CHAPTER XVII

_SPHINGES_

We have already observed the chief features by which we are able to distinguish between butterflies and moths (page 56), so we shall devote the present division to a description of the characteristics and life histories of some of the latter insects.

The number of British butterflies is so limited that space could be found for a brief description of every species, but with moths the case is very different. There are about two thousand known British species of this division of the Lepidoptera, and every year adds some newly discovered insects to this long list; we shall therefore have to content ourselves with making a selection of these for individual mention.

In doing this I shall endeavour to provide the young entomologist with a fairly representative list--one that will enable him to become more or less intimately acquainted with all the principal divisions of the _Heterocera_; and his attention will be drawn especially to many which may be described as 'common' or 'generally distributed,' so that during his first few seasons at collecting he may be enabled to identify and study a fair proportion of his captures. Occasionally, however, one of the rarer species will be described in order to illustrate some striking characteristic.

We shall commence with the tribe of _Sphinges_ or _Hawk Moths_.

This group consists of three families--the _Sphingidae_, including the largest of the 'Hawks,' and the 'Bee Hawks,' the _Sesiidae_ or 'Clearwings,' and the _Zygaenidae_, including the 'Foresters' and the 'Burnets'--numbering in all about forty species.

Family--SPHINGIDAE

This family is named from a fancied resemblance of the larvae to the celebrated Egyptian sphinx. The perfect insects have very thick bodies, generally tapering toward the tail, and their wings are rather narrow in proportion to the length, but are exceedingly powerful, and the flight is, with one or two exceptions, very rapid. The antennae terminate in a small and thin hook.

Most of these insects fly at dusk, but a few delight in the brightness and heat of the midday sun. In either case the velocity of their flight is generally so great that it is a difficult matter to follow them with the eye, and a still more difficult matter to secure the insects in the net; consequently, the best way to study them is to search out the larvae on their food plants, and rear them till they attain their perfect form.

The larvae of the _Sphingidae_ are large and smooth, and most of them have a horn projecting from the top of the last segment but one. They all undergo their metamorphoses under the surface of the ground.

_The Death's-Head Hawk_ (_Acherontia Atropos_)

Our first example of the Sphinges is the beautiful Death's-Head Hawk Moth--an insect that often attains a breadth of five inches from tip to tip when the wings are fully expanded. Its popular title has been applied on account of the peculiar markings of the thorax, which are said to resemble a human skull; and this feature has certainly some connection with the superstitious beliefs of ignorant country folk concerning this moth. But this characteristic is probably not the only one that has caused the creature to be regarded with superstitious alarm. Both its superior dimensions and nocturnal habits serve to intensify the unfounded fear; but, what is particularly striking and unique about it is its power of uttering a squeaking sound, which it does when disturbed. Even the earlier stages of the insect possess this strange power. The caterpillar makes a peculiar snapping noise when irritated, and the chrysalis has been observed to squeak shortly before the emergence of the perfect form.

The fore wings of this moth are of a very rich dark brown, beautifully mottled with lighter tawny shades, and with a small but conspicuous yellow dot near the centre. The hind wings are yellow, with a black band and margin; and the body is yellow, with six broad black bands, and six large blue spots down the middle.

The moth is rather widely distributed, and even common in some parts, but is not nearly so often met with as the larva. It is on the wing during August and September.

It is probable that the reader will never have an opportunity of capturing the perfect form of this remarkable species, but he may with a little perseverance obtain some caterpillars and rear them. These larvae feed on the potato, the deadly nightshade (_Atropa Belladonna_), and the woody nightshade (_Solanum Dulcamara_); and they are well known to potato growers in some parts of the country.

The colour of the caterpillar is generally pale yellow, with numerous small black dots, and seven oblique violet stripes on each side. The horn is yellowish and rough, and is bent downward, but recurved again at the tip.

It feeds during the night, and remains hidden throughout the daytime. In August it is fully grown, and then retires into the ground to undergo its transformations.

_The Privet Hawk_ (_Sphinx Ligustri_)

This is another fine moth, measuring nearly four and a half inches from tip to tip. It is represented in the centre of Plate IX in its natural colours, so that it need not be described.

The perfect insect flies in June and July, and, although common, is not frequently seen at large. The larvae, however, are to be met with in abundance in privet hedges. Even in the centres of large towns we may see them resting on the topmost twigs of a privet hedge, their beautiful green tint closely resembling that of the surrounding leaves. After a little experience they may be readily discerned by a careful observer, but there are certain signs by which their presence may be proved before they have been actually seen. Sometimes a number of the twigs are completely stripped of their leaves, even the midribs and the leaf stalks being almost or entirely devoured; and beneath the bushes are the large black masses of excrement that tell of the marauders above. When found, these larvae should always be removed on a piece of the twig to which they are attached, for they hold on so firmly by their claspers that it is sometimes almost impossible to remove them from their hold without injury.

These caterpillars may easily be distinguished from those of the other 'hawks' by the seven oblique stripes which adorn the sides. These are each composed of two colours, white and lilac, and form a pretty contrast with the bright green of the rest of the body. The horn is smooth and curved, and is black with the exception of part of the under side, which is yellow.

They are fully grown in August, and from the end of this month till the following June the chrysalides may be dug out from under privet and lilac bushes, both of which are attacked by the larva.

_The Spurge Hawk_ (_Deilephila Euphorbiae_)

This is a very rare British species; in fact, it has never been seen in this country in its perfect state, but the larva has been found plentifully at Appledore and Braunton Burrows, in North Devon, feeding on the sea spurge (_Euphorbia Paralias_).

The perfect insect is shown on Plate IX (fig. 2).

The caterpillar is black, with a large number of small yellowish white dots, and two rows of spots of the same colour on each side. There is also a red line on each side, and another down the middle of the back. The horn is rough and red with a black tip. It feeds during August and September.

_The Small Elephant Hawk_ (_Chaerocampa Porcellus_)

This pretty insect is one of the smallest of our hawk moths. It is widely distributed, being met with in many parts of England and in the south of Scotland. It flies in June.

The fore wings are of a dull yellow colour, with rosy-red hind margins, and a broad border of the same tint on the costal margin. The hind wings have also a rosy-red hind margin, and are smoky black along the costae, and yellow in the anal angle. The body is coloured with bright rose-red, tinged with olive on the foremost and hindmost segments.

The popular name of this and the following species has been applied because of the power which the caterpillar has of extending and retracting its front segments, a peculiarity which has given the idea of a semblance to the elephant's proboscis. The colour of the caterpillar is light-brown or green, mottled with dark-brown, dark-green, or black. It has a conspicuous eye-like spot on each side of the fifth and sixth segments, and has no horn.

This larva may be found in July and August, feeding on species of bedstraw (_Galium verum_, _G. Mollugo_, and _G. palustre_), willow herb (_Epilobium hirsutum_), or the purple loosestrife (_Lythrum Salicaria_).

_The Large Elephant_ (_Chaerocampa Elpenor_)

This species (Plate IX, fig. 3) is very similar to the last in form and markings; but is, as its name implies, larger.

The caterpillar, too, is very like that of the last species, but may be distinguished from it by the possession of a short black horn, tipped with white, on the 'tail.' Its colour is green or brown, mottled and spotted with black. The eye-like spots on its fifth and sixth segments are black, and each contains a brown spot surrounded by a white line.

Its chief food plants are the hairy willow herb (_Epilobium hirsutum_), three species of bedstraw (_Galium verum_, _G. Mollugo_ and _G. palustre_), the purple loosestrife (_Lythrum Salicaria_), and the enchanter's nightshade (_Circaea lutetiana_). It will also feed on the vine and the apple in confinement.

_The Eyed Hawk_ (_Smerinthus Ocellatus_)

Our next genus (_Smerinthus_) contains three well-known moths, all of which have the hind margin of the fore wings angulated or indented.

The first is the Eyed Hawk, represented in fig. 4 of Plate IX and named after the beautiful and conspicuous eye-like spot near the anal angle of each hind wing.

The caterpillar has a rough green skin, sprinkled with white dots, and marked with seven oblique white lines on each side, each of which is bordered with dark green above. The spiracles are pinkish, surrounded by violet rings; and the horn is blue.

The moth flies during May, June, and July; and the caterpillar may be found in plenty during August, feeding on the apple, willow (_Salix alba_), sallow (_S. cinerea_ and _S. Caprea_), poplar (_Populus alba_ and _P. nigra_), aspen (_P. tremula_), and the blackthorn (_Prunus spinosa_).

As with many other _Sphinges_, the larvae are much more commonly seen than the perfect insects; but the latter may often be met with resting on tree trunks and fences in the neighbourhood of their food plants.

_The Poplar Hawk_ (_Smerinthus Populi_)

This moth is very common and very widely distributed, and may be easily found in any of its stages. The perfect insect flies during May, June, and July; and being rather heavy on the wing, it is easily taken with a net as it hovers round the branches of its favourite trees or among the flowers of gardens at dusk. The larva may be beaten from the boughs of poplars and sallows during August and September, and during the latter month may often be seen creeping down and around the trunks of these trees, searching for a suitable spot in which to undergo its changes. The pupa may be dug out of the soil at the foot of the same trees during the autumn, winter, and spring months.

The fore wings are ashy grey or greyish brown, marbled with darker tints, with a conspicuous white spot near the centre. The hind wings are similarly coloured except at the base, where there is a large patch of brick-red.

The caterpillar is rough, of a pale green colour dotted with yellow, with seven oblique yellow stripes on each side. The spiracles are white, edged with red; and the horn is yellow on the upper, and reddish on the under side. Its chief food plants are the poplar, the Lombardy poplar (_Populus pyramidalis_), aspen (P_. tremula_), and sallow (_Salix Caprea_ and _S. cinerea_).

_The Lime Hawk_ (_Smerinthus Tiliae_)

This beautiful moth (fig. 5, Plate IX) is easily identified by its rich olive green and brown wings, the fore pair of which have very conspicuous patches of deep olive, sometimes uniting to form a continuous central bar. It flies in May and June.

The caterpillar is rough, of a pale green colour, dotted with yellow, with seven oblique yellow stripes on each side. Thus it is very like the larva of _Populi_, but may be distinguished from that species by the orange spiracles, and by the horn, which is rough, blue above, and yellow beneath. Behind the horn, too, there is a flat purple or violet scale with an edging of orange.

The food plants of this species are the lime (_Tilia vulgaris_), elm (_Ulmus campestris_), and the hazel (_Corylus Avellana_), from which the larvae may be beaten in August and September, and from under these the pupae may be dug out during the winter months.

_The Humming-Bird Hawk_ (_Macroglossa Stellatarum_)

The genus to which this insect belongs contains three interesting British species. Their antennae are thickened toward the end, but terminate in a small curved bristle. Their wings are rather short and broad; their bodies are very thick, terminating in a broad tuft of hair; and the perfect insects fly during the daytime, delighting in the hottest sunshine. The larvae feed principally on low-growing plants, and undergo their metamorphoses on the ground among the foliage.

On Plate IX (fig. 6) one of these pretty moths is shown. It is the Humming-bird Hawk, so called on account of its exceedingly rapid humming-bird-like flight, accompanied by a soft humming sound.

This insect is very common; and, being very partial to the attractions offered by many of our favourite garden flowers, it ought to be well known to all observers of nature.

Take your stand near a bed of petunias or verbenas, or close to a honeysuckle in bloom, on any hot summer's day, and you are almost sure to be rewarded by a peep at the wonderful flight and interesting ways of this moth. It makes its appearance so suddenly that you first view it as an apparently motionless insect, suspended in the air, and thrusting its long proboscis into the tube of an attractive flower. Its wings vibrate so rapidly that they are quite invisible, and give rise to the soft hum already mentioned. Then it darts from one flower to another, making a similar brief stay before each while it sucks the grateful sweets. Raise your hand as if to strike, and suddenly it vanishes you know not where. But it is as bold as it is wary, and will often return to the selfsame flower as if to defy your power. A sharp sweep of your net in a horizontal direction, or a sudden downward stroke, _may_ secure it; but if you miss it, as you probably will, it will disappear like a phantom, and give you no opportunity of making a second attempt.

This moth is on the wing throughout the hottest months of the year--May to September, and will often greet you as you roam over flowery banks in search of butterflies.

The caterpillar feeds on the lady's bedstraw (_Galium verum_), hedge bedstraw (_G. Mollugo_), and the goose grass (_G. Aparine_), and may be searched for in August and September. It is rough, green or brownish, and dotted with white. Along each side are two light lines. The horn is thin and short, rough, and points upwards.

_The Broad-bordered Bee Hawk_ (_Macroglossa Fuciformis_)

The two other moths of this genus are called Bee Hawks from their resemblance to the humble bee. They are very much alike, but may be distinguished by a difference in the width of the dark border of the wings; and are named Broad-bordered and Narrow-bordered respectively.

The former is illustrated in the woodcut appended. The fore wings are transparent like those of bees, with a dark central spot and a broad reddish-brown hind margin. The base and costa are black and tinged with green. The hind wings are similarly coloured, but have no central spot. The body is olive-brown, with a broad reddish belt, and behind are tufts of hair, which are spread out when the insect flies, just after the manner of the tail feathers of a bird. The moth flies in May.

The larva resembles that of _Stellatarum_, but exhibits a violet tint above the legs. Its horn, too, is curved, and of a reddish or brownish colour. It feeds on the honeysuckle (_Lonicera Periclymenum_), ragged robin (_Lychnis Flos-cuculi_), evening campion (_L. vespertina_), red campion (_L. diurna_), lady's bedstraw (_Galium verum_), and the field scabious (_Scabiosa arvensis_), during the month of July.

Family SESIIDAE--THE CLEARWINGS

This family contains fourteen very pretty British insects that differ very much from other moths in many important and interesting particulars.

Their antennae, like those of the _Sphingidae_, are thickest beyond the middle, and those of the males are slightly _ciliated_ or hairy. Their bodies are slender, and terminate behind in tufts of hair. The hind wings in all cases are transparent, margined and veined with black or brown; and the fore wings also, in most cases, have transparent bases.

These moths delight in the hottest sunshine, and may be seen gracefully hovering over the flowers in our gardens, looking more like gnats, bees, and wasps, than moths.

The larvae of these insects are all wood-eaters, and spend their time within the stems of shrubs and trees, eating out galleries in the material that forms both their food and their home. Within these they also undergo their changes, and do not expose themselves to the free air and light till they reach their perfect stage.

_The Hornet Clearwing of the Poplar_ (_Trochilium Apiformis_)

We can find space for a mention of only two of the clearwings, the first of which is an insect that closely resembles the dreaded hornet, and whose larva feeds in the stems of poplars--features which will account for the above name.

The head of this species is yellow, its thorax brown with a large yellow patch on each side, its abdomen yellow with two brown belts, and its legs reddish orange. The front wings are transparent, with brown costae, and all the wings are margined with brown.

The caterpillar, when full fed, makes a cocoon with silk and the chips of wood that it has bitten off; and in this undergoes its metamorphoses. It is fully grown in April, and the moth flies from the end of May to the end of July.

There is another 'Hornet Clearwing,' the larva of which feeds on the stems of osiers. It may be distinguished from the species just described by a yellow 'collar' between the head and thorax, both of which are blackish.

