Silicon (Si) is increasingly being recognised as an essential element for plant health to tackle abiotic stresses, and it may also deter herbivores from plant-feeding, as a result of tooth wear caused by silica phytoliths. However, direct quantitative evidence for Si-induced wear is scarce. In this study, we subjected pristine Atta vollenweideri ant mandibles to multiple wear treatments on Hordeum vulgare barley leaves, grown with either 0-, 2- or 4-mM Si-supplemented hydroponic media, resulting in varying Si concentrations in the leaves. Pristine mandibles were collected from freshly eclosed ants that had never engaged in foraging, and wear treatments were conducted by driving isolated mandibles through leaf lamina at a constant speed using custom-built clamps attached to a motor stage. To quantify the effects of mandible wear, before, in between, and after each treatment, the forces required to cut standardised PDMS sheets were measured using a custom-built fibre optic force transducer; after 300 mm barley cut length, the cutting forces on PDMS increased significantly across all Si conditions; this force increase, however, was not consistent across Si concentrations, such that the change in cutting force per leaf length cut was 174% larger on 4 mM compared to 0 mM leaves. These results indicate that mandible abrasion may be facilitated by the mechanical contact between cutting edge and silica phytoliths. As increased mandible wear is likely of significant detriment to lifetime foraging efficiency, targeted Si-supplementation may be an effective yet ‘green’ agricultural strategy to provide protection against insect herbivores.