I've never seen it before, it has a small spikelike attachment on the back. Picture from today,29-07-2011, on Jacobaea vulgaris, The Netherlands, southern part. It was about 4,5-5mm. Is an id possible?
Kind regards,
Pietsje Fleurbaaij
Edit: From the Dutch forum of www.waarneming.nl I know now that it is Elampus panzeri!