CHAPTER XII

_THE SWALLOW-TAIL AND THE 'WHITES'_

Family--PAPILIONIDAE

_The Swallow-tail_ (_Papilio Machaon_)

Our first family (_Papilionidae_) contains only one British species--the beautiful Swallow-tail (_Papilio Machaon_), distinguished at once from all other British butterflies by its superior size and the 'tails' projecting from the hind margin of the hind wings.

This beautiful insect is figured on Plate I, where its bold black markings on a yellow ground are so conspicuous as to render a written description superfluous. Attention may be called, however, to the yellow scales that dot the dark bands and blotches, making them look as if they had been powdered; also to the blue clouds that relieve the black bands of the hind wings, and the round reddish orange spot at the anal angle of each of the same wings.

It appears that this butterfly was once widely distributed throughout England, having been recorded as common in various counties, and has also been taken in Scotland and Ireland; but it is now almost exclusively confined to the fens of Cambridgeshire, Huntingdonshire, and Norfolk. Occasionally we hear of the capture of single specimens quite outside these localities, sometimes even in most unlikely spots, where its food plant does not abound. But we know that _Machaon_ is a general favourite with entomologists, and that it is sent in the pupal state, by post, to all parts of the kingdom; so that the occasional capture of the insect far beyond the borders of its haunts is probably the outcome of an escape from prison, or of the tender-heartedness of some lover of nature who could not bear to see such a beautiful creature deprived of its short but joyous, sunny flight.

You cannot hope to see this splendid butterfly on the wing unless you visit its haunts during its season--May to August; but the pupae may be purchased for a few pence each from most of the entomological dealers; and if you obtain a few of these and watch them closely, you may be fortunate enough to see the perfect insect emerge from its case, and witness the gradual expansion of its beautiful wings.

The pupa (Plate VIII, fig. 7) itself is a most beautiful object. Its colour is a pale green, and it is fixed to its support by the tail, and further secured by a very strong silk band.

The larva (Plate VIII, fig. 1), too, is exceedingly beautiful. Its ground colour is a lovely green, and twelve velvety black rings mark the divisions between the segments. Between these are also black bars, all spotted with bright orange except the one on the second segment.

A remarkable feature of this larva is the possession of a forked, Y-shaped 'horn,' that is projected from the back, just behind the head, when the creature is alarmed. If it is gently pressed or irritated in any way, this horn is thrust out just as if it were an important weapon of defence. And perhaps it is, for it is the source of a powerful odour of fennel--one of the food plants of the caterpillar--that may possibly prove objectionable to some of its numerous enemies.

The food plants of _Machaon_ are the milk parsley or hog's fennel (_Peucedanum palustre_), cow-parsnip (_Heracleum sphondylium_), and the wild angelica (_Angelica sylvestris_); but in confinement it will also partake of rue and carrot leaves.

The caterpillar of this species may be found in the fens during the greater part of the summer. It turns to a chrysalis in the autumn, and remains in this state throughout the winter, attached to the stems of reeds in the vicinity of its food plants. The perfect insect is first seen in May, and is more or less abundant from this time to the month of August.

Family--PIERIDAE

This family, though known commonly as the 'Whites,' contains four British species that display beautiful tints of bright yellow or orange.

In many respects the _Pieridae_ resemble the last species. Thus the perfect insects have six fully developed legs; the caterpillars are devoid of bristles or spines; and the chrysalides are attached by means of silky webs at the 'tails,' and strong cords of the same material round the middle.

All the larvae are also cylindrical or wormlike in shape; and their skins are either quite smooth, or are covered with very short and fine hairs, that sometimes impart a soft, velvety appearance.

The members of this family are remarkable for their partiality for certain of our cultivated plants and trees; and are, in some cases, so abundant and so voracious, that they are exceedingly destructive to certain crops.

