Ruby-tailed wasp

The first time I saw this tiny jewel-like wasp was when talking to Peter a couple of weeks ago by the gate to Banks' Pond.  It was only there for a moment and didn't keep still so I didn't get any useful photos.  This time when I stopped by on the off chance it (or another one) was there again, and it sat still for long enough to have its photo taken.

Ruby-tailed wasps are cuckoo wasps, parasites or kleptoparasites of solitary wasps and solitary bees - that is their larvae eat the larvae of the hosts or their food supply.  Chrysis ignita is the most common species but there are several others that are very similar.  It has an armoured body as protection against the defences of the host.  It parasitises mason bees and leaf-cutter bees as well as some solitary wasps.  On the same gate I saw this bee, a leaf-cutter I think but I haven't yet identified it - possibly Megachile centuncularis or M. versicolor.  It may well be the host species.