Why do insects never loose their footing?

Insects possess an endogenous adhesive that lets them walk vertically along smooth surfaces. The bottoms of their feet secrete the substance, which fills in the microscopically small irregularities in the surface. For good measure, even the tiniest hairs on the bottom of their feet hook onto these uneven areas. If they want to continue walking, they must loosen their feet slowly, like separating a Velcro fastener. The adhesive’s chemical composition enables it to be applied again and again.