Polyommatus thersites (Cantener, 1835)


Polyommatus thersites: Male (N-Greece, Siatista, May 2008) [N] Polyommatus thersites: Male (N-Greece, Siatista, May 2008) [N] Polyommatus thersites: Male (Italy, Abruzzes, Rieti, May 2013) [N] Polyommatus thersites: Male [S] Polyommatus thersites: Adult (Askion, May 2011) [N] Polyommatus thersites: Male (Abruzzes, Rieti, May 2013) [N] Polyommatus thersites: Mating (Askio mountains, Northern Greece, May 2011) [N] Polyommatus thersites: Male [S] Polyommatus thersites: Male [N] Polyommatus thersites: Butterflies on humid ground (P. thersites e.g. on top left, on top right also a Glaucopsyche alexis). Northern Greece, Askion, May 2011. [N] Polyommatus thersites: Lower side [N] Polyommatus thersites: Male [S] Polyommatus thersites: Female (Provence, Massif de la Sainte Baume, late May 2013) [N] Polyommatus thersites: Female (N-Greece, Siatista, May 2008) [N] Polyommatus thersites: Female (Provence, Massif de la Sainte Baume, late May 2013) [N] Polyommatus thersites: Female (N-Greece, Siatista, May 2008) [N] Polyommatus thersites: Female (Provence, Massif de la Sainte Baume, late May 2013) [N] Polyommatus thersites: Female (N-Greece, Siatista, May 2008) [N] Polyommatus thersites: Mating (Massif de la Sainte Baume, late May 2013) [N] Polyommatus thersites: Ovum [S] Polyommatus thersites: Young larva [S] Polyommatus thersites: Female (Provence, Massif de la Sainte Baume, late May 2013) [N] Polyommatus thersites: Raupe (e.o. N-Greece 2008) [S] Polyommatus thersites: Larva (e.o. N-Greece 2008) [S] Polyommatus thersites: Larva (Valais, Switzerland, April 2008) [M] Polyommatus thersites: Larva (Valais, June 2010)) [M] Polyommatus thersites: Larva (Engadine, early July 2010) [M] Polyommatus thersites: Pupa [S] Polyommatus thersites: Pupa dorsal [S] Polyommatus thersites: Pupa [S] Polyommatus thersites: Larval habitat in the Valais (April 2008) [N] Polyommatus thersites: Habitat in Northern Greece (May 2008) [N] Polyommatus thersites: Habitat with quite high population density (Abruzzes, Rieti, May 2013) [N]

Host plants:
The larvae feed on Onobrychis species.

Habitat:
Polyommatus thersites inhabits nutrient-poor meadows with the larval host plant. In the past the butterlie occurred also in agricultural meadows, but these are today over-fertilized and mowed too intense than that Onobrychis or even the butterfly still might exist in them.

Life cycle:
Polyommatus thersites flies in two or three generations from April to October. I found adults of the second generation in the middle of August in the Susa Valley at 900 meters above sea level on extensive meadows and in early May in Northern Greece those of the first generation in grazed grasslands. The caterpillar overwinters. I observed fully-grown caterpillars using the characteristic feeding scars (cuticle remains) in the end of April in the Valais in a nutrient-poor meadow preferred at gappy places hiding at daytime at the base of Onobrychis clumps. The eggs are usually laid on leaves.

Endangerment: strongly endangered

Endangerment factors:
Polyommatus thersites is very rare north of the Alps and occurs locally e.g. at the northern edge of the Swabian Alb or on the Franconian Alb. The butterfly is threatened by habitat loss (succession, but also strong grazing, overbuilding, intensification and eutrophication).

Remarks:
Polyommatus thersites often flies with Polyommatus damon and always together with P. icarus. The overall distribution ranges from Morocco across southern and parts of Central Europe to the east as far as the Tien Shan.



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