across Europe and east across the Palearctic, but it is most often studied in the United Kingdom where the species has experienced a severe decline in population due to habitat loss and fragmentation. The butterfly is adaptable to different habitats and is found in heathland, mossland, and limestone grassland.

The caterpillar of P. argus is green with a dark stripe along the length of its body and can reach 1.3 centimeters in length.

P. argus exhibit sexual dimorphism, as evidenced by the color of their wings. This eventually acts as an important visual cue when searching for suitable mates. Experiments have shown that species that have overlapping habitat distribution and are of similar color (according to the human eye) have distinct absorbance values within the UV range. This shows that the UV range colors are important for butterflies when recognizing members of its own species.

P. argus is found across the Palearctic. Heathlands are able to meet the needs of P. argus due to burning, cutting, and other disruptions of mature heaths. When the weather is warm, sunny, and the breeze is still, P. argus spends less time in shrub dense habitats and more time in flight and finding host plants in areas rich in calcareous heath. These areas tend to be on exposed hillsides. For this reason, it often appears that the habitat of P. argus shifts with weather conditions.

Adult P. argus tend to be very sedentary, only moving around every day. For this reason, the butterflies colonize on discrete territory and patches of land. Some butterflies, though, disperse and move over a kilometer between colonies. This is rare, however, as these butterflies tend to form metapopulations.

Adults feed on nectar. In mosslands, the butterflies tend to lay their eggs on the underside of the fronds of the Bracken Fern. This fern appears to be preferential for oviposition because they attract ants. In limestone grasslands, P. argus lays eggs at the stem of Lotus corniculatus and at the base of Helianthemum chamaecistus.

P. argus adults emerge in the end of June and beginning of July and engage in flight into the beginning of August.

P. a. argus Scandinavia
P. a. aegon (Denis & Schiffermüller, 1775) Karelia
P. a. cleomenes (Fruhstorfer, 1910) Carpathians
P. a. wolgensis (Forster, 1936) southern Europe, Kazakhstan, Tian Shan, Tarbagatai, Saur, southern Altai
P. a. bellus (Herrich Schäffer, 1844) Asia Minor, Kurdistan, Levant, Caucasus, Armenia, Talysh
P. a. obensis (Forster, 1936) Ural, western Siberia
P. a. clarasiaticus (Verity, 1931) eastern Altai, Sayan, Transbbaikalia, western Amur
P. a. pamirus (Forster, 1936) Pamirs Alai, Tian Shan
P. a. coreanus Tutt, 1909 eastern Amur, Ussuri, Korea
P. a. micrargus (Butler, 1878) Japan, Sakhalin
P. a. asur Agenjo, 1966 Villasur, Spain
P. a. bejarensis (Chapman, 1902) Castilla Leon, Béjar, Spain
P. a. branuelasensis (Tutt, 1909) Branuelas, Spain
P. a. casaiacus Chapman, 1907 Casayo, north western Spain
P. a. claraobscura (Verity, 1931) Larche, Basses Alpes, 1700 2000m, France
P. a. seoki Shirozu & Sibitani, 1943 Saishuto, Korea
P. a. vigensis Tutt, 1909 Vigo, north western Spain
P. a. sultana (Forster, 1936) Asia Minor

When a male detects a female sitting quiescently, he flies towards the female. As he approaches the female, he flutters his wings in broad sweeping movements and she raises her abdomen while vibrating her half open wings in a mate refusal posture. The female then flies away and is followed by the male. Once she lands, the male flutters around, either in the air before descending or after landing. Additionally, the percentage of heathland has decreased by over fifty percent in the United Kingdom, greatly affecting the butterflies for which this was a primary habitat. The heathland that remained was reduced in quality due to shifting environmental influences. Rabbits helped keep vegetation short through grazing which was conducive to habitation by P. argus, but in the middle of the twentieth century, a virus, Myxomatosis, caused a significant decline in the population of rabbits and therefore the grass length grew to a point that was no longer conducive to the butterflies.