Mention to anyone with a keen interest in UK butterflies the wonderful name Glapthorn Cow Pastures and one species springs to mind, the Black Hairstreak (Satyrium pruni). Glapthorn, as the name suggests, used to be grazing land, now it is a wonderful woodland nature reserve. It is located about 3 miles north of the historic town of Oundle in Northamptonshire, a drive of 2 1/2 hours from home.
The Black Hairstreak is a small and rare butterfly. In the UK it can only be found in a narrow band of woodland stretching from Peterborough to Oxford, it also has one of the shortest flight periods, only 2 to 3 weeks in mid-June. When I visited last year I struggled to see two in an afternoon, this year has been a record emergence and there was over twenty around their favourite dewberry bushes when the sun shone. Unlike most butterflies the Hairstreaks are very approachable allowing for some great photo opportunities.
The Black Hairstreak spends most of the day in the tops of trees or scrub feeding on aphid honeydew. They need banks of blackthorn in sunny spots to lay their eggs on, the egg overwinters and the caterpillar hatches in spring. The adults have a wingspan of 35-40mm (about 1 1/2 inches).