Another Tachinid Fly

My second Tachinid fly of the year: Gymnocheta viridis (Diptera: Tachinidae).  This is the only greenbottle fly with long spines on its abdomen that can often be seen sunning itself on tree trunks in the spring time in the UK (Chrysosomopsis aurata = Chrysocosmius auratus is similar but doesn't appear until the summer, see here).

Photo taken in the field below Chazey Wood, near Caversham, UK, on 2012-03-19.