Researchers at Heriot‑Watt University studied how female sawflies lay eggs in plants. The team found the insects’ ovipositor behaves like a biological reciprocating saw, instinctively knowing when to cut and when to push material aside. The sawflies must avoid killing the plant so it remains alive to feed the larvae. Electron microscopy and 3D imaging helped map the cutting-teeth geometry, showing that small serrations work with larger protrusions to create the selective action. The mechanism is passive, relying on tooth shape and material properties rather than sensors or electronics. To test the idea further, the researchers scaled the cutting system about 400 times and applied it to materials that mimic human tissue, finding the device operated at a similar ultimate stress threshold and displaced only the softer material.

Professors Marc Desmulliez and colleagues say the discovery could have important implications for surgical practice. In many operations, surgeons work in blood-filled environments with limited visibility and a risk of damaging vital structures. A tool inspired by this natural mechanism could cut precisely where needed while automatically avoiding critical tissues. The researchers say further input from surgeons is needed as the concept moves towards clinical use. The work was published in Bioinspiration and Biomimetics by an international team.