_The Black-veined White_ (_Aporia Crataegi_)

This butterfly may now be regarded as one of our rarities. At one time it was rather abundant in certain localities in England, among which may be mentioned the neighbourhoods of Cardiff and Stroud, also parts of Kent, Sussex, Hampshire, Huntingdonshire, and the Isle of Thanet; but it is to be feared that this species is nearly or quite extinct in this country. It is well, however, not to give up the search for it, and if you happen to be in one of its favoured localities of former days, you might net all the doubtful 'Whites' of large size that arouse your suspicions, liberating them again if, on inspection, they do not answer to the description of the species 'wanted.' This course becomes absolutely necessary, since the Black-veined White is hardly to be distinguished from the Common Large White while on the wing.

If you examine a number of British butterflies you will observe that in nearly all species the wings are bordered by a fringe of hair, more or less distinct. But the case is different with _Crataegi_. Here they are bordered by a black nervure, without any trace of fringe, thus giving an amount of rigidity to the edges (see Plate I, fig. 2).

The wing rays, or nervures, are very distinct--a feature that gave rise to the popular name of the butterfly. In the male they are quite or nearly black, but those of the fore wings of the female are decidedly brown in colour. At the terminations of the wing rays there are triangular patches of dark scales, the bases of which unite on the outer margins of the wings.

Another peculiar feature of this insect is the scanty distribution of scales on the wings. This is particularly so in the case of the female, whose wings are semi-transparent in consequence.

The butterfly is on the wing during June and July, at which time its eggs are laid on the hawthorn (_Crataegus Oxyacantha_) or on fruit trees--apple, pear and plum.

A vigorous search of these trees in the proper localities _may_ reveal to you a nest of the gregarious larvae, all resting under the cover of a common web of silk. These remain thus under their silken tent throughout the hottest hours of the day, and venture out to feed only during the early morning and in the evening.

When the leaves begin to fall in the autumn, they construct a more substantial web to protect themselves from the dangers of the winter, and in this they hybernate till the buds burst in the following spring. They now venture out, at first during the mildest days only, and feed voraciously on the young leaves, returning to their homes to rest. Soon, however, they gradually lose their social tendencies, till at last, when about half or three-quarters fed, they become quite solitary in their habits.

In May they are fully grown, and change to the chrysalis state on the twigs of their food trees.

The larva is black above, with two reddish stripes. The sides and under surface are grey, the former being relieved by black spiracles.

The pupa (page 45) is greenish or yellowish white, striped with bright yellow, and spotted with black.

It is probable that the reader will never meet with this insect in any of its stages. But, though it may have left us, it is still very abundant on the Continent, where it does great damage to fruit trees; and the foreign pupae may be purchased of English dealers.

_The Large White_ (_Pieris Brassicae_)

We pass now from one of the rarest to one of the most abundant of British butterflies. Everybody has seen the 'Large White,' though we doubt whether everybody knows that this insect is not of the same species as the two other very common 'Whites.' The three--Large, Small, and Green-veined--are so much alike in general colour and markings, and so similar in their habits and in the selection of their food plants, that the non-entomological, not knowing that insects do not grow in their perfect state, may perhaps regard the larger and the smaller as older and younger members of the same species. But no--they are three distinct species, exhibiting to a careful observer many important marks by which each may be known from the other two.

On Plate I (fig. 3) will be seen a picture of the female _Brassicae_, in which the following markings are depicted: On each fore wing--a blotch at the tip, a round spot near the centre, another round one nearer the inner margin, and a tapering spot on the inner margin with its point toward the base of the wing. On the hind wings there is only one spot, situated near the middle of the costal margin.

The male may be readily distinguished by the absence of the black markings on the fore wings, with the exception of those at the tips. He is also a trifle smaller than his mate.

This butterfly is double-brooded. The first brood appears in April and May, the second in July and August; and the former--the spring brood--which emerges from the chrysalides that have hybernated during the winter, have _grey_ rather than black tips to the front wings.

