This tiny wasp, about 3mm long, has been making itself at home in our back garden. The first time I saw it, it was hanging on to a garlic mustard leaf during the high winds of last week. As the wind blew, the leaf flung the wasp about, flashing the brilliant red/gold of it's thorax.
My thanks to an expert at iSpot who says this is likely to be a parasitic wasp, Perilampidae.
In this species, the larva rather than the egg-laying female gains access to a host; once there, it continues to burrow into a secondary host - another parasite fly or wasp larva. It makes me think of those wooden Russian dolls, that when taken apart reveal another smaller one, which when taken apart reveals another one, and so on.