How sharpshooter insects fling their droplet pee

Sharpshooters are sap-feeding insects that ingest up to 300 times their body weight of nutrient-poor xylem fluid per day to extract sufficient nutrients. Unlike other creatures that rely on jetting and dribbling to expel their liquid waste, sharpshooter insects catapult their water-based excreta one droplet at a time using a resilin-powered stylus. In this presentation, we show that during the droplet ejection, sharpshooters exploit the concept of superpropulsion, where the ejected elastic droplets take off at a speed higher than the speed of the actuating stylus. This is achieved by tuning the temporal dynamics of their catapulting appendage relative to the natural vibration frequency of the droplet projectiles.  Through a mathematical analysis and computational approach, we explore the physical limits of such a unique droplet propulsion strategy and show why it is energetically favorable for these insects to fling their droplet excreta. Using dimensionless analysis, we show how biological organisms living in a world governed by surface tension develop exquisite strategies to overcome capillary adhesion during fluidic ejection.