CHAPTER XV

_THE HAIRSTREAKS, COPPERS AND BLUES_

Family--LYCAENIDAE

This is a large family, including as it does no less than nineteen of the British species. These are all of small size, and are characterised by their short and jerky flights. They seldom rise much above the ground, and are consequently very easily caught.

The caterpillars of this family have all short and rather thick bodies, shaped very much like that of the wood louse--flattened beneath and very convex above.

The chrysalides are generally attached by the 'tail,' and further secured by a silken cord round the body, as we have already observed in the case of the _Pieridae_.

The perfect insects differ from the preceding species in that all six legs are perfectly developed and adapted for walking.

There are only three genera in this large family:

1. _Thecla_--The Hairstreaks, with 'tailed' wings. 2. _Polyommatus_--The 'Coppers.' 3. _Lycaena_--The 'Blues,' with wings either blue or brown.

_The Brown Hairstreak_ (_Thecla Betulae_)

The five Hairstreaks which constitute the genus _Thecla_ are all pretty insects, characterised by hair-like streaks on the under surface.

_Betulae_ is the largest of these. Its upper surface is of a deep brown colour, with orange-brown marks at the anal angles of the hind wings, and, in the female, a large patch of orange on the fore wings. The under side (Plate VI, fig. 3) is orange brown, much lighter in the male than in the female. On the fore wings are two white lines, the inner one of which is indistinct; and on the hind wings are two others, the outer one being longer and more distinct than the inner.

This butterfly is by no means an abundant insect, though it is widely distributed, and in some places plentiful. Its chief haunts are woods, and we may mention among its favoured localities Epping Forest, Monk's Wood in Cambridgeshire, the wooded parts of South Devon and Dorset, New Forest, Colchester, and Peterborough.

The perfect insect is on the wing from July to October, and the eggs are deposited in the autumn on the twigs of its food plant--the blackthorn (_Prunus spinosa_). These do not hatch till the following spring. Toward the end of June the caterpillar is fully fed.

The colour of the caterpillar is light green, with two white stripes down the back, and two others along the sides. There are also two small oblique whitish lines on each side of each segment.

The chrysalis is smooth, and of a pale brown colour.

_The Black Hairstreak, or White-letter Hairstreak_ (_Thecla W-album_)

The first of the above two popular names has been applied to this species on account of the very deep brown colour of the upper side, which colour is often a near approach to black. The second is due to the W-shaped bend of the white streak of the hind wings. The ground colour of the under side (Plate VI, fig. 4) is greyish brown, with a bright orange band, spotted with black near the hind margin of the hind wings.

_W-album_ is a somewhat rare insect, but is occasionally seen in plenty in a few localities, Cambridgeshire, Berkshire, Epping, Colchester and Suffolk being among its chief resorts. It is out on the wing in July, and should be looked for in wooded country where the common elm (_Ulmus campestris_) and the wych elm (_U. montana_), its food plants, exist.

The eggs are laid on the twigs of these trees late in the summer, and the young caterpillars do not appear till the following spring. The chrysalis may be found attached to an elm twig or leaf about the end of June.

The caterpillar is pale green. The ridges along the back are tinged with yellow, and there are two fine oblique white lines on each side of each segment.

_The Dark Hairstreak_ (_Thecla Pruni_)

The upper side of this butterfly is very much like that of _W-album_, but it may be distinguished by the presence of a few orange spots near the anal angle of the hind wings. The colouring of the under side (Plate VI, fig. 5) is also very similar, except that the white lines of the wings are thinner and less distinct than in the last species, and do not exhibit the W-shaped bend. The orange band of this surface is bordered on each side with a row of black spots, each of which is touched with a bluish white or a metallic blue.

This insect is not by any means common, but has been seen in considerable numbers in certain localities. It is not found in either Scotland or Ireland, and its chief haunts in England seem to be in Huntingdonshire, Cambridgeshire and Northamptonshire. It frequents wooded country, and flies during June and July.

The eggs are laid late in the summer on the twigs of the blackthorn (_Prunus spinosa_), and are not hatched till the following spring.

The caterpillar, which is pale green, with rows of yellow spots, may be found in May.

_The Purple Hairstreak_ (_Thecla Quercus_)

This pretty butterfly, by far the commonest of the Hairstreaks, though comparatively very small, reminds one forcibly of the noble Purple Emperor. Its haunts are the same oak woods, and its upper surface, though only a dull dark brown in certain lights, exhibits the same imperial purple reflections when viewed at certain angles. The purple of the male extends over the whole of the wings, but that of the female is confined to a V-shaped patch at the base of the fore wings. In the latter case, however, the purple is much richer than in the male sex.

The under side (Plate VI, fig. 6) is coloured with a delicate grey ground, adorned with a white streak on each wing, and a couple of orange spots near the anal angle of the hind wings.

This species is very widely distributed, being common in oak woods in most parts of England, and also in many parts of Scotland and Ireland. It flies around the branches of the trees, and often disappoints the collector by keeping far beyond the reach of his net.

Those in search of this pretty insect should ramble in oak woods, preferably in the south of England, during July and August. The eggs may be found glued to the twigs throughout the winter, and the larvae may be beaten from the branches of the oak in June.

The colour of the caterpillar is brownish or pinkish green, with a row of V-shaped marks down the back.

The chrysalis is of a brown colour, short and thick, and may be found either attached to oak leaves, or under the surface of the earth at the foot of the tree on which the caterpillar fed.

_The Green Hairstreak_ (_Thecla Rubi_)

Next to _Quercus_, this is the most plentiful of the genus. It frequents woods and heaths in nearly every county in England, and is also found in parts of Scotland and Ireland. It is peculiar among British butterflies as being the only one that exhibits a bright green colour. It also differs from the other Hairstreaks in two important particulars, for the hind wings, though angled at the hind margin, are not 'tailed,' and the characteristic hairstreak which gives the popular name to the genus is here represented only by a series of white dots across the wings, or, in some cases, by one or two dots on the hind wings only.

The upper side is dark brown, displaying metallic reflections when viewed in a strong light. The under side is represented in fig. 7 of Plate VI.

The chief food plants of this species are the bramble (_Rubus fruticosus_), the birch (_Betula alba_), and the broom (_Cytisus scoparius_).

The perfect insect flies in May and June, and the eggs are deposited during the latter month on the above plants. The caterpillars are full fed in July, and change to the chrysalis state towards the end of the summer.

The colour of the caterpillar is pale green, with a yellow stripe and several white oblique lines along the sides, also a yellowish stripe down the back.

The chrysalis is short and thick, and of a dark brown colour.

_The Large Copper_ (_Polyommatus Dispar_)

Our next genus contains only two British species. The first of these--the Large Copper--was once a common insect at Whittlesea in Cambridgeshire, and in some of the fens of Huntingdonshire, but is now feared to be quite extinct, as none have been seen for many years. The last capture was made in 1847 in Huntingdonshire. However, it _may_ turn up again; and even if it does not, it would be a pity to allow the memory of so fine an insect to die out; so we find room to figure it (Plate VI, fig. 8), and append a few remarks.

There is a very great difference between the male and the female. The former is of a brilliant copper hue, and all the wings have a black margin and a black streak near the middle. The female is larger; and the coppery colour is much redder. The black border of the fore wings is wider, and there are also several large black spots on these wings. The hind wings are almost entirely covered with black, with the exception of a broad coppery band near the hind margin.

The food plant of the caterpillar appears to have been the water dock (_Rumex Hydrolapathum_), on which the eggs were laid late in the summer. It is probable that the caterpillar was a hybernator, seeking its winter shelter while still very young; and it was full fed in June.

Its colour was green, with a darker stripe of the same colour on the back; and the chrysalis was attached by anal hooks and a cord round the body.

_The Small Copper_ (_Polyommatus Phlaeas_)

The only other British member of the genus _Polyommatus_--the Small Copper--is one of the commonest of our butterflies. It may be found in nearly all parts of the British Isles from April to September, more particularly in April, June, _and_ August, for it is apparently triple brooded.

This brilliant and lively little insect is shown on Plate VI (fig. 9), and, being so very familiar, needs no description.

The caterpillar feeds on different species of dock--the broad-leaved dock (_Rumex obtusifolius_), the fiddle dock (_R. pulcher_), the sorrel (_R. acetosa_), and the sheep sorrel (_R. acetosella_); also on the ragwort (_Senecio Jacobaea_). It is full fed about three weeks after hatching, and then changes to a small and stout chrysalis, of a pale brown colour, on the leaf of its food plant.

The caterpillar itself is green, with a reddish line on the back and on each side; and it glides over the surface of the leaves something after the manner of a slug, without exhibiting any very apparent motion of its short legs and claspers.

_The Tailed Blue_ (_Lycaena Baetica_)

We now come to a genus containing no less than ten species of beautiful little butterflies, known commonly as the 'Blues;' but one of them exhibits no trace of the colour so characteristic of the group, although it resembles the others in structure and habits.

Our first example is the Tailed Blue, known also as the Pea-pod Argus. The upper side of this insect (Plate VI, fig. 10) is of a dull smoke colour, exhibiting purple-blue reflections, which are, in the female, confined to distinct blotches on the bases of the wings, but in the male are less noticeable, and extend over the whole surface. The hind margin of the hind wings has a row of spots, more or less distinct, and much more prominent in the female than in the male. The under side is beautifully marked with bands of fawn and grey, and with two spots of brilliant metallic green in the anal angle of the hind wings.

This butterfly abounds in the countries of South Europe, where the caterpillar feeds on the pods of certain leguminous plants; but only a few stragglers have been taken in England, so that its reputation as a true Britisher is very uncertain. It is highly probable that the two or three specimens caught on our south coast were blown over from the Continent, and that the insect has never bred on this side of the Channel.

_The Silver-studded Blue_ (_Lycaena AEgon_)

The upper surface of the male (Plate VI, fig. 11) of this species is purple blue, with a black border on the hind margins of all wings. The female (fig. 12 of the same plate) is of a very dark smoky-brown colour, often with a bluish tinge, and has generally a row of orange spots near the hind margin of the hind wings.

The under side of both sexes is similar, and is illustrated in the accompanying woodcut. The ground colour is bluish grey, and is marked with a number of black spots surrounded by light rings. Along the hind margin of the hind wings is a row of orange spots, each bordered with black on the inner side, and with a silvery blue on the outer.

This insect appears in July, and is common in many dry, sandy, or chalky spots in various parts of England, and also in a few localities in Scotland and Ireland. It has been reported as abundant at Darlington and in certain localities in Lancashire, but its head quarters are undoubtedly the chalk downs and dry gravelly banks of the southern counties.

The caterpillar feeds on the bird's-foot (_Ornithopus perpusillus_), and is full grown towards the end of June. Its colour is yellow or grey, with a brown dorsal stripe, a white line on each side, and pale oblique lines near the former. About the end of June it changes to a dull green chrysalis, with projecting wing cases.

_The Brown Argus_ (_Lycaena Astrarche_)

Neither male nor female of this species exhibits any trace of blue. The upper surface, shown in fig. 13 of Plate VI, is coloured with a warm brown, and all four wings have a row of orange spots near the hind margin. The fore wings have also a central black spot. The under surface, drawn on the same plate (fig. 14), is bluish grey, with a border of orange spots on each hind margin as on the other side. There are also numerous black spots in light rings, the arrangement of which will be seen in the figure.

Some species of butterflies and moths are so variable in their colouring and markings that varieties have often been mistaken for distinct species; and, in other cases, distinct species are sometimes so similar in character that they are looked upon as identical.

A butterfly that closely resembles the normal Brown Argus in many points, and named _Artaxerxes_, has often been described as a distinct species, but is now, I believe, recognised by most entomologists as a constant variety of the present species.

It differs from the normal type in having a _white_ instead of a _black_ spot in the centre of the fore wings, and the border of orange spots is often very indistinct. On the under side, too, instead of black spots in white rings, it has white spots, with little or no trace of a black centre.

The ordinary Brown Argus is a southerner, and is particularly abundant on the chalk downs of the south coast and the Isle of Wight, but _Artaxerxes_ is to be found only in Scotland and the north of England; and it is interesting to note that, between these northern and southern districts, intermediate varieties are to be met with.

