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brown hairstreak

Pictured: brown hairstreak, Thecla betulae

Notes from Jenyns: A single specimen of this insect, much worn & faded, was taken in Sept. 1828, ~ in a small wood at the back of P. Allix’s Esq. ~ Swaffham Prior. ~ Taken in Hatley Wood by Mr Aikin, (formerly Chemist in Cambridge.) ~ Has been taken also at Gogmagog Hills.

200-year trend in Cambridgeshire: Decline to local extinction.

Modern records

Jenyns’ notes show that this species used to be found in several locations across Cambridgeshire. Its larvae rely on blackthorn and suitable sites of blackthorn wood used to be more extensive in the county. However, the species is now thought to be extinct in Cambridgeshire and annual mechanised hedge cutting removing its eggs from the tips of its larval foodplant is thought to be a contributing factor. In the past, hedges were maintained by manual cutting on a much longer cycle, perhaps cut once every 10 years, allowing populations of the butterfly to persist.

Agri-environment schemes, which provide funds to support farmers who manage their land for biodiversity, have encouraged less frequent trimming and are now starting to reverse the national decline of this butterfly. The species is starting to recolonise sites close to Cambridgeshire, offering hope for a natural return.

National records map

Brown hairstreak national records map: