Parasite on Polistes sp.
Thanks to Mattia Menchetti (Italy) for ID (and noticing it in the first place).
Sessile twisted-wing parasite in a wasp's abdominal segment. The animal is really unclear in these images, but you can see the bulge clearly in the first picture, and (barely) the whole sticking-out-part in the second. Unfortunately, taking pictures of a very small part of a big, wriggling wasp in a reflective plastic bag with a clumsy macro lens is rather difficult.
The wasp's observation is https://www.inaturalist.org/observations/2240722 .
I sometimes caught insects in net temporarily, and put the really really flighty and dangerous ones in a plastic bag for ease of picture-taking. They were released.
Strepsiptera ( del griego strepsis, "curvado", "retorcido" y pteron, "ala"), conocidos comúnmente como estrepsípteros es un orden de insectos diminutos, parásitos obligados de otros insectos. Se conocen unas 500 especies repartidas en dos subórdenes.