Holly Blue

Celastrina argiolus (Linnaeus, 1758)



A small blue butterfly, that is often seen flying high rather than at ground level. The underside is quite distinctive,  being pale grey-blue, with small black spots. The only other butterfly with which it could be confused is Cupido minimus, which is smaller with an almost black upperside. The male has a blue upperside, whereas the female has an obvious black margin to the forewing. 

Habitat Requirements

Found in a wide range of habitats bordered by trees and low growing shrubs, e.g. gardens, grasslands, woodland edges, maquis and garrigue.

Larval Foodplants

Ivy Hedera helix, Holly Ilex aquifolium - doubtfully present, Alder Buckthorn Frangula alnus - not on Corfu, Buckthorn Rhamnus cathartica - not on Corfu, Dogwood Cornus sanguinea, Strawberry Tree Arbutus unedo, Tree Heather Erica arborea (shrub, white flowers), Wild Liquorice Astragalus glycyphyllos, Bladder-senna Colutea arborescens, Goat's-rue Galega officinalis, Lucerne Medicago sativa, Yellow Sweet Clover Melilotus officinalis, False-acacia Robinia pseudoacacia, Spanish Broom Spartium junceum, Wild Privet Ligustrum vulgare, Purple-loosestrife Lythrum salicaria, Hop Humulus lupulus, Firethorn Pyracantha coccinea.


This species is the only truly arboeal blue butterfly on the island and because it is most frequently seen flying in the canopies of low growing trees and bushes it is quite easy to identify. 

In the UK the Holly Blue has a well known dependencey on two common host plants: Holly Ilex aquifolium and Ivy Hedra helix. In Corfu the host plant relationships may be different because we do not have evidence for the existence of I. aquifolium on the island. Instead the first oviposition choice on Corfu is usually the buds of Bramble, Rubus possibly fruticosus. This suggests that in Corfu Rubus may have taken on the same functional role in the life cycle of this butterfly as I. aquifolium has in the UK.

More information about the host plant choices of the Holly Blue in Corfu could be enlightening.

*The information provided in the tables below is based on verified sightings of the Holly Blue submitted via this website since 1st January 2021.

First and Last Sightings

Year First Last/latest # Days
2023 27/02/2023 20/11/2023 266 days
2022 14/02/2022 25/12/2022 314 days
2021 21/02/2021 02/11/2021 254 days

Number of Observations

Year Number of observations
2023 833
2022 425
2021 130
Grand Total 1388

Distribution Map

Distribution maps for this species are currently unavailable.

Flight Times for the Holly Blue (2023)

The chart below shows flight data by month for 2023

Flight Times for the Holly Blue (All Data)

The chart below shows flight data by month since 1st January 2021


  • Vernacular/Common Name: Holly Blue
  • Family: Lycaenidae (Leach, 1815)
  • Sub-family: Polyommatinae (Swainson 1831)
  • Tribe: Polyommatini (Swainson 1831)
  • Sub-tribe: Lycaenopsina ()
  • Genus: Celastrina (Tutt, 1906)
  • Species: argiolus (Linnaeus, 1758)


For a list of references, please see our bibliography page.