Ruby

I was all set to post something else today - a fresh male Large Skipper resting open-winged on the montbretia in the front garden was probably favourite, though there were a few other candidates too - when I spotted the tiniest flash of rainbow movement on a clump of persicaria. All the jewel wasps - more accurately Chrysid wasps or Chrysididae, but also commonly called ruby-tailed wasps and cuckoo wasps - are tiny (about 5mm long in this case), restless, and fast, and photographing them tends to involve lots of breath-holding, and sends my heart rate through the roof. If I'm ever found face-down and unconscious in a flower bed, that will probably be the reason. But I was helped here partly by the flash I was using, which will freeze an insect's movement at least to some extent, and partly by the fact that the wasp kept pausing momentarily to groom itself. This is why at first glance it appears only to have four legs: the hind pair are currently underneath its wings, cleaning its abdomen.

It's a fool's game trying to identify Chrysid wasps from photos, and the guys at BWARS have no truck with plaintive requests for help, but I think this is a species I've seen before. I had a very similar wasp at the wildlife pond last May, at which point I tentatively named it as Pseudomalus auratus, and I see no reason to change my mind now. I may be wrong, but at least I'm consistent. This species, which is common in the southern half of England, is thought to parasitise certain species of thread-waisted wasps, by laying its eggs inside the type of aphids the hosts leave as food for their own larvae. Some of these aphids will be predated by the unsuspecting host wasps and taken to their nests, at which point the cuckoo wasp eggs hatch inside the aphids, and the emergent larvae kill and eat their hosts. It's not attractive, but it is clever.