Again, _Astrarche_ is a double-brooded butterfly, appearing on the wing in May and August; while _Artaxerxes_ is single brooded, flying at midsummer. This fact has lent support to the opinion that the two are distinct species; but it must be remembered that several insects that are single brooded in one country are double brooded in a warmer climate.

The caterpillar of _Astrarche_ feeds on the hemlock stork's-bill (_Erodium cicutarium_). It is of a pale yellow colour, with a brownish line on the back; and is full fed in April and July.

_The Common Blue_ (_Lycaena Icarus_)

Although this pretty little butterfly is so common that it is almost sure to be known to all who take any interest in insect life, yet it is important to observe it carefully, since it is an easy matter to confound it with other species of the same genus.

The upper surfaces of the two sexes are very different, that of the male (Plate VI, fig. 15) being a beautiful lilac blue; and that of the female (Plate VI, fig. 16) a dark brown, powdered with blue at the bases of the wings, and having _generally_ a border of orange spots, more or less defined, on the hind margins of all wings.

The under side, shown in the accompanying woodcut, is ashy brown; warm in the female, but paler in the male. The hind wings, and sometimes all four, are bordered with orange spots; and this species may be distinguished from _Astrarche_ by the presence of two black spots, in white rings, near the base of the fore wings.

There will be no need to name localities for this insect, as it is abundant everywhere, frequenting meadows, heaths, and all waste places. It is double brooded, and is on the wing continuously from May to September, the first brood enduring from May to July, and the second from July to the end of the warm weather.

The caterpillar is green, with a dorsal line of a darker tint, and a row of white spots on each side. It feeds on clover (_Trifolium pratense_ and _T. repens_), bird's-foot (_Ornithopus perpusillus_), bird's-foot trefoil (_Lotus corniculatus_), and the rest-harrow (_Ononis spinosa_).

The chrysalis is short and rounded, of a dull green colour, tinged with brown on the under surface.

_The Clifden Blue_ (_Lycaena Bellargus_)

Our coloured representations of this beautiful blue (Plate VI, figs. 17 and 18) show that here also there is a great difference between the male and female. The former is a most lovely and brilliant sky blue, bordered by a fine black line; and the latter is a dull dark brown, with a more or less distinct border of orange spots, and the bases of the wings are powdered with scales of a tint corresponding with those of the male. In both sexes the fringe is very distinctly barred with dark brown.

The under side (fig. 90) is similar in both sexes--greyish brown, with a border of reddish spots, and a number of black spots in white rings, the arrangement of which is here represented.

The butterfly frequents chalky downs, chiefly in the south of England, and seems to be unknown in Scotland and Ireland. The Isle of Wight, and the chalky downs and banks of Sussex, Surrey, and Kent, are its favourite localities; and even in these it is generally very local, sometimes swarming on a grassy bank of no great extent, when the surrounding neighbourhood, though apparently equally suitable to its requirements, does not harbour a single specimen. It is on the wing in May and June, and again in August.

The caterpillar is green, with two rows of yellow streaks on the back, and a yellow stripe on each side. It feeds on the Dutch clover (_Trifolium repens_), horse-shoe vetch (_Hippocrepis comosa_), and various other leguminous plants.

_The Chalk-Hill Blue_ (_Lycaena Corydon_)

The male of this species (Plate VII, fig. 1) is readily to be distinguished from all other members of the genus by its pale glossy blue, but the female (fig. 2 of Plate VII) so closely resembles that of _Bellargus_ that it is often a somewhat difficult matter to discriminate between them. The following, however, are a few points worthy of observation: The upper side of the female _Corydon_ has the bases of the wings more or less sprinkled with the pale silky blue that characterises the male; and the black bars of the fringe are _usually_ broader in _Corydon_ than in _Bellargus_. The black-centred spots of the under side are also usually more conspicuous in the former species than in the latter.

The difficulty of identification is increased by the fact that both these butterflies frequent similar localities, and are often on the wing at the same time; but although _Corydon_ is certainly a frequenter of chalky districts, yet it is often found plentifully in districts far removed from the chalk, notably at Arnside in Lancashire, and in Epping Forest.

