We have analysed the relationships between structure and mechanical properties cocoon morphology of B. mori, and developed a model, based upon generic fibroin and sericin properties, which shows quantitatively that properties are dictated largely by the amount of sericin bonding between the fibres [7]. This bio-inspired model can be applied to other nonwoven fibre composite structures, such as paper, domestic fabrics, and electrospun nanomats, as well as some particulate composites such as concrete and polymer bonded explosives, which are technologically important materials.