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Butterfly taxonomy (classification) The skippers The swallowtails The whites The hairstreaks, coppers and blues. Includes the Duke of Burgundy. The nymphalids, fritillaries and browns. Includes the Monarch.
08 C. argiolus NZ208002 1405 1 001Wingspan
26 - 34mm
Holly Blue

Celastrina argiolus
Pronunciation sell-us-TRY-nuh
ar-jee-OH-luss
Linnaeus, 1758
Ref: 1580
Superfamily: Papilionoidea
Family: Lycaenidae
Subfamily: Lycaeninae
Genus: Celastrina
Subgenus:  
Species: argiolus
Subspecies:britanna (Verity, 1919)
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Holly Blue - imago - Thatcham - 29-March-09 (2)
Male
Holly Blue 2009 Clive Burrows [Clive Burrows]
Male Underside
08 C. argiolus NZ208002 1405 1 001
Female
Holly Blue - imago - Thatcham - 23-Sep-04 [REARED]
Female Underside

Introduction  

The Holly Blue is primarily found in the southern half of the British Isles, and is a frequent visitor to gardens. This species is renowned for fluctuating wildly in numbers, forming a predictable cycle over a few years, believed to be caused by parasitism from the wasp Listrodomus nycthemerus whose sole host is the Holly Blue. The wasp lays its eggs in Holly Blue larvae, with a single adult wasp eventually emerging from the Holly Blue pupa.

Subspecies: britanna

The population in the British Isles is represented by this subspecies.

Distribution  

This species is found mainly in the south of the British Isles. It is found in England, Wales and Ireland, especially in the south, but is absent from Scotland except as a scarce vagrant.

Annual Cycle  

There are two broods each year, although there may be only one brood in the north. Adults from overwintering pupae emerge as early as the first week of April in a typical year, with the next generation emerging at the end of July and early August.

Subspecies: britanna


Habitat  

This butterfly is found in many different types of habitat, including gardens, churchyards, woodland, parks, and anywhere its foodplants and nectar sources can be found.

Larval Foodplants  

The primary larval foodplants are Holly (Ilex aquifolium) and Ivy (Hedera helix). Bramble (Rubus fruticosus), Dogwoods (various) (Cornus spp.), Gorses (various) (Ulex spp.), Snowberries (various) (Symphoricarpos spp.) and Spindle (Euonymus europaeus) are also used.

Nectar Sources  

Adults feed primarily on Bramble (Rubus fruticosus agg.), 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).

Imago  

The adults are most easy to identify when at rest, since their undersides are distinctive among the blues found in the British Isles, with the possible exception of the Small Blue, which is much scarcer (and, as its name implies, much smaller). The male and female are distinguished by their uppersides, where the forewings of the female have broad black borders that are absent in the male. However, the adults only tend to open their wings in weak sunshine. Second brood females generally have broader black borders than first brood females.

A particular characteristic of this blue is that it will fly high off the ground, distinguishing it from other blues. In this respect, they are more similar in behaviour to a hairstreak.

Both sexes visit a variety of nectar sources such as Bramble, Holly and Forget-me-not. However, they do seem to have a preference for honeydew rather than nectar. The males will also come down to the ground to take salts and minerals from damp mud and animal waste.

Subspecies: britanna


Holly Blue (female)
Photo © Trev Sawyer
Holly Blue - Female - Summer
Holly Blue - Female - Summer - 08/05/2008, Mountstewart, Co Down, Northern Ireland
Photo © Dave McCormick
08 C. argiolus CR 12
Photo © Paul
08 C. argiolus NZ208002 1405 1 001
Photo © Paul
Holly Blue Female - Ballard Down, Dorset 23-May-05
Photo © Vince Massimo
23-May-2005
Holly Blue Male - Crawley, Sussex 15-April-09
Photo © Vince Massimo
15-Apr-2009
Holly Blue Male - Crawley, Sussex 15-April-07
Photo © Vince Massimo
17-Apr-2007
Holly Blue - Female - Egg Laying
Holly Blue - Female - Egg Laying, Mountstewart Co Down, Northern Ireland - 31/05/2008
Photo © Dave McCormick
Holly Blue - imago - Thatcham - 22-Sep-04 (3) [REARED]
Photo © Pete Eeles
22-Sep-2004
Holly Blue - imago - Thatcham - 23-Sep-04 [REARED]
Photo © Pete Eeles
15-Sep-2004
Holly Blue - imago - Thatcham - 29-March-09 (2)
Photo © Pete Eeles
29-Mar-2009
Holly Blue - imago - Ufton Nervet - 21-Apr-07 (1)
Photo © Pete Eeles
21-Apr-2007
Holly Blue - imago - Portsdown - 16-Apr-07 [Alan Thornbury]
Photo © Alan Thornbury
Holly Blue 2009 Clive Burrows [Clive Burrows]
Photo © Clive Burrows
Holly Blue - Magdalen Hill Down - 4 July 2010
Photo © Clive
04-Jul-2010

