Ladybird beetles are high-mobility insects and explore broad areas by switching between walking and flying. Their excellent wing transformation systems enabling this lifestyle are expected to provide large potential for engineering applications. However, the mechanism behind the folding of their hindwings remains unclear. The reason is that ladybird beetles close the elytra ahead of wing folding, preventing the observation of detailed processes occurring under the elytra. In the present study, artificial transparent elytra were transplanted on living ladybird beetles, thereby enabling us to observe the detailed wing-folding processes. The result revealed that in addition to the abdominal movements mentioned in previous studies, the edge and ventral surface of the elytra, as well as characteristic shaped veins, play important roles in wing folding. The structures of the wing frames enabling this folding process and detailed 3D shape of the hindwing were investigated using microcomputed tomography. The results showed that the tape spring-like elastic frame plays an important role in the wing transformation mechanism. Compared with other beetles, hindwings in ladybird beetles are characterized by two seemingly incompatible properties: (i) the wing rigidity with relatively thick veins and (ii) the compactness in stored shapes with complex crease patterns. The detailed wing-folding process revealed in this study is expected to facilitate understanding of the naturally optimized system in this excellent deployable structure. Significance Hindwings in ladybird beetles successfully achieve compatibility between the deformability (instability) required for wing folding and strength property (stability) required for flying. This study demonstrates how ladybird beetles address these two conflicting requirements by an unprecedented technique using artificial wings. Our results, which clarify the detailed wing-folding process and reveal the supporting structures, provide indispensable initial knowledge for revealing this naturally evolved optimization system. Investigating the characteristics in the venations and crease patterns revealed in this study could provide an innovative designing method, enabling the integration of structural stability and deformability, and thus could have a considerable impact on engineering science.

As observed in the design of antenna reflectors and rocket bodies, both flat and 3D-shaped honeycomb cores are used in the field of aerospace engineering. This study illustrates a new strategy to fabricate arbitrary cross-section honeycombs with applications of advanced composite materials by using the concept of the kirigami honeycomb, which is made from single flat sheets and has periodical slits resembling origami. The authors also describe a method of applying this technique to advanced composite materials. Applying the partially soft composite techniques, 3D shaped composite honeycombs are manufactured, and some typical samples are shown with their folding line diagrams.

This study introduces the design and manufacturing of a wingbox based on a cellular hexagonal morphology and produced using kirigami techniques. The wingbox is manufactured in autoclave-cured woven Kevlar fabric using ply-cutting patterns designed around an airfoil profile. The cellular wingbox can be completely or partially folded, providing some shape-adapting capabilities for possible morphing applications. A numerical and analytical evaluation of the torsional stiffness of the wingbox with novel elastomeric face skins is also performed.

Significance: Rove beetles are known to fold their wings in the most complicated and sophisticated ways that have right–left asymmetric patterns. This asymmetric folding can confer both high deployment capability and high storage efficiency, and therefore has a great deal of potential for engineering applications. However, the detailed folding mechanisms have been unclear because of the difficulty of observing of the folding processes. This study used a high-speed camera to observe the wing folding movements of rove beetles. The results show that these characteristic asymmetrical patterns emerge as a result of simultaneous folding of overlapped wings. The specific crease patterns of respective wings and detailed folding motions in each folding sequence are also described here.