It hunts large tunnelweb or trapdoor spiders, paralysing them with its sting and storing them in burrows for its larvae to eat alive.

[1] It is one of a number of species named but not described by Adam White, and intended to appear in the series Voyage of the Erebus and Terror, but not in fact being published there.

[4] This name is used for all the New Zealand hunting wasps in the families Eumenidae, Pompilidae, and Sphecidae, such as Pison spinolae and Tachysphex nigerrimus.

Known hosts of P. monachus includes the black tunnelweb (Porrhothele antipodiana), trapdoor (Cantuaria spp.

), funnelweb (Hexathele), sheetweb (Cambridgea foliata), nurseryweb (Dolomedes minor), and vagrant spiders (Uliodon).