Paleontologists have discovered a disturbing new species of ancient wasp that restrained its prey using its Venus flytrap-like abdomen before laying eggs in the victim.
The parasite, named Sirenobethylus charybdis after the seawater-swallowing monster from Greek mythology, may represent a whole new family of insects.
S. charybdis lived 98.79 million years ago, during the mid-Cretaceous period, in what is today Myanmar, according to the international research team from China and Denmark.
“The rounded abdominal apparatus, combined with the setae [bristles] along the edges, is reminiscent of a Venus flytrap,” the researchers said in their paper.
“Nothing similar is known from any other insect.”
Qiong Wu
In their work, Taiping Gao of China’s Capitol Normal University and colleagues used micro-CT scanning to study 16 female S. charybdis trapped in amber.
The specimens were all recovered from the Kachin region of northern Myanmar.
Based on the wasps’ body design, the team believes that the species was a “koinobiont”—a type of parasitoid whose young grow in or on a host that is allowed, at least temporarily, to remain alive while serving as a food source.
“Sirenobethylus was probably not able to pursue hosts over longer distances,” the researchers wrote.
“However, the elaborate grasping apparatus indicates that Sirenobethylus was indeed targeting highly mobile prey.”
Qiong Wu
The researchers think that the wasp likely preyed upon small jumping insects to serve as a host for its larvae.
“We imagine it would have waited with the apparatus open, ready to pounce as soon as a potential host activated the capture response,” they wrote.
“Our findings suggest that Chrysidoidea displayed a wider range of parasitoid strategies in the mid-Cretaceous than they do today.”
Xiaoran Zuo
Modern-day parasitoids in the same superfamily—Chrysidoidea—include cuckoo wasps (which, as their name suggests, lay their eggs in the nests of their hosts) and bethylid wasps (which paralyze their prey before hiding the body and laying eggs into the poor victim.)
The team say that S. charybdis should be categorized in a separate family, however, because the ancient wasps have a pattern of veins in their hind wings that is unique.
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Reference
Wu, Q., Vilhelmsen, L., Li, X., Zhuo, D., Ren, D., & Gao, T. (2025). A cretaceous fly trap? remarkable abdominal modification in a fossil wasp. BMC Biology. https://doi.org/10.1186/s12915-025-02190-2