Small Blue

Cupido minimus (kew-PY-doh MI-nim-uss)

Small Blue (m) Totternhoe Quarry, Beds; 2nd June 2010
Photo © millerd
 

Wingspan
18 - 27mm

Checklist Number
61.010

Family:LycaenidaeLeach, 1815
Subfamily:PolyommatinaeSwainson, 1827
Tribe:PolyommatiniSwainson, 1827
Genus:CupidoSchrank, 1801
Subgenus:CupidoSchrank, 1801
Species:minimus(Fuessly, 1775)

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Introduction

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.

Cupido minimus

This species was first defined in Fuessly (1775) as shown here (type locality: Switzerland).

Small Blue - Bishops Hill, Warwickshire 17.05.2014

Male
Photo © Neil Freeman

Small Blue, Male, MHD, 28/07/2014

Male Underside
Photo © Pauline

Small Blue, female, Kithurst Hill, West Sussex, 9 June 2012

Female
Photo © Colin Knight

Small Blue - imago - Martin Down - 31-May-06 (0195)

Female Underside
Photo © Pete Eeles

Photo Album ...


History

The table below shows a chronology of vernacular names attributed to this species. Any qualification of the name (e.g. male, female) is shown in brackets after the name.

YearNameReference
1795Small BlueLewin (1795)
1819Bedford BlueSamouelle (1819)
1853Little BlueMorris (1853)

Conservation Status

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.

UK BAP StatusOccurrence Change
1976-2014 (%)
Abundance Change
1976-2014 (%)
Occurrence Change
2005-2014 (%)
Abundance Change
2005-2014 (%)
Priority Species
Click here to access the Biodiversity Action Plan (BAP) for this species.
Decrease-44
Stable+9
Stable0
Decrease-27

The table above shows the occurrence (distribution) and abundance (population) trends, using information from The State of the UK's Butterflies 2015 (Fox, 2015). Any UK BAP status is taken from the UK Biodiversity Action Plan (UK BAP) (2007 review).

Habitat

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.

Distribution

 

Click here to see the distribution of this species or here to see the distribution of this species together with specific site information overlaid.

Life Cycle

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.

Imago

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.).

Cupido minimus

Small Blue pair - Springhead, Sussex 21-May-2012

Photo © Neil Hulme
21-May-2012

Small Blue, Amberley, 18 May 2009

Photo © Neil Hulme
18-May-2009

Small Blue Female - Addington, Surrey 14-June-10

Photo © Vince Massimo
14-Jun-2010

Small Blue Male - Eyemouth, Scottish Borders - 4-June-2010

Photo © NickMorgan
Scotland

Small Blue Female - Addington, Surrey 14-June-10

Photo © Vince Massimo
14-Jun-2010

Small Blue, male, Kithurst Hill, West Sussex, 22 May 2013

Photo © Colin Knight
22-May-2013

Small Blues - Bishops Hill Warwickshire 26.05.2013

Photo © Neil Freeman
26-May-2013

Small-Blue- 5D31888. Beds, May 2015.

Photo © IainLeach

Small Blue - imago - Martin Down - 22-May-09 (3)

Photo © Pete Eeles
22-May-2009

Small Blue - imago - Martin Down - 22-May-09 (1)

Photo © Pete Eeles
22-May-2009

Small Blue - imago - Martin Down - 21-May-08 (1)

Photo © Pete Eeles
21-May-2008

Small Blue Male (with heavy blue scaling) - Addington, Surrey 1-June-2012

Photo © Vince Massimo
01-Jun-2012

Small Blue - imago - Martin Down - 21-May-08 (2)

Photo © Pete Eeles
21-May-2008

Small Blue male - Bishops Hill Warwickshire 22.05.16

Photo © Neil Freeman
22-May-2016

Small-Blue- 5D32086. Beds, May 2015.

Photo © IainLeach

Small Blue. Prestbury Hill - the masts reserve 16/6/2013

Photo © john starkey

Small Blue - Bishops Hill Warwickshire 26.05.2013

Photo © Neil Freeman
26-May-2013

Small-Blue - Dunstable May 2013 5D33016

Photo © IainLeach

Small-Blue- 5D32035. Beds, May 2015.

Photo © IainLeach

Small Blue males - Brighton, Sussex 8-May-2011

Photo © Neil Hulme
08-May-2011

Photo Album (45 photos) ...


Ovum

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.

