Incident sunlight reflecting a concentrated bright shimmer pulled my attention to an object floating in water. A small chalcid wasp, ±4 mm in length, floated submerged in water. It turned out to be a female Perilampus aeneus [1,2], a parasite on Curculionidae (Coleoptera), Tenthredinidae (Hymenoptera), Tortricidae (Lepidoptera)  and Tachinidae (Diptera), Blepharipa pratensis and Parasetigena silvestris .
During examination with a magnifying glass it became clear she wasn’t dead yet but not much life was left in her. Shortly after she passed away and is now part of garden collection.
References1 Nederlands Soortenregister
2 MITROIU, Mircea-Dan; KOUTSOUKOS, Evangelos. Perilampus neglectus and other neglected species: new records of Palaearctic Perilampidae (Hymenoptera, Chalcidoidea), with a key to European species of Perilampus. Journal of Hymenoptera Research, 2023, 96: 57-99.
3 ZANKL, Thomas; SCHAFELLNER, Christa; HOCH, Gernot. Parasitoids and pathogens in a collapsing Lymantria dispar (Lepidoptera: Erebidae) population in Lower Austria. Journal of Applied Entomology, 2023.