Polyommatus eros (Ochsenheimer, 1808)


Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male on the left, together with closed wings P. idas (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, mid-June 2022) [N] Polyommatus eros: Male (Switzerland, Valais, Täschalpe, 2300m, early July 2019) [N] Polyommatus eros: Female (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, egg found in mid-July 2022) [S] Polyommatus eros: Female (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, egg found in mid-July 2022) [S] Polyommatus eros: Female (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, egg found in mid-July 2022) [S] Polyommatus eros: Female (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, egg found in mid-July 2022) [S] Polyommatus eros: Male [S] Polyommatus eros: Female [S] Polyommatus eros: Male [S] Polyommatus eros: Female [S] Polyommatus eros: Mating (above Heiligenblut, Kärnten, Austria, August 2009) [N] Polyommatus eros: Mating (above Heiligenblut, Kärnten, Austria, August 2009) [N] Polyommatus eros: Female with oviposition behaviour on Oxytropis (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Male of ssp. eroides (Bulgaria, Pirin mountains, late July 2013) [N] Polyommatus eros: Male of ssp. eroides (Bulgaria, Pirin mountains, late July 2013) [N] Polyommatus eros: Male of ssp. eroides (Bulgaria, Pirin mountains, late July 2013) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Eggs on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Eggs on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Ovum (Valais, Switzerland) [M] Polyommatus eros: Egg shell and feeding pattern of the L1 (Valais, Switzerland) [N] Polyommatus eros: Empty egg shell on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Egg shells, feeding scars and droppings of a larva in the first instar on Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [S] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1 (Valais, Switzerland) [M] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L1-larva in the end of this instar (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L2-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Young larva (Valais, Switzerland) [N] Polyommatus eros: L3-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L3-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L3-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L3-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L3-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L3-larva hibernating (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L4-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L4-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L4-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L4-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: L4-larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva, just in last instar [S] Polyommatus eros: Larva (northern Ticino) [M] Polyommatus eros: Larva (Valais, Switzerland) [N] Polyommatus eros: Larva (Valais, Switzerland) [N] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Larva (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Prepupa (Switzerland, Valais, Täschalpe, mid-June 2022) [S] Polyommatus eros: Pupa (Valais, Switzerland) [S] Polyommatus eros: Pupa (e.l. rearing, Switzerland, Valais, Täschalpe, 2300m, prepupa found in mid-June 2022) [S] Polyommatus eros: Pupa (e.l. rearing, Switzerland, Valais, Täschalpe, 2300m, prepupa found in mid-June 2022) [S] Polyommatus eros: Pupa (e.l. rearing, Switzerland, Valais, Täschalpe, 2300m, prepupa found in mid-June 2022) [S] Polyommatus eros: Pupa (e.l. rearing, Switzerland, Valais, Täschalpe, 2300m, prepupa found in mid-June 2022) [S] Polyommatus eros: Pupa (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Pupa (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Pupa (e.o. rearing, Switzerland, Valais, Täschalpe, 2300m, eggs found in mid-July 2022) [S] Polyommatus eros: Host plant Oxytropis halleri (Switzerland, Valais, Täschalpe, mid-June 2022) [N] Polyommatus eros: Egg on upper side of a leaf of Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Oviposition plant Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Oviposition plant Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Oviposition plant Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Feeding scars on Oxytropis (Switzerland, Ticino, Passo di Campolungo, 12. May 2007) [N] Polyommatus eros: Oxytropis halleri with feeding scars (Switzerland, Valais, Täschalpe, 7. June 2007) [N] Polyommatus eros: Habitat in the Ticino [N] Polyommatus eros: Larval habitat in the foreground, with oviposition plant Oxytropis halleri (Switzerland, Valais, Täschalpe, 2300m, mid-July 2022) [N] Polyommatus eros: Habitat in the Valais at 2500m above sea level with many eggs and young larvae, early September 2009 [N]

Host plants:
Oviposition occurs especially on Oxytropis species, e.g. O. halleri and O. campestris, but sometimes or regionally also on Lotus alpinus and possibly even other Alpine Fabaceae.

Habitat:
Polyommatus eros inhabits Alpine grasslands and pastures, particularly when interspersed with gappy spots, stones or avalanche tracks, from about 1200 to 2800m above sea level.

Life cycle:
The adults are found in a single generation from mid- or late June to early September, with a maximum in mid- or late July. I observed oviposition in 2700m above sea level in the French Alps (Cime de la Bonette) at Lotus alpinus on gravelled areas with Erebia gorge (July 2005). In northern Ticino, I found at 2000m asl still young caterpillars together with an almost mature one of Polyommatus semiargus on Oxytropis campestris (the latter is probably a new host plant for P. semiargus) in mid-May 2006. In the Valais (Täschalpe), I met two caterpillars on O. halleri at 2200m above sea level on bumps in rather dry, but more recently even at this altitude artificially irrigated meadows - with disastrous consequences for xerophilous species. In the hot year 2022 I recorded last mature larvae and first adults as early as mid-June on the Täschalpe in Valais in 2300m. In mid-July I recorded there many eggs and the last adults.

The larva usually hibernates in the third instar, but after late oviposition in the highest sites may-be also in L2.

Endangerment factors:
Polyommatus eros is less vulnerable in the highest elevations, but has been already extirpated in many lower sites due to excessive mountain agriculture (fertilization, high cattle density), reforestation and tourism facilities.

Remarks:
Polyommatus eros is an Alpine species that occurs in the Pyrenees, Alps, the Apennines and in some mountains in south Eastern Europe (ssp. eroides). In Germany Polyommatus eros is found only in the southern Allgäu Alps (SW-Bavaria). In Poland the small former population of ssp. eroides has disappeared in the meanwhile.



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