The ova of _Brassicae_ may be found on the leaves of cabbages in every kitchen garden, also on the nasturtium, during May and July. They are pretty objects (see fig. 10), something like little bottles or sculptured vases standing on end, and are arranged either singly or in little groups.

As soon as the young larvae are out--from ten to fifteen days after the eggs are deposited--having devoured their shells, they start feeding on the selfsame spot, and afterwards wander about, dealing out destruction as they go, till little remains of their food plant save the mere stumps and skeletons of the leaves.

The ground colour of the caterpillar is bluish green. It has a narrow yellow stripe down the middle of the back, and two similar but wider stripes along the sides; and the surface of the body is rendered somewhat rough by a number of small black warty projections, from each of which arises a short hair.

When fully grown, it creeps to some neighbouring wall or fence, up which it climbs till it reaches a sheltering ledge. Here it constructs its web and silken cord as already described (page 36), and then changes to a bluish-white chrysalis, dotted with black. The butterflies of the summer brood emerge shortly after, but the chrysalides of the next brood hybernate till the following spring.

It is remarkable that we are so plagued with 'Whites' seeing that they have so many enemies. Many of the insect-feeding birds commit fearful havoc among their larvae, and often chase the perfect insects on the wing, but perhaps their greatest enemy is the ichneumon fly.

Look under the ledges of a wall of any kitchen garden, and you will see little clusters of oval bodies of a bright yellow colour. Most gardeners know that these are in some way or other connected with the caterpillars that do so much damage to their vegetables. They are often considered to be eggs laid by the larvae, and are consequently killed out of pure revenge, or with a desire to save the crops from the future marauders.

No greater mistake could be made. These yellow bodies are the silken cocoons of the caterpillar's own foes. They contain the pupae of the little flies whose larvae have lived within the body of an unfortunate grub, and, having flourished to perfection at the expense of their host, left its almost empty and nearly lifeless carcase to die and drop to the ground just at the time when it ought to be working out its final changes. Often you may see the dying grub beside the cluster of cocoons just constructed by its deadly enemies. Should you wish to test the extent of the destructive work of these busy flies, go into your garden and collect a number of larvae, and endeavour to rear them under cover. The probability is that only a small proportion will ever reach the final state, the others having been fatally 'stung' before you took them.

_The Small White_ (_P. Rapae_)

This butterfly closely resembles the last species except in point of size. The male, represented on Plate I (fig. 4), has a dark grey blotch at the tip of each fore wing, a round spot of the same colour beyond the centre of that wing, and another on the costal margin of the hind wing. The female may be distinguished by an additional spot near the anal angle of the fore wing.

Although this and the two other common butterflies (_Brassicae_ and _Napi_) that frequent our kitchen gardens are usually spoken of as 'Whites,' a glance at a few specimens will show that they are not really white at all, but exhibit delicate shades of cream and yellow, inclining sometimes to buff. The under surfaces are particularly noticeable in this respect, for here the hind wings and the tips of the fore wings display a very rich yellow.

The species we are now considering is also very variable both in its ground colour and the markings of the wings. The former is in some cases a really brilliant yellow; and the latter are in some cases entirely wanting.

_Rapae_ is double-brooded, the first brood appearing in April and May, and the other in July and August.

During these months the eggs may be seen in plenty on its numerous food plants, which include the cabbages and horse-radish of our gardens, also water-cress (_Nasturtium officinale_), rape (_Brassica Napus_), wild mustard (_B. Sinapis_), wild mignonette (_Reseda lutea_), and nasturtium (_Tropaeolum majus_).

The eggs are conical in form--something like a sugar loaf, with ridges running from apex to base, and very delicate lines from ridge to ridge transversely.

The young larvae often make their first meal of the shell, and then attack the food plant so voraciously that they are fully grown in about three or four weeks. In colour they are of a beautiful glaucous green, hardly distinguishable at times from the leaves on which they rest. A yellow stripe runs along the middle of the back, and lines of yellow spots adorn the sides; and the whole body is covered with very short hairs, each one arising from a minute warty projection.

