Polyommatus icarus | Common Blue | Gormán coiteann

Pre 2017

2017 - 2021


Conservation status

Ireland: Least Concern (Regan et al., 2010)
Europe: Least Concern (van Swaay et al., 2010)
Climate risk category: Potential Climate Change Risk; present distribution in Europe can be explained by climate to only a limited extent (Settele et al., 2008)

Legal status

The Common Blue is not afforded legal protection.

Native status


Species Biology


The key identification features are;

  • Small size, wingspan: 29 - 36 mm
  • Male, deep blue colour on upperside of wings; female, blue/brown with orange spots along margins on upperside of wings
  • Orange spots on underside of wings
  • Flying low over the ground


Generalist, found on unimproved dry calcareous grassland, coastal grey dunes, machair, dune slacks, vegetated sea-cliffs, limestone pavement, calcareous moraine and scree.  Adults fly actively in sunshine, generally fairly close to the ground, unlike
Holly Blue (Celastrina argiolus); visiting a wide range of flowers of low herbs. In dull weather they roost on grass stems. At night they roost communally in similar situations, head downwards (Bond & Gittings, 2008).

Flight period

Bivoltine: the 1st generation typically flies from April to July, and the 2nd generation from July to September, with a slight overlap in generation in July. In some northern counties, the species has a single generation from June to August.

Life cycle

Eggs are laid on the foliage of the foodplant, usually on the upper surface and towards the base, but sometimes on the leaf axils. Dense young foliage of young plants is particularly favoured. The female sometimes also lays a number of eggs on species other than the foodplants. The larva feeds from June onwards, with some larvae pupating in July while others continue feeding and enter hibernation from September or October, in both cases feeding again in late March and April. The overwintering larva remains low down on a stem of the foodplant, on adjacent herbage or on leaflitter until pupation in May. It is reported that the last-instar larva is milked by ants (Bond & Gittings, 2008).

Threats faced

Specialist, in Ireland the main larval foodplant is Bird's-foot Trefoil (Lotus corniculatus).

Flowers visited

Generalist, the adult’s nectar sources include: Bird's-foot Trefoil (Lotus corniculatus), Bugle (Ajuga reptans), Carline Thistle (Carlina vulgaris), Fleabane (Pulicaria dysenterica), Kidney Vetch (Anthyllis vulneraria), Knapweeds (Centaurea spp.), Marjoram (Origanum vulgare), Ragwort (Senecio jacobaea), Thistles (Cirsium spp. and Carduus spp.), Thyme (Thymus polytrichus), Vetches (Vicia spp.) and White Clover (Trifolium repens).


World distribution(GBIF)

It is a Palaearctic species, its western distribution covering North Africa, the Canary Islands and the whole of Europe (Nash et al. 2008)

Irish distribution

Throughout Ireland. Found where bird's-foot trefoil grows. Common in well drained waste ground and disused quarries. 

Temporal change

Records submitted to Data Centre in 2021

The following map is interactive. If you would prefer to view it full screen then click here.



Bond, K.G.M. and Gittings, T. 2008. Database of Irish Lepidoptera. 1 - Macrohabitats, microsites and traits of Noctuidae and butterflies. Irish Wildlife Manuals, No. 35. National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government, Dublin, Ireland.

Regan, E.C., Nelson, B., Aldwell, B., Bertrand, C., Bond, K., Harding, J., Nash, D., Nixon, D. and Wilson, C.J. 2010. Ireland Red List No. 4 – Butterflies. National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government, Ireland.

Settele, J., Kudrna, O., Harpke, A., Kühn, I., Van Swaay, C., Verovnik, R., Warren, M.S., Wiemers, M., Hanspach, J., Hickler, T. and Kühn, E. 2008. Climatic risk atlas of European butterflies. Sofia-Moscow: Pensoft.

Van Swaay, C., Cuttelod, A., Collins, S., Maes, D., López Munguira, M., Šašic, M., Settele, J., Verovnik, R., Verstrael, T., Warren, M., Wiemers, M. and Wynhof, I. 2010. European Red List of Butterflies. Luxembourg: Publications Office of the European Union.