Question Newly Described 'Venus Fly Trap' Parasitic Wasp

The Venus Flytrap Wasp

Summary:
An amber-preserved species of wasp from the mid-cretaceous (99 million years ago) species has been described. The newly described species belongs to the genus Sirenobethylus, has a unique abdominal adaptation that resembles a venus fly trap. This apparatus is hypothesized to have been used as a tool to immobilize potential hosts during oviposition.

From the ABC NEWS Report:
‘Ancient parasitic ‘Venus flytrap’ wasp found preserved in amber’
By Julia Jacobo
Published March 27th, 2025
ABC NEWS

‘Researchers at the Natural History Museum of Denmark and Capital Normal University in China analyzed 16 female specimens preserved in amber using micro-CT scanning. They estimate the specimens, collected from the Kachin region in northern Myanmar, date to 98.79 million years ago during the mid-Cretaceous period.’

‘The morphology of the wasps indicates that they were parasitoids, or insects whose larvae live as parasites inside their hosts before eventually killing them, the researchers said. The wasps likely allowed their host to continue growing while feeding on it.’

‘S. charybdis was likely unable to pursue prey over long distances, and the researchers speculate that they waited with the apparatus open for a potential host before activating the capture response.’

‘Cuckoo wasps and bethylid wasps are modern-day parasitoids within the same superfamily, Chrysidoidea, according to the paper.

‘A unique pattern of veins in the hind wing of the extinct S. charybdis also suggests that the species may belong to its own family, the Sirenobethylidae, the researchers said.’

From the Research Article:
‘A cretaceous fly trap? remarkable abdominal modification in a fossil wasp’
By Qiong Wu, Lars Vilhelmsen, Xiaoqin Li, De Zhuo, Dong Ren & Taiping Gao
Published March 27th, 2025
BMC Biology 23, Article Number: 81 (2025)

Abstract:
Background:
‘Carnivorous insects have evolved a range of prey and host capture mechanisms. However, insect predation strategies in the fossil record remain poorly understood.’

Results:
‘Here, we describe †Sirenobethylus charybdis n. gen. & sp., based on sixteen adult female wasps in Kachin amber from the mid-Cretaceous, 99 Mya (million years ago), and place it in Chrysidoidea: †Sirenobethylidae n. fam. The fossils display unique morphological modifications on the tip of the abdomen consisting of three flaps from the modified abdominal sternum 6 and tergum and sternum 7; the lower flap formed from sternum 6 is preserved in different positions relative to the other flaps in different specimens, indicating that they form some sort of grasping apparatus. Nothing similar is known from any other insect; the rounded abdominal apparatus, combined with the setae along the edges, is reminiscent of a Venus flytrap. Phylogenetic analysis suggests that the new family is a separate lineage close to the base of Chrysidoidea.’

Conclusions:
‘Sirenobethylus probably was a koinobiont parasitoid wasp; the abdominal grasping apparatus may have been used to temporarily immobilize the host during oviposition. The new fossils suggest that Chrysidoidea displayed a wider range of parasitoid strategies in the mid-Cretaceous than they do today.’

Figure 1
'†Sirenobethylus charybdis sp. nov., holotype (specimen CNU-HYM-MA2015124) female. A Dorsal view as preserved. B The tip of abdomen and ovipositor in ventral view, showing trigger hairs (black arrows). C The tip of abdomen and ovipositor in lateral view, showing trigger hairs (black arrows), ovipositor (orange arrow) and groove on the sternum 7 (blue arrow). D Habitus reconstruction. Scale bars: A 0.5 mm; B 0.3 mm; C 0.2 mm. Abbreviations: S6 sternum 6; T7 tergum 7; S7 sternum 7'

Sources:

Jacobo, A. (2025, March 27). Ancient parasitic ‘Venus flytrap’ wasp found preserved in amber. ABC News. abcnews.go.com/International/ancient-parasitic-venus-flytrap-wasp-found-preserved-amber/story?id=120130109

Wu, Q., Vilhelmsen, L., Zhuo, D., Ren, D., & Gao, T. (2025). A cretaceous fly trap? Remarkable abdominal modification in a fossil wasp. BMC Biology, 23(1), 81. bmcbiol.biomedcentral.com/articles/10.1186/s12915-025-02190-2