The Polideini is becoming one of my favourite tribes because they have such unusual features. Most tachinids have a disc-like, hairy lappet covering the metathoracic spiracle (the hind one on the thorax) but the Polideini all have paired hairy lappets that don’t quite meet at the top, leaving a little hole. They also have a huge anepimeral (pteropleural) bristle too, making them quite distinctive and easy to spot amongst other grey and anonymous tachinids.
The following photos show 3 specimens that key close to the genus Lypha (with a very distinctive arrangement of katepisternal bristles where the middle bristle is closest to the posterior with both middle and posterior being slightly ventral to the anterior. The other keys close to Chrysotachina.
EDIT (28/11/2010): Monty has let me know that the “Lypha” will not actually be Lypha because this is a genus of high altitude. However in the key what runs to Lypha is likely to be a mixture of Polideini.