Brown Hairstreak. © 2021 Gillian Thompson.
The Brown Hairstreak is a single brooded species being on the wing from late July to early September, with the males emerging first. The elusive adults occur in low numbers over large areas. Males may congregate around a 'master tree', usually an Ash tree near the breeding colony.
The butterflies feed primarily on aphid honeydew which coats the leaves of Ash trees although adults can sometimes be seen feeding on flowers. The females may be found feeding on Fleabane (Pulicaria dysenterica), Hemp Agrimony (Eupatorium cannabinum) and Brambles (Rubus fructicosus) between periods of egg laying.
The adult male Brown Hairstreak lacks the golden orange flashes on the upper-forewings shown in the photo right.
Areas of extensive hedgerows or woodland edges where Blackthorn is present is required. Mechanical flailing of hedgerows during the autumn months has had a devastating impact on this species with the number of eggs which hatch the following spring being greatly reduced and causing local and regional extinctions as a result. This species could be much more widespread in our region if it was not for the extensive and often misguided use of the hedge flail by landowners and farmers.
It is possible that the Brown Hairstreak may occur in very small numbers in the south Warwickshire area. Recent egg searches on the border with Worcestershire have resulted in some eggs being found in our region although adult butterflies are yet to be recorded.
In 2010 a single adult was observed at King's Coughton, confirming the presence of the species on the Warwickshire / Worcestershire border.
The larvae of the Brown Hairstreak feed on Blackthorn (Prunus spinosa).
See maps below. Distribution text required.