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 t.i.tle 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 superst.i.tious 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 superst.i.tious 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.
[Ill.u.s.tration: FIG. 97.--THE DEATH"S-HEAD HAWK MOTH.]
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.
[Ill.u.s.tration: FIG. 98.--THE LARVA OF ATROPOS.]
_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 ma.s.ses 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).
[Ill.u.s.tration: FIG. 99.--THE CATERPILLAR OF EUPHORBIae.]
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 a.n.a.l 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.
[Ill.u.s.tration: FIG. 100.--THE SMALL ELEPHANT HAWK MOTH.]
This larva may be found in July and August, feeding on species of bedstraw (_Galium verum_, _G. Mollugo_, and _G. pal.u.s.tre_), 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.
pal.u.s.tre_), 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 a.n.a.l 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_)
[Ill.u.s.tration: FIG. 101.--THE POPLAR HAWK.]
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_).