A fluorescent dye designed for use as an anti-theft tool and aid in forensic criminal investigations also works well for marking insects in mark-release-recapture efforts, a new study shows. Shown here are western tarnished plant bugs (Lygus hesperus) under white light (left) and ultraviolet light (right). The individuals in the top row were marked with a fluorescent dye called SmartWater; those in the bottom row were control specimens “marked” with water. (Image originally published in Hagler et al 2021, Journal of Insect Science)