_The Currant Clearwing_ (_Sesia Tipuliformis_)

This is by far the commonest of all the Clearwings, and only too well known to those who grow currants. Examine the shoots of _Ribes rubrum_ (red currant) and _R. nigrum_ (black currant), especially those that present a withered or half-withered appearance, and you will almost certainly meet with signs of the presence of this intruder. Little wriggling larvae occupy the pithless stems throughout the winter and spring. These are full grown in April, and in June the pretty little moth emerges through a hole in the side of a shoot, leaving the empty pupa case within its former home.

The fore wings of this moth have black margins, and a black transverse bar beyond the middle. The body is black, with three pale yellow belts, and black tufts of hair at the tip.

Family--ZYGAENIDAE

The remaining family of the _Sphinges_--the _Zygaenidae_--includes seven British species, three of which are known popularly as the Foresters and the others as the Burnets.

Their antennae are thickest beyond the middle, but do not terminate in a hook. Their wings are narrow and completely covered with scales.

These moths are very sluggish creatures, spending the greater part of their time at rest on the stems of low-growing plants. When they do fly, their flight is short and heavy, and their pretty wings glisten in the sunshine (for they are lovers of the sun), giving them the appearance of bees rather than of moths. On account of this natural sluggishness, they are exceedingly local, for they never move far from the spots where their food plants abound, and where they had previously spent the earlier stages of their existence. Thus we often come across a very limited piece of ground actually alive with them, and outside which not a single specimen is to be seen.

The larvae, too, are sluggish creatures, with soft and plump cylindrical bodies and no horns. I will briefly describe three members of this family.

_The Forester_ (_Ino Statices_)

The fore wings of this species are semi-transparent, and of a beautiful glossy green. The hind wings also are semi-transparent, but of a dull smoky tint. The thorax and abdomen are both of a brilliant metallic green colour. The tips of the antennae are blunt, and the male may be distinguished from his mate by these organs being slightly fringed or ciliated.

The caterpillar is dingy grey or greenish, with a row of black spots down the back, and a whitish stripe on each side. It feeds on the common sorrel (_Rumex acetosa_) and the sheep sorrel (_R. acetosella_), and when fully grown it spins a cocoon on the stem of its food plant, and there changes to a chrysalis.

The larva may be found during May and early June. The chrysalis state lasts only a few days, and the moth is on the wing during June and July.

_The Broad-bordered Five-spotted Burnet_ (_Zygaena Trifolii_)

On Plate IX (fig. 7) will be found a coloured representation of this Burnet. The two crimson spots in the base of the fore wing are very close together, and often touch. The same remark also applies to the two spots on the middle of the wing. A glance at the list of British Moths (Appendix I) will show that we have also a _Narrow_-bordered Five-spotted Burnet. This insect is very similar to the species now under consideration, but may be identified by the narrower purplish margin on the hind wings, and also by the shape of the antennae, which are not thickened so much near the end as they are in _Trifolii_.

The larva of the present species is yellowish or greenish, with a row of black spots on the back and a row on each side. It feeds on the bird's-foot trefoil (_Lotus corniculatus_), hop trefoil (_Trifolium procumbens_), and the horse-shoe vetch (_Hippocrepis comosa_) in May. Late in May or in early June the chrysalis may be found in a silken cocoon attached to a stem or leaf; and the perfect insect flies during June and July.

_The Six-spotted Burnet_ (_Zygaena Filipendulae_)

So common is this moth, and so conspicuous when it flies in the blazing sun, that it must be familiar to almost everybody. On a bright midsummer day hundreds may often be started from their grassy beds from one little patch of ground.

The colouring of the wings is much the same as in the last species, but there are two crimson spots instead of one near the tips of the fore pair.

The larvae may be seen in vast numbers during May and June, feeding on clovers (_Trifolium pratense_ and _T. repens_), and the bird's-foot trefoil (_Lotus corniculatus_); and in the latter month thousands of the chrysalides, inclosed in shuttle-shaped cocoons on grass stems, may be seen on downs and sunny banks in almost every part of the country.

The caterpillar, which is yellow, may be known by the two rows of black spots that adorn each segment of the body.