Currently to be seen flying over most grassy areas in the UK, especially sunny and sheltered spots including roadside verges is Britain’s only “Copper” butterfly, the Small Copper Lycaena phlaeas.
This energetic little butterfly belongs to one of the eight or so subfamilies of the Lycaenidae, the largest butterfly family (6000+ species) after the Nymphalidae. There are three subfamilies to be found in Europe, the Polyommatinae (Blues), Theclinae (Hairstreaks) and the Lycaeninae (Coppers). There is a fair amount of ecological separation between these three groups, with Hairstreaks using trees and bushes as larval foodplants, Blues mostly using members of the pea family and feeding on or in seed heads, and the Coppers using various species of sorrel or other broad leaved herbs and feeding on the underside of the leaves. Almost all lycaenids have at least some association with ants, which some species such as the Large Blue are completely dependent on.
Small Coppers have several broods during the year, beginning with a spring brood in May or June. The male establishes a small territory around a flower head or a prominent stone from which he flies to court passing females. At night the adults roost on grass stems.
Once mated, the female seeks out Common Sorrel Rumex acetosa or Sheep’s Sorrel to lay her eggs, usually singly on the upper surface of the joint between leaf blade and stalk. The eggs take one or two weeks to hatch depending on the weather, and the small, slug-like caterpillars feed on the underside of the leaves, leaving “windows” in the upper leaf cuticle. The pupa is dumpy and may be formed in ant’s nests in the wild, or possibly in the depths of grass tussocks.
There may be several broods each year, especially in the south in warm years, but eventually the changing seasons cause the later larvae to go into hibernation at the base of the plants until the return of spring starts the cycle over again.
Although there are many species of copper across Europe and Asia, in Britain there is currently only one. Until 100 years ago there were two, the other being an endemic subspecies of the Large Copper Lycaena dispar. This became extinct as a result of changes in land use in the East Anglian fens, its last redoubt, and also over-collection by Victorian and Edwardian lepidopterists. Attempts were made for many years to re-establish the species using as a source population the Dutch subspecies (itself now Critically Endangered) but these proved unsuccessful and any attempts have been abandoned for now. There is one other subspecies, L.dispar rutilus, which is widespread in wetlands across Europe but is declining in many areas as a result of land use changes.
(Large Copper image from Wikipedia, Small Copper my own)