The pupae may be found during the same seasons and in the same situations as those of _Brassicae_. They are very variable in colour. Some are of a very pale grey or putty colour, some are decidedly brown, and others of a greenish tinge; and they are often spotted and striped with dark grey or black.

_The Green-veined White_ (_P. Napi_)

A non-observant beginner at entomological work may easily mistake this insect for the last species, for the ground colour and markings are very similar, even to the features by which the sexes are distinguished from each other; but an inspection of the under surface will give a ready means of identification, for here the wing rays are bordered with black scales which, by contrast with the rich yellow around them, often appear of a greenish hue. The butterfly receives its popular name from this circumstance.

A careful observer, however, will readily find distinguishing marks on the upper side, for here also the chief 'veins' are more or less accompanied with black scales, especially the extremities of those of the fore wings, where little triangular blotches are often distinctly formed; and the dark veining of the under surface of the hind wings frequently shows through. The under side of this insect is shown on Plate I (fig. 5).

This butterfly is not so abundant as the two preceding, but is widely distributed throughout England, and is in most parts decidedly plentiful.

The first brood (for it also is double-brooded) appears during April and May, and the second in July and August.

The eggs are very similar to those of _Rapae_, resembling ribbed and striated sugar loaves; and the larvae are of the same rich glaucous green, but may be identified by the black spiracles surrounded by yellow rings. In our gardens we may find both eggs and larvae on mignonette and horse-radish; the other food plants of this species include the water-cress (_Nasturtium officinale_), winter cress (_Barbarea vulgaris_), rape (_Brassica Napus_), cuckoo-flower (_Cardamine pratensis_), and Jack-by-the-hedge (_Sisymbrium Alliaria_).

The pupa is greenish, and marked with small black dots.

_The Bath or Green-chequered White_ (_P. Daplidice_)

There is no doubt that many butterflies migrate from one country to another across the seas; and as the Bath White is very common on the other side of the Channel, and has been taken very sparingly in England almost exclusively in the south-east, it is highly probable that the majority of those that have been captured here are specimens that have taken a voluntary trip across the water, or have been blown over during rough weather.

This butterfly is one of our greatest rarities, and the capture of a specimen in England is an event that must necessarily be recorded in our entomological literature. It seems that _Daplidice_ has bred in England, for its caterpillars have been found at large on one or two occasions, so I will give a short description of the various stages of the insect, with a hope that some of my readers may be fortunate enough to meet with it.

The female butterfly is shown on Plate I, fig. 6. From this it will be observed that each of the fore wings is tipped with a rather large smoky-black blotch, in which are four white spots. A double spot of the same colour also occupies a place near the centre of the wing, and another smaller and round one lies near the anal angle. The hind wings are clouded with grey, and bordered along the hind margin with distinct smoky-black spots.

The male may be distinguished from the female by the absence of the spot near the anal angle of the fore wings, and of all the clouds and spots of the hind wings. Nevertheless the latter have a decidedly clouded appearance, but this is due to the markings of the under surface showing through them.

The under side of both sexes is most beautifully marked--the fore wings resembling the upper sides, but the hind pair chequered with a beautiful soft green on a pale yellow ground.

The eggs of this insect are deposited during April and May, and again in August or September--for it is, like the other 'Whites,' double-brooded--on two species of Wild Mignonette (_Reseda lutea_ and _R. luteola_).

The caterpillars, which are of a bluish colour, with two yellow stripes down the back, and two others along the sides, may be _looked_ for in June and September. Those of the first brood only have been taken in this country, while the others on the Continent change to the chrysalis in the autumn, and hybernate in this state throughout the winter.

The chrysalis is of a brownish colour, and closely resembles that of the Small White in form.

Those in search of this rare British insect should wander along the south-east coast, and net all the doubtful slow-flying small Whites (_Daplidice_ is rather slow and heavy on the wing), and their perseverance _may_ be rewarded with a prize that will ever be a reminder of a glorious catch and an eventful day. If you fail in this, and most probably you will, rather than remain a stranger to this beautiful and interesting insect, fill up the blank in your cabinet with a foreign specimen, which can be obtained at any time for a few pence, but be careful to label it 'not British,' in order that your brother collectors may not be deceived, or be led to make any unnecessary inquiries.

_The Orange Tip_ (_Euchlo[:e] Cardamines_)

No one could possibly mistake the male of this species for any other British butterfly, the popular name alone giving quite sufficient information for its identification, but the female Orange Tip is _not_ tipped with orange, and its markings, both above and beneath, resemble those of _Daplidice_ so nearly that the same written description might apply almost equally well to both.

On Plate I (fig. 7) is shown the upper side of the male, and just opposite it (fig. 8) the under surface of the same. The female is usually a little larger than her mate, and is marked similarly on both sides except that the bright orange blotch is entirely wanting. She may always be distinguished from _Daplidice_ by the smaller size of the white spots that break the dark blotch at the tip of the fore wing; also by the very small size of the dark spot in the centre of the same wing. The green chequerings of the under side of the hind wings are also more sharply defined, and the insect is generally of a lighter build.

Like many other butterflies, the Orange Tip is subject to variations in colouring. Sometimes a pale but bright yellow takes the place of the white ground, and the orange blotch of the male is occasionally present on the upper or lower surface only.

_Cardamines_ is a single-brooded insect, and is essentially a creature of the spring, at which time it may be found in abundance in lanes, meadows, and clearings in woods throughout the British Isles. Its flight is so light and airy that even the female may easily be distinguished from other Whites when on the wing, while the brilliant orange of the male, intensified by the bright rays of the spring sun, may be identified at some considerable distance.

The food plants of _Cardamines_ include the cuckoo-flower (_Cardamine pratensis_) and the bitter cress (_C. impatiens_), after which the insect is named, also water-cress (_Nasturtium officinale_), winter cress (_Barbarea vulgaris_), rock cress (_Arabis perfoliata_), hedge mustard (_Sisymbrium officinale_), Jack-by-the-hedge (_S. Alliaria_), wild mustard (_Brassica Sinapis_), &c., and the eggs of the butterfly may be found on these during May and June.

The caterpillar (Plate VIII, fig. 2) is green, with a white stripe on each side, and its body is covered with short hair. In July it is fully grown, and ascends a stem of the food plant to prepare itself for its long winter sleep.

The chrysalis (Plate VIII, fig. 8) is a very peculiar object. Both ends are much elongated and sharply pointed; and the foremost extremity stands out at an angle with the stem to which it is attached.

This butterfly should be looked for during April and May, but in mild seasons it may often be met with in March.

_The Wood White_ (_Leucophasia Sinapis_)

The distinguishing feature of this butterfly (see Plate II, fig. 1) is the extreme lightness and delicacy of its build. Its wings are narrow, and rounded at the tips; and the only mark to relieve the white ground of the upper side is a squarish blotch at the tip of the fore wing, and even this is either very indistinct or entirely absent in the female. The under surface is clouded with a pale greenish tint.

This insect may be looked for in May and again in August, in paths and clearings in woods, where it moves along with a slow but steady flight, hardly ever seeming to rest for a moment. It is not by any means a common butterfly, but is very widely distributed, and sometimes appears in considerable numbers in certain favoured spots. Among the localities recorded may be mentioned Torquay, Exeter, Plymouth, South Dorset, New Forest, Reading, Darent Woods, Morecambe Bay, Haslemere, Windermere, &c.

The caterpillar is of a beautiful green colour, and is covered with short whitish hairs. A darker green stripe runs down the middle of the back, and a bright yellow stripe along each side. Its food plants are the tufted vetch (_Vicia Cracca_), bird's-foot trefoil (_Lotus corniculatus_ and _L. pilosus_), bitter vetch (_Lathyrus tuberosus_), and the everlasting pea (_L. sylvestris_).

The chrysalis is a very beautiful object. Its colour is a delicate green, tinged with pink; and the wing-cases project in beautiful curves much beyond the general surface.

_The Pale Clouded Yellow_ (_Colias Hyale_)

The ground colour of this butterfly (Plate II, fig. 2) is very variable. It is usually a sulphury yellow, and on this account the insect is commonly known as the Clouded Brimstone; but sometimes the yellow is exceedingly pale--almost white--and tinged with green.

A very large black blotch, broken by indefinite patches of the ground colour, fills up the tip of each fore wing, and extends to the anal angle, becoming narrower as it approaches this point. A black oval spot lies just above the middle of this wing.

The hind wings are bordered with black, and a conspicuous spot of deep yellow lies very near the centre of each.

The antennae are rather short, compared with those of the preceding members of this family, and are distinguished by their reddish-brown colour.

The male and female of this species are similarly marked, but the ground colour of the latter is commonly paler.

This is not by any means a very common butterfly with us, though it is very plentiful on the other side of the Channel; but it has a way of taking us by surprise in certain seasons, and then almost neglecting us for several years together.

Its head quarters are certainly the coasts of Kent and Sussex, but it has been taken in considerable numbers as far west as Cornwall, and also to a less extent in some of the midland and northern counties. It is particularly fond of lucerne and clover fields, especially those that are situated close to the sea cliffs; and often it may be seen flying over the beach, sometimes even flitting over the breakers away from land till at last it disappears in the distance. This maritime tendency of _Hyale_ makes it probable that a large number of those that are seen on our south-east coasts have made a passage across the narrow end of the Channel.

The eggs are laid in spring, by females that have hybernated throughout the winter, on various leguminous plants, including the lucerne (_Medicago sativa_), black medick (_M. lupulina_), purple and Dutch clovers (_Trifolium pratense_ and _T. repens_), and the bird's-foot trefoil (_Lotus corniculatus_), and on these plants you may search for the larva, though it can scarcely be said that you are likely to find it.

The caterpillar is green, with black dots, and a yellowish stripe on each side. When fully grown it ascends a stem of its food plant and changes to a green chrysalis with yellow stripes.

_Hyale_ is single-brooded in England, although two broods regularly appear on the Continent. In our country the perfect insects emerge during July and August. Many of these die before the approach of winter; but, as we have already observed, some hybernate and deposit their eggs in the following spring.

_The Clouded Yellow_ (_Colias Edusa_)

Not only are this and the last species similarly named, but a glance at the figures will show that they much resemble each other in appearance; and we shall also learn presently that in their habits and life history they have much in common.

The male _Edusa_ is shown on Plate II (fig. 3), and when we compare it with its relative on the opposite side, we are at once struck with the superior richness of the brilliant orange or saffron of the ground colour. The black border of both fore and hind wings is also denser, wider, and more extensive. The whole of the yellow area of the hind wings is dusted more or less with black scales, with the exception of a round central spot of deep orange, corresponding with the orange spots on the hind wings of _Hyale_.

The female, which is shown in the accompanying woodcut, is generally larger than the male, and is further distinguished by the very pale yellow spots that break the black border of both pairs of wings.

_Edusa_ further resembles _Hyale_ in the reddish colour of the antennae; and, in both the species, the red legs form a pleasing contrast with the yellow furry surface of the under side of the thorax.

There is a variety of the female of this butterfly, in which the ground colour is a _very pale_ yellow, almost white. The hind wings are more thickly dusted with black scales than in the normal insect, and the orange spots of these wings show up much more conspicuously from the contrast with their surroundings.

It is usual to apply distinct names to constant varieties of species--names that are to be added to the ordinary title. In this particular case the distinguishing name is _Helice_, so that we should speak of the variety of _Edusa_ above mentioned as:

_Colias Edusa_, var. _Helice_

Like _Hyale_, _Edusa_ is particularly capricious in its appearance. In certain summers it absolutely swarms in favourite localities, while during the intervals between such remarkable appearances--usually several years--it is positively scarce. The last favoured season was the summer of '92, during which (from the beginning of August to the end of the summer) dozens might easily have been caught in an hour or two; in fact, so plentiful were they in many places, that they were continuously in sight, often several at one time.

