This is our smallest resident butterfly with a wing span that can be a little as 16mm. The sexes are similar in appearance, although the male upperside is almost black with a dusting of blue scales, whereas the female is more dark brown in colour. Both sexes have an underside that is silvery-grey in colour, and not unlike that of the Holly Blue. This butterfly has a large distribition, being found from northern Scotland to the south of England, with colonies also in Wales and Ireland. However, outside of its strongholds in the south of England, colonies are often isolated pockets, typically in coastal locations. Most colonies consist of less than 30 adults, although a few colonies consist of thousands of adults. This butterfly is absent from the western and northern Scottish isles, the Isle of Man and the Channel Islands.
This species was first defined in Fuessly (1775) as shown here (type locality: Switzerland).
The population trend of this dainty butterfly is considered relatively stable, whereas the distribution trend shows a distinct decline, with the butterfly completely disappearing from some areas. For example, this species is now considered extinct in Northern Ireland with the last sighting in 2001. This species is therefore considered a priority species for conservation efforts.
The table above shows the distribution and population trends of species regularly found in the British Isles. The distribution trend represents a comparison between data for the periods 1995-1999 and 2005-2009. The information provided is taken from the Butterfly Conservation report The State of the UK's Butterflies 2011. The UK BAP status is taken from the UK Biodiversity Action Plan (UK BAP) (2007 review).
Suitable sites for this species are those that are sheltered and contain a good amount of Kidney Vetch, together with grasses and shrubs which are used for perching and roosting. A wide variety of habitats is used, including unimproved chalk and limestone grassland, abandoned quarries, road and railway embankments and woodland rides and clearings.
Click here to see the distribution of this species or here to see the distribution of this species together with specific site information overlaid. Alternatively, select one of the sites listed below.
|Ardersier, Ardley Quarry, Aston Rowant NNR, Aston Upthorpe Downs, Ballard Down, Bishops Itchington, Blue Lagoon, Box Hill, Broadcroft Quarry Reserve, Burnmouth Coast SSSI, Carymoor Environmental Centre, Cissbury Ring, Clubmen's Down, College Lake, Compton Down, Cotley Hill, Dancersend, Dean Hill (West), Devil's Ditch, Dolebury Warren, Draycott Sleights, Dunnet Head, Dunstable Downs, Durlston Country Park, Epsom Downs, Farley Mount Country Park, Feshie Bridge, Fontmell Down, Frog Firle Farm, Grangelands, Greenham Common, Gwrelych Valley, Hod Hill, Hog Cliff Bottom, Holtspur Valley Reserves, Howell Hill, Hutchinsons Bank, Jerry's Hole, Kenfig Pool, Kilvey Hill, Larden Chase, Lein of Garmouth, Lummaton Quarry, Lydden Down, Martin Down, Maryport Harbour, Mumbles Hill, North Bull Island, Old Down, Basingstoke, Old Winchester Hill, Oxwich, Perryfields Quarry, Pewley Downs, Pitstone Hill, Portland Tout Quarry, Prestbury Hill, Raven NNR, Ringstead Bay, Rosslare Harbour, Seaton Cliffs, Seven Barrows, Sewell Cutting, Sharpenhoe Clappers, Sovell Down, Springhead, St Abbs Head, St Bees, St Cyrus, Stoke Camp, Strawberry Banks, Swyncombe Down, The Trundle, Torr Works, Totternhoe Knolls and Quarry, Townsend Quarry, Ufton Fields, Upper Sundon Quarry, Western Heights, Whiteford Burrows, Whiting Ness to Ethie Haven, Windover Hill, Winsdon Hill, Workington, Yoesden Bank|
Adults generally appear in early May in southern sites, reaching a peak at the end of May and start of June. This butterfly has a partial second generation each year, except in northern Scotland.
The chart(s) above have been correlated with the phenology plot below, taken from the UK Butterfly Monitoring Scheme. The blue line gives average counts over the full data set from 1976 to date, and the red line gives the average for the last year.
Both sexes spend a large amount of time basking or resting. Males perch on small shrubs or grass stems which they leave when investigating passing insects or when searching out nectar sources. They are not territorial, however, and can often be found in small groups of 2 or 3. Both sexes take nectar from various flowers, with Kidney Vetch, Bird's-foot Trefoil and Horseshoe Vetch being particular favourites. Males will also take salts and minerals from damp mud, animal droppings and carrion.
Virgin females entering the perching sites are quickly mated without any elaborate courtship. Once mated, the female spends most of her time searching out suitable plants on which to lay and, once found, she lays a single egg between 2 florets on the flower head. She then rubs her abdomen over the flower head which is believed to deter other females from laying on the same plant since the larvae are cannibalistic in their first instar.
Adults feed primarily on Bird's-foot Trefoil (Lotus corniculatus), Kidney Vetch (Anthyllis vulneraria) and Vetches (Vicia spp.).
Several eggs are occasionally found on the same inflorescence, although these will generally have been laid by different females. The eggs are quite easy to find at suitable sites, and hatch in 1 to 3 weeks depending on temperature.
The newly-hatched larva is less than 1mm in length and immediately burrows into a floret where it feeds on the developing seed. As the larvae grow they start to feed outside the floret with their head buried deep inside, with their back end exposed. The larva hibernates on the ground, often under moss or in a crevice in the soil. The larvae emerge in the spring and, without feeding further, wander off to find a suitable pupation site. There are 3 moults in total.
The primary larval foodplant is Kidney Vetch (Anthyllis vulneraria).
The pupa is attached to a grass blade, leaf, or other vegetation, where it is attached to a silk pad by a silk girdle and the cremaster. This stage lasts between 1 and 3 weeks, depending on temperature.
Description to be completed.
This section shows those aberrations for which there is a corresponding image. Click here to see the descriptions of other aberrations for this species.
ab. obsoleta (Tutt.Brit.Butts.1896.p.161.)
= simplex Aigner.Rev.Lapek.1900.p.144.
= paucipuncta Courvoisier.Iris 1912.26.p.63.
The spots of the underside almost obsolete.
ab. semiobsoleta (Tutt.Brit.Lep.1908.X.p.110.)
On the underside the spots of the hindwings reduced to vanishing point or entirely absent. The forewings normal or almost so.
Description to be completed.
The following links provide additional information on this butterfly.
The species description provided here references the following publications: