The caterpillar feeds, August and September, on spurge (Euphorbia paralias, and E. cyparissias). When full grown the head is crimson red, marked on the crown with black; the body is black, but so thickly sprinkled with yellow dots that much of the black colour is obscured; the larger spots are often crimson, but sometimes they are yellow, or even cream coloured; the stripes along the back and below the yellow spiracles are crimson, as also are the legs and feet; the spiny horn is crimson with a black tip. In a younger stage the head and the horn are orange, the latter black tipped; the body is yellow with patches of black around the paler yellow spots on the back. Chrysalis pale brownish, minutely dotted with black; the head and thorax are marked with blackish, and the rings of the body have narrow, interrupted, blackish bands; the wing and antennæ cases are covered with fine short blackish streaks; tail spike blackish, somewhat flattened, and the acute point black (Plate [1], Fig. 1; [14], Figs. 2, 2a).
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| Pl. 14. | ||
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| Caterpillars and chrysalids. |
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| Pl. 15. | ||
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The moth usually emerges in June or July of the year following pupation, but it may come out the same year; on the other hand, it has been known to remain in the chrysalis for two winters. Dr. Chapman has noted the emergence of the moth eighteen days after the pupa was formed.
Little, if anything, appears to have been known of this species as an inhabitant of Britain until 1806, when Mr. Raddon, who was staying at Instow, in N. Devon, had a caterpillar brought to him by a fisherman. From that time, and up to 1814, a large number of the caterpillars were obtained from Euphorbia paralias growing on Braunton Burrows, a long stretch of sandhills on the north Devonshire coast, accessible from Barnstaple or Ilfracombe, which, when I visited the locality some twenty-five years ago, was greatly favoured by rabbits. One would suppose that the Spurge Hawk caterpillars must have been pretty abundant at the time Raddon made his observations, as he states in a note on the subject published in the Entomological Magazine for 1835, that on leaving the ground one evening at dusk he hastily cut an armful of spurge, which he took home and put in water. Next morning he "found the food covered with not less than a hundred minute larvæ about a day or two old." This must have happened prior to 1814, because the species seems to have entirely disappeared about that year. The Rev. E. N. Bloomfield, in his catalogue of the Lepidoptera of Suffolk, mentions a moth bred from a larva found near Landguard Fort about 1865. He adds that the food plant was then abundant there. At a meeting of the Entomological Society of London held in October, 1876, a letter was read from Mr. Higgins concerning the reported finding of the caterpillars of this species in a locality near Harwich in 1873. It was stated that the spurge (Euphorbia paralias), had not only been
seen in the particular spot, but in other parts of the same district also.
In the Entomologist for 1893 there is a very circumstantial account of the finding of eighteen or nineteen Spurge Hawk caterpillars on the Cornish coast in the autumn of 1889. From these, eight moths resulted in May-July, 1890, and one in June, 1891.