I had the distinct honour of adding a butterfly to the campus species list this week, in the shape of a rather smart White Letter Hairstreak. New moths come along on a near weekly basis – hardly surprising since we’ve recorded barely 1/10th of the UK fauna – but butterflies are far less diverse and consequently new site records are much more difficult to come by. It was in the small clearing at the heart of the Wilderness, resting low down in rough grass at about 8:30 in the morning on Wednesday 23rd.
White letter hairstreak feeds on elm, and has therefore been of conservation concern since the advent of Dutch Elm Disease in the 1970s. According to Butterfly Conservation’s literature on the species they are known to occur as far as a few kilometres from known colonies, but more usually remain within a few hundred metres of their host tree. Apparently there is plenty of young elm growth on campus and White Letter Hairstreak is certainly able to survive on young shoots and small trees (helping it to cling on and even begin to recover in many parts of the country), so it is probable that a small breeding colony exists in Whiteknights Park.
I would be grateful for any other reports of this attractive insect either on campus or elsewhere in Reading, even if they pre-date mine! The flight season has likely just passed its peak but should continue into August, so it is worth keeping an eye out for them for a while yet – and why not submit records of other species to the Big Butterfly Count at the same time?