Another one, that's my 3rd colony so far, and 2nd locations I've found them in
Just the one spotted on the wall on this occassion, but I would expect more
In 'Water Lily House' greenhouse in Oxford Botanic Gardens.
some info: The Single genus Macronychia comprising 14 species is distributed in Holartic, Neotropic and Oriental (Taiwan) regions. Larvae are inquilines in nests of Sphecoidea (sphecids: (Extemnius cavifrons Thoms.), occasionally in nests of Bombus.
paper (1997): https://www.zobodat.at/pdf/SpixSupp_024_0001-0260.pdf