Arboreal Dwellers: Climbing Longhorn Beetles
Japanese pine sawyer beetles Monochamus alternatus hold on convex and rod-shaped structures to be present in their natural habitat (pine trees). On a vertically oriented glass rod, they generate considerable traction forces, corresponding to 7-17 times the body weight of females and males, respectively. These longhorn beetles achieve a proper hold through a combination of interacting parameters: appropriate body alignment and two-sided leg grasping, and generation of normal and friction forces by tarsal pads. The pads are composed of flattened, ribbon-shaped adhesive setae with spindle-shaped, spatulate terminals, acting like adhesive tape. This smart attachment system gives rise to the reconsideration of the ecological and evolutionary background, and provides insights for the development of bio-inspired technical grippers.