A ruby-tailed burglar

Parasites seem to be dominant over hosts in the bee house this year.  I watched a mason wasp putting the finishing touches to her nest, blocking up the entrance with mud.

I wasn't the only watcher.  There were several ruby-tailed wasps waiting around.  They are cuckoo wasps and lay their eggs in the nest of other solitary wasps.

One in particular taking a close interest in what was going on.

Eventually the mason wasp was satisfied and after a last look round she flew away.

Within a few minutes the ruby-tailed wasp had returned to the nest and started to chew out the mud seal.

It took 25 minutes of chewing.

You can see her ovipositor is extended ready for action.

Then she suddenly turned around to lay her own egg in the nest.

That took only a few moments and she was off, perhaps to seek another victim.

As I understand it, the mason wasp lays a series of eggs in different cells along the length of the nest, separated by mud wall in the same was a a mason bee so I presume the ruby-tailed wasp, with a short ovipositor, can only parasitise the front cell.  I hope I'll be watching to see what emerges next year.

PS.  The photos are attracting a lot of attention on Facebook.  The experts on the BWARS page say the mason wasp is Symmorphus bifasciatus and the ruby-tailed wasp is likely to be Chrysis angustula.