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Abstract: Water striders (Insecta, Heteroptera, Gerridae) have a complex three-dimensional waterproof hairy cover which renders them super-hydrophobic. This paper experimentally demonstrates for the first time the mechanism of the super-hydrophobicity of the cuticle of water striders. The complex two-level microstructure of the surface, including the smallest microtrichia (200–300nm wide, 7–9μm long), was successfully replicated using a two-step moulding technique. The mould surface exhibited super-hydrophobic properties similar to the original insect surface. The average water contact angle (CA) of the mould was 164.7°, whereas the CA of the flat polymer was about 92°. These results show that (i) in water striders, the topography of the surface plays a dominant role in super-hydrophobicity, (ii) very low surface energy bulk material (typically smaller than 0.020Nm−1) is not necessary to achieve super-hydrophobicity; and (3) the two-step moulding technique may be used to mimic quite complex biological functional surfaces. [Copyright &y& Elsevier]