"During the process of egg laying the female flies from one flower head of A. vulneraria to another, almost invariably selecting those with fresh, expanding blossoms and generally avoiding those containing withered flowers. Upon settling on a flower head she crawls over the clustered calyces, and curving her abdomen lays a single egg in the hairy covering of the calyx, often between them, apparently laying one egg only on each flower head. But frequently two, three and more eggs may be found on the same flower cluster, which are undoubtedly laid by different parents, and those which have been kept under observation have hatched at different times, proving the eggs were not laid at the same time. Females captured at Purley, Surrey, July 3rd, 1901, deposited many eggs on the 6th, which hatched July 11th, remaining only five days in the egg state ... The eggs are always deposited on the woolly calyces of the blossoms of the kidney vetch (A. vulneraria). The egg is laid singly, embedded among the long cilia of the calyx and attached to it by an ample quantity of gluten. Usually about the middle of the calyx is selected, and most frequently those of the inner flowers, so that the egg is more or less hidden between them. The egg state occupies a period between five and seven days, according to temperature. The egg is very small, measuring only 0.40 mm. in diameter and 0.20 mm. high. In form it more closely resembles that of L. bellargus, but in pattern of reticulations it resembles N. arion. The crown is flattened but not sunken; the micropyle shows a dark central spot. The surface is covered with raised shallow reticulations which form an irregular network pattern over the crown and gradually develop over the side, forming a deep cellular pattern. The cells are irregular but chiefly rhomboidal in shape. The ground colour is a pale blue-green, the reticulations white, which gives the egg a whitish appearance." - Frohawk (1924)

Small Blue - ovum - Martin Down - Unknown Date (2) [Tim Norriss]

Photo © Tim Norriss

Small Blue - ovum - Martin Down - Unknown Date [Tim Norriss]

Photo © Tim Norriss

Small Blue Ovum - Eyemouth, Scottish Borders - May 2010

Photo © NickMorgan

Small Blue - ovum - Solalex, Gryon, Switzerland - 09-Jul-11

Photo © Pete Eeles

Small Blue - ovum - Solalex, Gryon, Switzerland - 09-Jul-11-1

Photo © Pete Eeles

Small Blue - ovum - Solalex, Gryon, Switzerland - 09-Jul-11-8

Photo © Pete Eeles

Small Blue - ovum - Magdalen Hill Down - 26-Jun-12

Photo © Pete Eeles

Small Blue - ovum - Magdalen Hill Down - 26-Jun-12-1

Photo © Pete Eeles

Small Blue ovum - Found at Durdle Door, Dorset - 16.06.14

Photo © Tony Moore
18-Jun-2014

Small Blue ova, Magdalen Hill Down, 27/05/2015

Photo © Pauline
27-May-2015

Small Blue ovum, Magdalen Hill Down, 27/05/2015

Photo © Pauline
27-May-2015

Small Blue - ovum - Magdalen Hill Down - 11-Jun-15-5

Photo © Pete Eeles
11-Jun-2015

Small Blue - ovum - Magdalen Hill Down - 11-Jun-15-6

Photo © Pete Eeles
11-Jun-2015

Small Blue - ovum - Magdalen Hill Down - 11-Jun-15-7

Photo © Pete Eeles
11-Jun-2015

Small Blue - ovum - Magdalen Hill Down - 11-Jun-15-8

Photo © Pete Eeles
11-Jun-2015

Small Blue - ovum - Magdalen Hill Down - 11-Jun-15

Photo © Pete Eeles
11-Jun-2015

Photo Album (16 photos) ...


Larva

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 4 instars in total.

The primary larval foodplant is Kidney Vetch (Anthyllis vulneraria).

Small Blue - larva - Magdalen Hill Down - 11-Jul-12

Photo © Pete Eeles

Small Blue - larva - Magdalen Hill Down - 15-Jul-12

Photo © Pete Eeles

Small Blue - larva - Magdalen Hill Down - 21-Jul-12

Photo © Pete Eeles

Small Blue - larva - Magdalen Hill Down - 10-Jul-15

Photo © Pete Eeles
10-Jul-2015

Small Blue - larva - Magdalen Hill Down - 18-Jul-15

Photo © Pete Eeles
18-Jul-2015

Photo Album (5 photos) ...


