Volume I Part 3 (1/2)

CONVOLVULUS HAWK-MOTH, _Herse_ (_Sphinx_) _convolvuli_.

The older writers on British moths called this the ”Unicorn” or ”Bindweed Hawk.” The fore wings are whitish grey, mottled with darker tints, and, in the male, clouded with blackish about the middle of the wing; the central third is limited inwardly by a double blackish, wavy line, and outwardly by an irregular, toothed, whitish line; running from one to the other are two black streaks between the veins, and a similar streak nearer the costa is waved upwards to the tip of the wing. The hind wings are whitish grey, with a black stripe near the base, and two blackish bands between the stripe and the outer margin. The thorax agrees in colour with the fore wings; the tapered body has a broad grey stripe, enclosing a central black line along the back, broad red and black and narrow white bands on each side (Plate 10).

The egg has been described as bright green in colour, and smaller than that of the Privet Hawk. A female moth captured at Brighton on July 18, 1898, deposited twenty-five eggs on _Convolvulus arvensis_ up to July 20, and the next day a further eight were counted. The moth died on the 22nd.

Caterpillars hatched out July 27-28. These were whitish green, with a rough blackish horn; after second moult they became green, with a darker green stripe along the back, but without oblique side stripes.

[Ill.u.s.tration]

Pl. 10.

CONVOLVULUS HAWK-MOTH.

[Ill.u.s.tration]

Pl. 11.

1. CHRYSALIS OF DEATH'S-HEAD HAWK-MOTH.

2. ” ” CONVOLVULUS ” ”

3, 3a. CATERPILLAR AND CHRYSALIS OF PINE HAWK.

{29} In its more usual form the caterpillar, when full grown, is bright apple-green, narrowly streaked with black; oblique stripes on the sides yellowish; horn reddish, tip black. Head green, with black stripes. In some examples the side stripes are edged above with bluish black; in others there are blackish, more or less square, spots on the back, and patches on the sides. Sometimes the general colour is blackish brown, with ochreous bands and streaks. (This form is figured on Plate 9). When it occurs in these islands it is generally found on the small bindweed (_Convolvulus arvensis_), but it will eat _C. sepium_ and _C. soldanella_, and also the cultivated kinds.

Referring to the caterpillar in Britain, Moses Harris, in 1775, wrote, ”I never heard of but two that were ever found--one by Mr. South [or Smith] of Hamps.h.i.+re, which, he said, was green, and appeared in other respects so like the privet that he was deceived. He fed it on the leaves of the lesser bindweed. It changed into the chrysalis in the earth, in July, and the moth was produced in September” (Dale).

The caterpillar figured by Harris is of the brown form, so we see that even at this early date something was known of the life history of this moth and the variation of the caterpillar. Since that date and up to 1894 only very few larvae appear to have been found in our islands. Barrett states that it is doubtful if more than twenty had then been recorded. In 1895 caterpillars were obtained in Cornwall (four) and in Kent (two). Then for five years little or nothing was reported about this stage, although the moth seems to have occurred in varying numbers each year. In 1901, August and September, over one hundred were reported, rather more than half of which were taken from a hedgerow, overgrown with _C. sepium_, in {30} Northumberland; twenty-six were obtained on the bindweed growing on Lancas.h.i.+re sandhills, thirteen or fourteen in Ess.e.x, and others in Bedfords.h.i.+re, Kent, Hants, Dorset, and Devon.

Mr. Bell-Marley obtained thirty eggs, September, 1897, and although these were kept in a cold room, thirteen caterpillars hatched, September 21. They were supplied with _Convolvulus arvensis_ and _C. soldanella_, and seemed to relish one as much as the other. Seven died during the first three moults. The bindweeds being nearly over, seedlings were raised by forcing, but before these were ready the larvae had been on short commons, and just immediately before the seedlings came to hand, had been twenty-four hours without food. On these tender seedlings and some endive the remaining larvae, six in number, attained full growth in December. Two subsequently died in the first half of that month, and the others went under the soil.

Only one, however, managed to a.s.sume the chrysalis state.

A small caterpillar, about one week old, described by Paymaster-in-Chief G.

F. Mathew (”Notes on Lepidoptera from the Mediterranean,” _Entom._, x.x.xi.

115), was 1 inch long, pale glaucous green in colour, and thickly covered with raised white dots; oblique side stripes white, bordered above with dark green. On September 26, 1897, this caterpillar, which had been found on September 18, was nearly full grown, and the writer goes on to state that when gathering bindweed he obtained either eggs or tiny caterpillars at the same time, and he eventually found that he had eight of them altogether. They fed up rapidly, as a caterpillar, hatched about September 27, had gone down on October 18. Owing to accident, four produced deformed chrysalids, but each chrysalis resulting from the others was perfect and healthy on February 15, 1898. The large reddish-brown chrysalis is figured on Plate 11, and it will be noted that the ”tongue” case forms a curious bent projection not unlike the handle of a pitcher. To give some idea of the irregular way in which this migratory species visits our islands, it will suffice to note the records only since 1894. Previous to that year it was common, more or less generally, in 1846, 1868, 1875, 1885, and 1887.

[Ill.u.s.tration]

Pl. 12.

1. PRIVET HAWK-MOTH.

2. PINE HAWK-MOTH.

[Ill.u.s.tration]

Pl. 13.

PRIVET HAWK-MOTH.

_Eggs, natural size and enlarged; caterpillars and chrysalis._

{31} In 1895 an invasion seems to have effected a landing in the autumn, on the south-west coast, chiefly, perhaps, in the Portland district, where some fifty individuals were captured between August 12 and October 7; twenty-three were caught near Bournemouth in August and September; sixteen were taken at Christchurch, August 11 to October 2; and eight were recorded from Milford. Several were reported from Devon, but only two from Cornwall, although four larvae were found in October at Port Wrinkle in the latter county. At Cork, in Ireland, ten specimens were obtained in October.

Eastward, the captures in September were Norfolk (seven), Ess.e.x (one), Lincoln (one). Odd specimens were taken here and there in Kent, Surrey, and Herts. Several were reported from Gloucesters.h.i.+re, and one from South Wales. The northward extension was evidenced by the capture of one example at Alnwick, in Northumberland, in September, and of two in Aberdeens.h.i.+re, one as early as August 31, the other September 9.

The moth was almost a defaulter in 1896, but in 1897 about forty specimens were taken, twenty-seven of which occurred in the Scilly Isles and eleven at Portland (August 14 to September 16). One example was reported from Yorks.h.i.+re and another from Sutherlands.h.i.+re, both in September.