Celastrina argiolus | Holly Blue | Gormán cuilinn

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 Holly blue is not afforded legal protection.

Native status


Species Biology


Key identification features:

  • Small size, wingspan: 26 - 34 mm
  • Light blue colour with an absence of orange spots on the underside of the wings
  • Typically flies above 1.5 m along hedgerows and treelines


Generalist, oak woodland, field margins, hedges, urban parks and gardens. Both sexes bask in sunshine on leaves of trees and bushes, with the wings half open. They also fly in sunshine around the tops of trees and bushes, the males occasionally descending to ground level to feed on damp surfaces. Adults spend much time perched on shiny leaves of species such as Holly (Ilex aquifolium) and Laurel (Laurus nobilis), where the shiny-blue of the wing underside makes them difficult to detect (Bond & Gittings, 2008).

Flight period

Bivoltine: the 1st generation typically flies from April to May, with the 2nd generation in flight from July to September.  The 2nd generation is very rarely occurs in northern counties.  When conditions allow, partial 3rd generations have been recorded in Cork City and Dublin City (Bond & Gittings, 2008).

Life stages

Life cycle

Eggs are laid at the base of an unopened flower bud of the foodplant. The larva feeds initially on the unopened buds of its foodplant, on Holly female plants later on the drupes, but on young and tender leaves on male plants, which are generally preferred. Feeding occurs in late May and June, and again from mid-August to September. Ants have been recorded attending the larvae. Pupation occurs July and again in October, in tangled roots and leaf-debris in Ivy, but firstbrood larvae may pupate on the  undersides of holly leaves. This species overwinters as a pupa (Bond & Gittings, 2008).

Food plants

Specialist, the larvae of the 1st generation feed on Holly (Ilex aquifolium), while the 2nd generation feed on Ivy (Hedera helix).

Flowers visited

Generalist, the adult’s nectar sources include: Bramble (Rubus fruticosus), Bugle (Ajuga reptans), Buttercups (Ranunculus spp.), Forget-me-not (Myosotis spp.), Holly (Ilex spp.), Honeydew / Sap, Ivy (Hedera helix), Privet (Ligustrum vulgare), Thistles (Cirsium spp. and Carduus spp.) and Water Mint (Mentha aquatica).


World distribution(GBIF)

It is a Holarctic species found in Europe, Asia and North America (Nash et al. 2008).

Irish distribution

Widely distributed in the southern half of the country, less widespread in the northern half. 

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.