About sixty species belonging to this family, scientifically known as the
Sphingidæ, are recorded from the Palæarctic region, and of these
twenty-seven are found in Europe. About ten only can be considered as true
natives of the British Isles; seven others, though found here, are
distinctly aliens, and their visits, at least as regards some of them, to
our islands, exceedingly irregular.
Most of the moths are of large size, many of the caterpillars are of noble
proportions, and in both stages they are not difficult to find, if looked
for in suitable places and in their proper season. The caterpillars of
several kinds, owing to the exposed way in which they feed or rest, are
especially noticeable on bush and hedgerow; the chrysalids, although
subterranean, are often freely obtained by turning up the soil around
trunks of trees, or under plants, upon which the caterpillars feed.
THE LIME HAWK-MOTH (_Dilina_ (_Mimas_) _tiliæ_).
The four specimens shown on Plate 3 represent the more or less ordinary
form of this moth. The pale pinkish grey, or reddish brown, fore wings are
sometimes tinged with greenish in the paler forms; the irregular shaped
band crossing the {18} central area of the wings is olive green, usually
dark, and generally edged with whitish. This band is sometimes entire
(typical), but more frequently it is broken about the middle. The outer
third of these wings is more or less greenish or mottled with green, and a
mark near the tip is whitish.
Variation is chiefly connected with the modifications that occur in the
upper or lower, sometimes both, portions of the central band; the lower
seems to be the first to disappear, then the upper passes through various
stages of reduction until it becomes simply a spot or dot about the centre
of the wing. Specimens are occasionally found or reared, in which every
trace of the band has departed from one or both fore wings. The greenish
outer border of the wings is inwardly margined with darker, well defined
and band-like in some examples, but less clearly marked, or even absent, in
others. Near the base of the fore wings are often two dusky greenish cross
lines. The hind wings, generally pretty much of the same ground colour as
the fore wings, have a dusky band-like shade of variable width on the outer
third; sometimes these wings are entirely dusky, approaching blackish. Very
rarely specimens are bred in which there is no trace of green colour. Such
an example was reared by Mr. Frohawk in April, 1882, from a caterpillar he
found in Surrey. In this aberration all the markings (normally green) are
light burnt-sienna red, the usual whitish blotch at the tip of the fore
wings is pink; ground colour also pink, slightly tinged with grey in
places. So variable is this moth in colour and markings, that in some
collections at least one cabinet drawer is given to it so that the range of
aberration may be adequately shown. Already about eighteen colour
modifications have been named, and at least eight band variations have also
received names.
The egg is similar in general appearance to that of the next species (see
Plate 4). Dr. Chapman states that it is more densely covered with an
indiarubber-like gum, and this may cause it to seem darker than the eggs of
the Eyed and the Poplar Hawk-moths. The eggs are laid singly or in pairs on
the underside of elm or lime leaves.
[Illustration]
Pl. 2.
LIME HAWK-MOTH.
_Caterpillar and chrysalis._
[Illustration]
Pl. 3.
LIME HAWK-MOTH.
{19} The figure of a nearly full-grown caterpillar (Plate 2) is from a
drawing in colour by Mr. A. Sich. Shortly, the caterpillar may be described
as green, roughened with yellow points, and with seven yellow oblique
stripes on the sides, each edged above with purplish and reddish; the
spiracles are ringed with reddish, and the curved horn is blue, inclining
to yellowish beneath and at the tip; the roughened shield on the last ring
of the body is reddish, marked with yellow. Head triangular, smoother than
the body. Quite in its infancy, the caterpillar is a long, thin creature;
the horn, which is divided at the tip, is covered with short, stiff hairs,
and appears blackish; later on the horn becomes reddish, and the side
stripes appear on the body. Although alder, birch, and several other shrubs
and trees have been mentioned, there is no doubt that the foliage of elm
and lime is the chief food of the caterpillar in a state of nature. Found
in July and August.
The chrysalis is dark reddish, and somewhat rough. As a rule, it is
enclosed in a very fragile cell which the caterpillar makes for itself
after burrowing a few inches underground and near the trunk of an elm or a
lime tree. There are, however, records of the chrysalis having been found
in crevices of bark high up on elm trees.
In May and June the moth emerges, usually in the afternoon, and may
sometimes be found on the trunks of trees, or on palings near limes and
elms. When at rest the fore wings are so arranged over the hind ones that
they, in conjunction with the upturned body, give the insect more the
appearance of a bunch of immature leaves than of a moth.
The species is widely distributed throughout the southern counties of
England, and in some of them, more especially around London, it is common.
In the Midlands it seems to be {20} scarce, and apparently does not occur
further north than Yorkshire, from which county there is only a single
record. It is common in Europe, except in the more northern and southern
parts, and its range extends eastwards into Siberia.
THE POPLAR HAWK-MOTH (_Smerinthus_ (_Amorpha_) _populi_).
On Plate 5 are three slightly different examples of this moth. In colour it
is most frequently ashy grey, with a brownish central band, and other
markings; there is a white spot on the fore wings and a conspicuous red
patch at the base of the hind wings. The female is generally paler than the
male, and often has a pinkish tinge. Specimens of a pale buff colour are
sometimes obtained, and these are most often of the female sex, although
male examples of this form are not unknown. Among unusual aberrations is
one described as having the wings, legs, thorax, and abdomen of a colour
between brick-red and chocolate, suffused with a whitish bloom as on ripe
plums. Another had the hind wings unadorned with red. Specimens from
Aberdeenshire and Sutherlandshire are smaller than English examples, and
the males are almost always more brightly and distinctly marked.
A very large number of Gynandrous, or "hermaphrodite" specimens have been
recorded, several of them from Britain; in most of these the
gynandromorphism is bilateral, that is the insect is wholly male on one
side, and entirely female on the other. In some the right side is male, in
others the left side; the opposite side in each case being female. Much
information on this subject and on Hybridism of the Sphingidæ will be found
in Tutt's "British Lepidoptera," vol. iii.
The pale shining green eggs are laid, generally singly, but sometimes in
twos, threes, or more, on either surface of a leaf of poplar or sallow. Now
and then batches of eggs may be found, and these have probably been laid by
females that were crippled on emergence, or had been afterwards injured in
some way and so were unable to fly.
[Illustration]
Pl. 4.
POPLAR HAWK-MOTH.
_Eggs, natural size and enlarged; caterpillar and chrysalis._
[Illustration]
Pl. 5.
POPLAR HAWK-MOTH.
{21}
[Illustration: FIG. 17.