An interesting insect

While wandering up the block today (in a failed search for orchids) I noticed a small construction hanging off a Kunzea ericoides (aka Burgan) bush.  The leaves of the Burgan give an indication of scale.

An alert observer will note an insect on the bottom of the construction.  When we first arrived there were several such insects around but most disappeared before I could tether small dog and get the camera out and set up.

Cropping the image to show the insect reveals this complex beast.  It also gives a close-up of the construction.

My interpretation of this was a wasp of some sort on the outside of its nest.  On seeking advice from Roger Farrow he commented that in fact "it is a species of Podagrion (Monodontomerini:Torymidae: Chalcidoidea: HYMENOPTERA).  All species are parasitoids of mantis egg cases, which is what your "nest" is: the female wasp is recognised by the enlarged dentate femora.  Very few mantis egg cases escape some level of parasitism.. Emerging mantis nymphs tear their way out and do not make holes."

The key to identifying this was to recognise that the construction is a mantis egg case rather than, as I had thought, a wasp nest.  Then check the parasites of the egg cases!  Many thanks Roger. 

I returned to the area a couple of days later and took a few more pictures.  The first image below shows at least three wasps on the egg case(although the lowest one didn't move, so I suspect it was not at all well).

In the second image I cannot pick out an ovipositor or dentate femur on the lower wasp so suspect it might be a male.