Verdaguer Mallorqui, M.; Vincent, J. F. V.; Liston, A.; Blagoderov, V.; Desmulliez, M. P. Y.

The female sawfly (Insecta: Hymenoptera, Symphyta) uses a double reciprocating saw-like ovipositor to cut into plant tissue, laying its eggs within the cut. We have identified a passive selective cutting mechanism in which the saw discriminates between material properties of the plant tissue without active sensing or external control. The mechanism balances effective cutting with minimal collateral damage to either the plant or the saw. Scaled-up models of the saw cutting into experimental substrates (agar and ballistic gelatine) across a range of stiffnesses reveal an ultimate stress threshold above which substrates are displaced rather than incised. This depends on the interaction between the shape of the saw teeth and the substrate properties and is consistent across multiple species of sawfly. These findings suggest a novel surgical tool design with high selectivity of cutting and reduced collateral damage.