The butterfly is out in June and July. The caterpillar is green, with two rows of short yellow streaks on the back, and a yellow stripe on each side. It feeds on the purple and Dutch clovers (_Trifolium pratense_ and _T. repens_), bird's-foot trefoil (_Lotus corniculatus_), horse-shoe vetch (_Hippocrepis comosa_), and lady's fingers (_Anthyllis vulneraria_).

_The Holly Blue_ (_Lycaena Argiolus_)

While all the other Blues delight to sport on low flowery banks in the full blaze of the summer's sun, the Holly Blue prefers to flit among the branches of trees, often many feet from the ground. The larva feeds on the flowers of the holly (_Ilex Aquifolium_) in the spring, and on those of the ivy (_Hedera Helix_) late in the summer; also on the alder buckthorn (_Rhamnus Frangula_); and it is in localities where these grow that we may find this lovely Blue sporting among the branches, or resting on a leaf with its wings folded together, thus making itself conspicuous among the dark foliage by exposing the pale silvery blue of its under surface.

The upper sides of both the male and female are shown on Plate VII (figs. 3 and 4 respectively), where the beautiful lilac blue will be seen to have a border of black, wider in the latter than in the former.

The under surface is spotted with black, as shown in fig. 92, and has no border of orange spots.

This is a double-brooded butterfly, appearing first in April and May, and then again in August. It is not at all uncommon in the south of England, and extends northward as far as the Lake District, but is not found in Scotland. It is generally distributed throughout Ireland.

The caterpillar may be looked for in June and October. It is light green, with a line of dark green down the back.

_The Mazarine Blue_ (_Lycaena Semiargus_)

The male (Plate VII, fig. 5) is deep purple blue, with a narrow dark-brown border, and the female (fig. 6 of the same plate) dark brown. The under side of both sexes is light greyish-brown or drab, with a row of black spots in white rings parallel with the hind margin of each wing, and no reddish or orange spots.

This pretty butterfly seems to have been plentiful in several localities some years since, but has not been seen for a long time; and it is probable that its reckless slaughter by those who catch all the pretty butterflies they can secure either for ornament or for gain has caused its name to be permanently removed from our list of natives.

It was formerly abundant in Dorset, Hereford, Glamorganshire, and near Shirley, and was on the wing in June and July, but it disappeared from our view before a full account of its life history had been prepared.

_The Small Blue_ (_Lycaena Minima_)

We now come to the smallest of all British butterflies--a little insect that measures less than one inch from tip to tip when its wings are expanded. Its upper surface is of a dull and dark-brown colour, the bases of the wings being dusted with blue in the case of the male. The under side is pale drab, tinged with greenish blue at the bases of the wings, and marked with black spots in light rings as shown in the accompanying figure. The upper side is represented in fig. 7 of Plate VII.

This butterfly is on the wing in May and June, and during the latter month the eggs are deposited on the flowers of the lady's fingers (_Anthyllis vulneraria_).

The caterpillars are hatched in about a week, and commence feeding on the calyx of the buds, and soon burrow into them till they are quite concealed.

The colour of the caterpillar is brownish, with a darker stripe on the back, and a row of oblique brown streaks on each side.

This species is widely distributed in England, and is plentiful in most chalky and limestone districts. It is also found in parts of Scotland and Ireland.

_The Large Blue_ (_Lycaena Arion_)

The last of our Blues is the largest of the genus, and is, with the exception of _Semiargus_, the rarest. It is a very local insect, appearing in small numbers, during June and July, in parts of South Devon, Gloucestershire, Northamptonshire, and a few other counties.

The colour of the upper side is a dark and rich blue, with a broad dark border on the hind margins, and a group of black spots near the centre of the fore wings. The under side (fig. 95) is of a pearly grey, without any red spots, but having a double border of black spots, and also an irregular row of black spots in white rings across the middle of each wing.

The caterpillar feeds on thyme (_Thymus Serpyllum_), on which plant the eggs are laid singly, generally on the flower heads.