I've just id'd this little moth from a batch caught at Steps Hill, near to Ivinghoe on July 22nd 2013. It is supposedly common, but for Bucks at least, it is a county first. You are supposed to be able to find the pupae by looking at the old seedheads of Common Fleabane and Spikenard. The pupal case is tough and mixed with frass and chewed seed fragments. Here's a link to the moth: http://ukmoths.org.uk/show.php?id=3456
They give you more collecting tips there as well. Meanwhile here is a photo of its bits.