1st Instar

"The young larva directly after emergence is very small, only 0.80 mm. long. The head is shining bronze-black. On the first segment is a pale olive-brown dorsal disc, and a smaller darker one on the anal segment. The body is humped dorsally; the lateral lobes somewhat dilated. Along the dorsal surface are two pairs of hairs on each segment, both curving backwards and having tubercular bases; the first is very long, the second short. Above each spiracle are two smaller hairs curving forwards and two lenticles; below the spiracle are three other hairs projecting laterally; all these (seven on each side of a segment) are blackish and very finely serrated and form longitudinal rows, the lateral series forms a fringe surrounding the larva. On the sub-lateral region and claspers are straight, simple, fine hairs. The surface is studded with minute fine black points. The colour of the body is very pale bluish-ochreous, almost white in certain lights and slightly yellowish ventrally. As soon as the larva hatches it eats its way through the calyx to feed on the young green legume within, boring into it. Just before first moult it measures 1.3 mm. long. The ground colour is pale citrine-yellow, checkered with rust-brown arranged in longitudinal rows. The points on the surface are connected by extremely fine stria, forming a very fine delicate network over the body." - Frohawk (1924)

2nd Instar

"After first moult (three days after) it only measures 1.6 mm. long. The ground colour is light citrine-yellow, checkered with dull lilac-red markings, and is more densely studded with hairs than in the previous stage. On the tenth segment is a well developed scent gland, which is kept pulsating while crawling. A few lenticles are dotted over the surface of the body and the dorsal disc on the first segment is olive-brown. The head is shining black, and protruded on a flexible whitish neck while crawling and at times when feeding. The ventral surface is very pale in colour. It continues feeding in the same manner as during the first stage. The black hairs and reddish markings give the larva a deep lilac appearance." - Frohawk (1924)

3rd Instar

"After the second moult it measures 4.2 mm. long while crawling. The ground colour is pale ochreous, with a medio-dorsal dark lilac-brown stripe commencing on the second segment and running to the anal extremity, and three other longitudinal lines of the same colour along the sides above the spiracles; the first is sub-dorsal, narrow and faint, the second is broad and conspicuous and the third is less pronounced; these lines are composed of a series of oblique markings, one on each segment; below the spiracles is a distinct band of the same purplish or lilac-brown colour, which is bordered below by a pale, almost white, lateral line. The ventral surface, including the claspers, is ochreous-yellow; the head and legs shining black. The whole of the surface is densely covered with black serrated bristles of various lengths, each with a pale brownish-amber, fluted, pedestal-shaped base. In the centre of the first segment is a pale shining disc. In this stage they savagely attack and devour each other. Also they readily feed on green peas, boring deeply into them." - Frohawk (1924)

4th Instar

"After the third and last moult, fully grown, the larva measures 9.5 mm. long. The head is very small, black and shining, set on a long retractile neck, which is often considerably protruded while crawling and when at rest is withdrawn under the projecting anterior segment. The body is plump, the segments humped dorsally, but in a less degree than is usual in most Lycanidie larva. The sides are slightly flattened and the lateral ridge rather dilated. There is no dorsal furrow. It is rather densely studded with whitish spinous bristles of various lengths; the longest have pale bulbous bases, the smaller ones being blackish. There are also numerous lenticles sprinkled over the surface. On the tenth segment is a transverse dorsal honey gland, but no retractile tubercles showing. When fully grown the colour varies considerably, but usually the ground colour is pale ochreous. Some are pale primrose-yellow and others very pale greenish. All are more or less marked with pinkish, forming a medio-dorsal longitudinal stripe and two oblique bands on each segment, and a lateral white band edged on each side with pink. In some the pink is hardly perceptible; it is plainest in the greenest forms. The normal period both in a wild state and in captivity for the larva to attain its full growth is about July 20th, when it becomes pale in both ground colour and markings; in some examples the markings are hardly visible. They then prepare for hibernation and spin a few silk strands among the Anthyllis flowers, usually binding three or four of the calyces together and resting between them, forming a slight cocoon (such is the site chosen by almost all the larvae in captivity), and enter into complete hibernation, remaining absolutely motionless for about ten months, i.e., until the beginning of May. They assume exactly the same colouring and bear such remarkable resemblance to the dead calyces that they become practically invisible and form one of the most perfect examples of protective resemblance it is possible to imagine." - Frohawk (1924)

Small Blue - larva - Stockbridge Down - 24-Jul-88 [Tim Norriss]

Photo © Tim Norriss

Small Blue larvae being attended by the ant Lasius niger, near Burnmouth Berwickshire, Scotland. 21st July, 2011.

Photo © IAC

Small Blue larva - Caterham, Surrey 2-Aug-2012 L1

Photo © Vince Massimo
02-Aug-2012

Small Blue larva - Caterham, Surrey 2-Aug-2012 L1

Photo © Vince Massimo
02-Aug-2012

Small Blue larva - Caterham, Surrey 2-Aug-2012 L1

Photo © Vince Massimo
02-Aug-2012

Small Blue larva - Caterham, Surrey 2-Aug-2012 L1

Photo © Vince Massimo
02-Aug-2012

Small Blue larva - Caterham, Surrey 2-Aug-2012 L1

Photo © Vince Massimo
02-Aug-2012

Small Blue (hibernating larva) - Caterham, Surrey 13-Aug-2012 L1

Photo © Vince Massimo
13-Aug-2012

Small Blue (hibernating larva) - Caterham, Surrey 13-Aug-2012 L2

Photo © Vince Massimo
13-Aug-2012

Small Blue (hibernating larva) - Caterham, Surrey 6-March-2013 L2

Photo © Vince Massimo
06-Mar-2013

Small Blue (post-hibernation larva) - Caterham, Surrey 28-May-2013 L2

Photo © Vince Massimo
28-May-2013

Small Blue larva, Magdalen Hill Down, 22/07/2015

Photo © Pauline
22-Jul-2015

Small Blue larva, Magdalen Hill Down, 22/07/2015

Photo © Pauline
22-Jul-2015

Small Blue larva, Magdalen Hill Down, 22/07/2015

Photo © Pauline
22-Jul-2015

Photo Album (14 photos) ...


Pupa

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.

"The pupa measures 8 mm. long and is rather stout in proportion. It bears a close resemblance to a small example of the pupa of N. lucina in its general form, colouring and character of markings. Dorsal view: Head hidden by the slightly projecting pro-thorax, base of wings somewhat swollen, the abdomen rather fullest across the middle, then gradually tapering to the rounded anal segment. Lateral view: Head and pro-thorax rounded, meso-thorax swollen and rounded, slightly sunken at the base of abdomen, which is strongly curved to the rounded anal extremity. The outline of the ventral surface is almost straight. The ground colour is a pale pearly-cream-buff, the head and thorax inclining to livid, and the anal area inclined to flesh colour. Head, thorax and wings speckled and blotched with dusky-brown; on the latter they form stripes between the nervures, mapping out the neuration. A medio-dorsal streak of the same colour runs over the thorax, which is black in front, fading to the meta-thorax; then follows along the abdomen a series of fine medio-dorsal black markings, one on each segment, and a sub-dorsal row of black dots, which are replaced on the thorax by blotches. The ventral surface of the anal segment is furnished with cremastral hooks which are attached to a pad of silk. The abdomen is sparsely speckled with pale brown. The head, thorax and abdomen are clothed with rather long, fine white pectinated bristly hairs, each rising from a swollen disc-like base. The entire surface is covered with fine reticulations. At first the colouring is tinged with greenish over the dorsal area and the wings translucent, which become opaque within twenty-four hours. Excepting the difference in the ground colouring the pupa of Z. minima and C. argiades are almost identical, but the former is without the ciliated hairs on the head. On the seventh abdominal segment of the pupa, a honey gland, apparently analogous to that of the larva, is present in the form of a large, deep and wide incision. The pupa, of which one example has been found in a wild state, is attached head upwards to a blade of grass by a silk cincture and the cremastral hooks firmly fixed into a pad of silk. In captivity an example pupated on the surface of a piece of paper. The pupal stage occupies almost sixteen days." - Frohawk (1924)

Cupido minimus - Pupa [Wolfgang Wagner]

Photo © Wolfgang Wagner
www.pyrgus.de

Small Blue pupa ventral view [Reg Fry]

Photo © Reg Fry

Small Blue pupa lateral view [Reg Fry]

Photo © Reg Fry

Small Blue pupa dorsal view [Reg Fry]

Photo © Reg Fry

Photo Album (4 photos) ...


Aberrations

Description to be completed.

Click here to see the aberration descriptions and images for this species.

Similar Species

Holly Blue

Description to be completed.

Videos


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The following links provide additional information on this butterfly.

References

The species description provided here references the following publications:

ReferenceDetails
Frohawk (1924) Frohawk, F.W. (1924) The Natural History of British Butterflies.
Fuessly (1775) Fuessly, J.K. (1775) Verzeichniss Der Ihm Bekannten Schweizerischen Insekten.
Leach (1815) Leach (1815) In Brewster: The Edinburgh Encyclopaedia.
Lewin (1795) Lewin, W. (1795) The Papilios of Great Britain.
Morris (1853) Morris, Rev.F.O. (1853) A History of British Butterflies.
Samouelle (1819) Samouelle, G. (1819) The Entomologist's Useful Compendium.
Schrank (1801) Schrank, F. (1801) Fauna boica. Durchgedachte Geschichte der in Baiern einheimschen und zahmen Thiere.
Swainson (1827) Swainson, W. (1827) A Sketch of the Natural Affinities of the Lepidoptera Diurna of Latreille. The Philosophical magazine : or Annals of chemistry, mathematics, astronomy, natural history and general science.