In this image, the top two insects are sweetpotato whiteflies (Bemisia tabaci) marked with a fluorescent dye called SmartWater and the bottom two insects are control whiteflies “marked” with water. The insects on the left (panel A) were photographed with white light and the white flies on the right (panel B) were photographed under UV light. Note in the UV photos that the SmartWater-marked individuals showed green fluorescence, whereas the control individuals did not. Photos courtesy of James Hagler and Journal of Insect Science. (Image originally published in Hagler et al 2021, Journal of Insect Science)