The caterpillar of the _Acherontia atropos_ (Fig. 194) is the largest of all European caterpillars. It attains to as much as four and a half inches in length by eight lines in diameter. Its colour is lemon yellow, which changes into green on the sides and belly. From the fourth to the tenth ring inclusively it is ornamented laterally with seven oblique bands of an azure blue, which are tinted with violet, and bordered with white on the side. These bands joining together over the back of each segment resemble so many _chevrons_ placed parallel to each other. The body is, moreover, dotted with black. At its extremity is a yellow horn, curved back like a hook, and covered with tubercles. The head is green, and marked laterally with a black stripe. It lives chiefly on the potato, and the _Lycium barbarum_, sometimes called the tea-tree, a shrub belonging to the _Solanaceæ_. It buries itself in the earth to change into a chrysalis (Fig. 195) of a bright chestnut brown. [Illustration: Fig. 195.--Chrysalis of the Death's-head Hawk-Moth.] [Illustration: Fig. 196.--Lime Hawk-Moth (_Smerinthus tiliæ_).] [Illustration: Fig. 197.--Larva of the Lime Hawk-Moth (_Smerinthus tiliæ_).] [Illustration: Fig. 198.--Eyed Hawk-Moth (_Smerinthus ocellatus_).] We will mention still further, in the family of the _Sphingidæ_, three species of the genus _Smerinthus_, which fly heavily and by twilight. The Lime-tree Hawk-moth (_Smerinthus tiliæ_, Fig. 196) has its upper wings grey with some shades of green, and moreover, in the middle of the wing an irregular band of a brownish green colour. The thorax, covered with hairs, is grey, with three green longitudinal bands. The abdomen is also grey. The moth flies heavily after sunset, and is found on the trunks of trees during the months of May and June. The larva (Fig. 197) is glaucous green dotted with yellow, and marked on each side with seven oblique lines of the same colours. Its wrinkly horn is blue above and yellow below. It is found on the lime and the elm. It buries itself at the foot of the tree on which it has fed to change into a chrysalis without making a cocoon. [Illustration: Fig. 199.--Poplar Hawk-Moth (_Smerinthus populi_).] We will content ourselves by here giving drawings of two other species of the same genus: the Eyed Hawk-Moth (_Smerinthus ocellatus_, Fig. 198), which is not rare during the months of May and sometimes August, the caterpillar of which lives on the leaves of willows, poplars, and fruit-trees; and the Poplar Hawk-Moth (_Smerinthus populi_, Fig. 199), whose caterpillar (Fig. 200) lives on the poplar, the aspen, and sometimes on the willow and birch.