Adonis Blue - Polyommatus bellargus

Scientific Name: Polyommatus bellargus (syn. Lysandra bellargus). The specific name refers to the butterfly's beauty (bellus) and the 'eyes' on the underwings, a reference to the many eyed Argus, a cattle herder and shepherd in Greek myth.

English Name: Adonis Blue.

French Name: Le Bel-Argus or l'Azuré bleu-céleste.

5 Key Characters:
  • wings fringed in white cut by black in a 'ladder' pattern.
  • smallish (forewings 14 - 17 mm long).
  • upperside of the male a brilliant sky blue with a fine black border.
  • upperside of the female brown, often suffused with blue at the base and with orange crescents sitting on black dots on the bottom edge of the hindwing.
  • undersides brown (females more so) with spots.
Lookalikes: Female Adonis Blues are very difficult to distinguish from female Chalkhill Blues P. coridon. The black 'ladder' in the fringe allows you to distinguish the Adonis Blue from the Common Blue P. icarus and Eschers Blue P. escheri.

Habitat: Unimproved grasslands, especially on calcareous soil. Small colonies often survive in surprisingly small habitat remnants such as crop margins and steep banks that are covered in horseshoe vetches.

Caterpillar: small and green with yellow lengthwise stripes, July - May, overwintering as a caterpillar.

Host Plant: Horseshoe Vetch Hippocrepis comosa.

Flight Period: April-May-June-July-August-September.

Status: A typical species of dry calcareous grassland and heath. Very common and very gregarious. It is a Grassland Indicator Species whose population may be increasing although the trend is uncertain. Grassland Indicator Species are monitored in order to be able to assess and predict the ecological health of natural grasslands. This is a conspicuous and easy to see butterfly in the Touraine Loire Valley and Brenne.

Photographed by Loire Valley Nature:

Photographs are numbered from left to right and top to bottom. All photos will enlarge in a new window if you click on them. 1 female laying eggs near Descartes. 2 males nectaring at garden plants in Angles-sur-l'Anglin. 3 - 7 courting behaviour on grassy clearing on a dry limestone ridge near Preuilly-sur-Claise, May. 8 female on Common Birdsfoot Trefoil Lotus corniculatus in our orchard, June.

A male, nectaring on Horseshoe Vetch Hippocrepis comosa.
A male, on White Melilot Trigonella alba.

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