Those in search of this insect should repair to the south coast, especially the south-east, and where lucerne and clover fields are in flower. It has very decided maritime tendencies, and may often be seen flying over the cliffs and beaches, and even skipping over the breakers; but, at the same time, it is more or less plentiful in many inland districts. It has been taken in many parts of Ireland and Scotland, particularly along the southern coasts of these countries; but its head quarters are undoubtedly the southern cliffs of England, from Cornwall to Kent, and also the hilly inland districts of the south-eastern counties.

_Edusa_ catching is very lively sport, and is likely to prove sufficient for any lover of outdoor exercise under a scorching sun; for this butterfly is not only very powerful on the wing, but its flights are usually long, so that a good run is often absolutely necessary in order to capture it. On very hilly ground, such as _Edusa_ loves, chase is often hopeless, and then it is necessary to resort to stratagem. In such a case the best plan is to make a very cautious approach when the insect has been observed to settle, and then secure it with a sudden down-stroke of the net.

The eggs are laid during May and June by a few females that have survived the winter.

The caterpillar may be found in June and July on its food plants, the chief of which are the bird's-foot trefoil (_Lotus corniculatus_), and the purple and Dutch clovers (_Trifolium pratense_ and _T. repens_). Its colour is grass-green, and it is marked with a narrow whitish stripe on each side, which is broken by the yellow of the spiracles.

The chrysalis is of a pale yellowish green, and is marked with yellow stripes and reddish-brown dots.

_The Brimstone_ (_Gonopteryx Rhamni_)

This, the last member of the present family, is remarkable for the graceful outline of its wings. The costal margins of the fore pair are most beautifully arched, and both pairs are sharply angled on the hind margins. This latter characteristic is quite unique among British butterflies, though we shall presently meet with instances of angular projections on hind wings only.

The ground colour of the male (Plate II, fig. 4) is a rich sulphury yellow, with a greenish tinge. That of the female is a very pale greenish yellow. The only conspicuous markings are small saffron spots, one near the centre of each wing. The antennae are red, short, and beautifully curved; but, unlike the two preceding species, the legs are almost white.

The eggs of this butterfly are laid in April on the two species of buckthorn (_Rhamnus catharticus_ and _R. Frangula_) by the females that have successfully weathered the winter. They are of a bright yellow colour, and are usually hatched in about a fortnight.

The body of the caterpillar is green, and it is thickly covered with little black wart-like projections. A pale stripe also runs along each side. During May and June it may be found on its food plants, and toward the end of the latter month it attaches itself by a silken carpet and belt to the under side of one of the leaves.

The chrysalis is of a very peculiar shape, the body being curved, and the wing cases standing out prominently beyond the general surface. Its colour is a bright apple green marked with yellow, and it is so transparent that certain of the structures can be seen through its skin.

The perfect insect emerges in about three weeks after the change to the chrysalis; and may be looked for from July to the end of the summer. This period may be regarded as the best time in which to hunt for _Rhamni_, but it is to be noted that this butterfly makes its appearance during all months of the year, even though it is single-brooded.

A large number seem to hybernate, and their winter sleep is so light that the welcome rays of the sun on a mild day, even during the bleak months of November to February, will often call them out from their hiding places. Then, as a rule, the hybernating butterflies do not live long after depositing their eggs for the future brood; but the Brimstone often lives on till its offspring have themselves attained the perfect state, so that it is possible to capture the insects of two different years both on the same day. In such a case it is generally easy to distinguish between the two, for the newly emerged specimens are beautifully bright and fresh in colour, while those of the previous year are more or less faded and worn, their wings being often semi-transparent through the loss of scales, and frequently disfigured by the stains of mildew.