Abstract

Every day, and most of the time without even noticing it, we are surrounded by one of the most successful groups of animals: insects. They have been running, crawling and flying around the earth since before the dinosaurs, they can survive in rain-forests, deserts and even in Antarctica. Insects can stick to almost all surfaces, carry several times their bodyweight, perform astonishing jumps and even migrate over thousands of kilometres. How do they do this?

One of the keys in understanding the insects’ secrets of evolutionary success is looking at the biomechanics of their versatile exoskeleton made of cuticle. This talk will give a brief introduction to the biomechanics of insect feet and will then focus on the mechanical properties of insect cuticle, in particular the cuticle of locust legs and wings.

Recent experiments show that the cuticle found in the locust legs has an almost unique combination of high fracture toughness with relatively low structural stiffness, making it one of the toughest of all natural materials. The wing membrane however is not very tough, as one would expect in a durable high-performance material. Instead, the wings achieve their high fracture resistance with the help of their characteristic vein pattern. Interestingly, almost all veins of the locust hind wing show the fracture-mechanic’s optimal spacing, which corresponds to the so called “critical crack-length” of the membrane. This evolutionary adaptation combines high toughness with a minimum of weight within the locust’s hind wing structure.

These findings are not only fascinating from the biologists point of view: understanding more about insect biomechanics might also inspire the development of novel biomimetic adhesives, as well as lightweight and durable composite materials.