Small Tortoiseshell (Aglais urticae)
This common butterfly is known as a garden species but is widespread over all types of habitat, from south to north. Small Tortoiseshells are commoner in this country than in many other parts of Europe, though they are not scarce anywhere.
Stinging nettle is the natural foodplant, although hops have been taken by captive larvae.
There are two or three broods in the year. Hibernation is in the adult stage, usually in buildings, holes in the ground, rotten trees, etc. Hibernated butterflies lay eggs in May, producing successive broods until September and occasionally October. Small migrations from abroad augment our native butterflies.
The eggs are laid usually in one single mass, on the undersurface of a leaf near the top shoot of the nettle plant. The female selects an open situation with care, often choosing a depression in the ground contour or a place where the nettles are shorter. To encourage this species it is necessary to cut or graze nettles before they become old, long and tough. Often the butterflies will select the same nettle patch year after year if the plants are kept in suitable condition. The newly hatched caterpillars congregate and cover themselves with a fine web of silk, under which they feed on the leaves, moving on to another tent when necessary, often joining it to the last with a trail of silk. As they grow they still cluster but are not covered. In the final instar the larvae split up and live in small groups or singly.
The chrysalis hangs from the tail, away from the foodplant, hidden in some natural place or under an eave or windowsill, in a shed or attached to a fence. The usual colour is dark mottled brown but varying degrees of gold are found and the best shining gold forms come from larvae which suspend themselves from the foodplant in the breeding cage. They can be encouraged to do this and will often cluster there, nearly all producing this exotically colourful pupa, while those which hang from the roof of the cage are brown.
The butterflies seen in the spring are those which have survived hibernation. The late summer butterflies often crowd the garden and feed on almost every flower available. Ice plant (Sedum spectabile) is a favourite and Michaelmas daisy and buddleia are also particularly attractive.