The Small Tortoiseshell (Vanessa Urticæ)
This butterfly is one of the most ubiquitous as well as prettiest that we have in this country. Its reddish-orange colour, marked with yellow patches, black spots, and blue crescents, gives it a charming appearance as it sits on a flower, or even on the ground, with wings fully expanded to the sunlight. When the wings are closed up, however, the butterfly seems to disappear, as the under side of the wings is quite sombre in colour. The only bright spot on the under side is the yellowish central area of the fore wing, and when the wings are held erect over the insect’s back this is not seen, but only the tips of these wings, which are of the same dull colour as the hind wings.
The ground colour is subject to modification as regards the shade of red in the orange, and this may be intense or reduced to just a mere tinge. Specimens have been taken on the wing in which the colour was some shade of buff, and the same kind of colour change will sometimes result from an over-long exposure to the action of ammonia. The black markings vary in size, and sometimes those on the costal area are more or less connected or even confluent (Fig. 22); a greater or lesser amount of blackish suffusion on the hind wings (Fig. 23) generally accompanies confluence of the costal spots on fore wings. The two black spots between veins 2 and 4 occasionally enlarge and unite, or, on the other hand, they decrease in size to vanishing point. Some specimens have black scales between the second costal spot and the black spot on the inner margin, and the space between these two spots may be entirely covered with black and so form a central transverse band (var. polaris). A modification of this form is shown on Plate 38, lower figure. The yellow patch between the second and third costal black spots is sometimes continued right across the wings to the yellow spot on the inner margin, and in this respect resembles an Indian form of the species named ladakensis. Dwarf specimens result, in most cases, when the caterpillars have fed on hop (Humulus); at least, this is so in confinement.
The egg is at first green, but after a time becomes tinted with yellow and the ribs stand out clear and transparent. The eggs are laid in a cluster on the under side of a terminal leaf of a nettle plant in May and again in July.
The adult caterpillar is yellowish, closely covered with black speckling and short hairs; there is a black line down the centre of the back, and this is bordered on each side by the clear ground colour. The spiracles are black ringed with yellow, and there is a yellowish line above them. The yellowish spines have black tips. Head black, hairy, and speckled with yellow. Individuals of another company were almost entirely black, the spines alone being tinged with yellow. These caterpillars are gregarious from the time they hatch from the egg until about the last stage.
The chrysalis is most often of some shade of grey and sometimes tinged with pinkish. The points on the upper parts of the body are in some examples metallic at the base, and occasionally the metallic lustre spreads over the thorax and other parts as well.
There are two broods in the year, one in June, the other in August and September. The latter brood, or at least some of the butterflies, hibernate and reappear in the earliest sunny days of spring. They have been seen on the wing as early as January and February (1896), and as late as December.
The geographical range of this species extends through Europe and Asia to Japan.