Adhesion and Suction Functions of the Tip Region of a Nectar-drinking Butterfly Proboscis

In this study, we investigated the dynamic functions of the tip region of the butterfly proboscis through which liquid is sucked during liquid feeding. The microstructures and flow patterns in the tip region of the proboscis were in vivo analyzed. The tip region can be divided into two functional sections: namely adhesion and suction sections. The liquid adheres to the adhesion section during liquid suction. Although the tip region has numerous slits connected to food canal of the proboscis, liquid is mainly sucked through the suction section, which section is submerged in the fluid pulled by the adhesion section and then successfully imbibes liquid. To check the dynamic functions of the tip region, we fabricated a suction tip model having adhesion and suction parts. The in vitro model experiments show that the hydrophilicity of the adhesion part and the existence of the suction inlet improve the liquid uptake driven by a suction pump. This study may provide insights for the biomimetic design of nectar-feeding butterflies.