Aberrations  

Description to be completed

Ovum  

The white eggs are laid singly at the base of unopened flower buds of the foodplant. Eggs laid in spring are typically laid on Holly, whereas the summer eggs are typically laid on Ivy. And so the Ivy Blue would be an equally-appropriate name for this species! In this respect, the Holly Blue is unique in the British Isles, where the different broods use different foodplants. In good years, the eggs can be relatively easy to find on the foodplant and hatch in around 2 weeks.


Holly Blue - ovum - Hartslock - 28-Aug-04
Photo © Pete Eeles
28-Aug-2004
Holly Blue - ovum - Unknown location - 2004 [REARED] [Reg Fry]
Photo © Reg Fry

Larva  

The larva is extremely well camouflaged, and is usually a plain green colour, although some larvae may also have areas that are light pink. The larva is most-easily found by looking for damage to the developing flower buds, where it may usually be found attached to a neighbouring bud. The larva bores a hole in the side of the flower bud and scoops out the content, leaving a succession of empty flower buds, each with an access hole, in its wake. The larva has 3 moults in total.


Holly Blue - larva - Brimpton Canal - 03-Sep-04 (5)
Photo © Pete Eeles
03-Sep-2004
Holly Blue - larva - Thatcham - 01-Oct-08 (4)
Photo © Pete Eeles
01-Oct-2008
Holly Blue - larva - Thatcham - 01-Oct-08 (6)
Photo © Pete Eeles
01-Oct-2008
Holly Blue - larva - Thatcham - 01-Oct-08 (7)
Photo © Pete Eeles
01-Oct-2008
Holly Blue - larva - Thatcham - 30-Sep-08 (2)
Photo © Pete Eeles
30-Sep-2008
Holly Blue - larva - Thatcham - 30-Sep-08 (3)
Photo © Pete Eeles
30-Sep-2008

Pupa  

The larva leaves the foodplant to pupate on or near the ground, and turns mauve in colour prior to pupation. The larva spins a very fine silken girdle to attach itself to the chosen pupation site. Pupae from the spring generation emerge in 2 to 3 weeks, whereas those formed in late summer overwinter.


Holly Blue - pupa - Thatcham - 10-Aug-08 (8) {REARED}
Photo © Pete Eeles
08-Oct-2008
Holly Blue - pupa - Unknown location - 2004 [REARED] [Reg Fry]
Photo © Reg Fry

Similar Species  

Common Blue

Description to be completed

Small Blue

Description to be completed

Videos  

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Sites  

Click here to see the distribution of this species overlaid with specific site information. Alternatively, select one of the sites listed below.

RatingSites
Bedfont Lakes Country Park LNR, Gait Barrows, Meanwood Park
Leighton Moss, Warton Crag
Devils Ditch, Fleam Dyke, Midgham Lakes, Thurlbear Quarrylands
Bovey Valley Woodlands
Mill Hill
Not rated
Arnside Knott, Hounslow Heath LNR, Mayford Pond

Conservation Status  

The population trend of this delightful butterfly is one of a marked increase. It has also spread northward. It is not, therefore, considered a species of conservation concern.

UK BAP StatusDistribution TrendPopulation Trend
Not ListedIncreaseLarge Increase

From The State of Butterflies in Britain and Ireland and the UK Biodiversity Action Plan (UK BAP) (2007 review).


Links  

The following links provide additional information on this butterfly.

References  

The species description provided here has been derived from the author's own observations and the information contained in the following works:

  • A Natural History of British Butterflies, by F.W.Frohawk.
  • British and Irish Butterflies, by Adrian M. Riley
  • South's British Butterflies, by T.G.Howarth (which is based extensively on the classic work, "The Butterflies of the British Isles", by Richard South).
  • The Butterflies of Britain and Ireland, by Jeremy Thomas and Richard Lewington.
  • The Millennium Atlas of Butterflies in Britain and Ireland, by Jim Asher, Martin Warren, Richard Fox, Paul Harding, Gail Jeffcoate, Stephen Jeffcoate.
  • The Moths and Butterflies of Great Britain and Ireland Volume 7 (1) Hesperiidae to Nymphalidae (the Butterflies), by A. Maitland Emmet and John Heath (editors).
  • The State of Butterflies in Britain and Ireland, Richard Fox, Jim Asher, Tom Brereton, David Roy and Martin Warren.

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