Ruby-tailed wasp

I see these little wasps quite often on sunny days at this time of year.  They are very small and move fast so they are difficult to photograph but even they stop for breath occasionally.  This is a ruby-tailed wasp, probably Chrysis ignita, the commonest of several similar species.  It has a shiny exoskeleton as armour and even the female has no sting.

The ruby-tailed wasp is a kleptoparasite, laying its eggs in the nests of solitary wasps, particularly Ancistrocerus spp. While I was watching it I saw what I think is an Ancistrocerus wasp, the host species.

Ruby-tailed wasps also parasitise solitary bees.  I saw one near the leafcutter bee nest a couple of weeks ago but it took no interest in the nest.