Purple Hairstreak

Purple Hairstreak Neozephyrus quercus (Linnaeus 1758)

Family: Lycaenidae, sub-group Theclinae (‘the Hairstreaks’)

All photos by Martin Partridge

The largest of the three hairstreaks found in Yorkshire, this is the only one which will habitually bask with wings open. The upperwing is dark, and has an overall purple sheen in the male, and purple patches on the forewings in the female. The underside is silvery-grey, with a jagged white line running from top to bottom, and a distinct black-pupiled orange eye-spot near the hind edge, with a further orange marking below this. Next to the eye-spot, on the edge of the wing there is a short tail.

Habitat

Typically a woodland butterfly, found on or near oaks (its larval food plant), it may also be seen in parkland, large gardens, or hedgerows. It favours trees with a south-facing aspect, along rides, woodland edges and clearings where it is sheltered and sunny. It can be found on either of our native oaks, as well as on introduced species.


An elusive butterfly, it spends much of its time in the treetops where it is best observed through binoculars although it will occasionally descend to ground level. It is often active on warm, sunny evenings, when large numbers may be seen at favoured sites, although it has been noted that if the sun disappears behind clouds all activity suddenly ceases.


Like the White-letter Hairstreak this species feeds on honeydew secreted by aphids, which collects on the surface of leaves, only rarely nectaring on flowers.


There is a single record of an individual seen on moorland in VC62 well away from any areas of woodland, suggesting that this species may be capable of dispersing a considerable distance.

Distribution

Most common in the western part of the county (VCs 63, 64, & 65), with fewer records from VCs 61 & 62. It is likely more common than records suggest as its elusiveness may mean that many colonies are overlooked.


At a handful of sites it may be seen in large numbers, with Notton Wood, nr Wakefield and Hollins Wood, nr Barnsley (both VC63), and Cardale, Harrogate (VC64) producing extremely high counts over the years.

Life Cycle

Single brooded, with adults typically on the wing in July and August, although in good years emergence may begin in mid to late June and continue until early September. There is a single record of an adult in early October!


The eggs are laid on the twigs of oak, often at the base of a bud or cluster of buds. They may be laid at any height, but usually on branches that are in full sun. They are quite conspicuous, so may be searched for throughout winter, providing evidence for breeding colonies even if the adults haven’t been recorded. The larvae develop within the eggs in about three weeks, and remain within the eggshell over winter, not hatching out until the following spring. The larvae burrow into the buds to feed, until the first moult, after which it lives outside the bud, concealed by a loose silken web. When fully-grown, the larvae resemble a fleshy brown woodlouse and are well camouflaged on the leaf buds.


Pupation takes place just beneath the surface of the soil, in moss, or in leaf litter. Pupae have been found in the nests of ants. Both larvae and pupae produce secretions which attract ants, and it seems that during the pupal stage this butterfly is more dependant upon ants than was previously realised, which may help to explain its absence at sites which otherwise seem to provide suitable habitat.

Status

The species is not under threat.

Aberrations


Dave O'Brien 15/03/21