Until recently, there were no completely genetic tools that would allow researchers to label just a fraction of a single genetically-defined subset of cells. By labeling fewer cells in a population, it’s easier to visualize individual/non-overlapping cells. While transgenic animals are commonly used to specifically manipulate a cell type of interest in an organism, all cells of that type are affected. Previous tools to overcome this restraint include an AAV-based sparse labeling system where a limiting amount of AAV are injected into the brain of Cre-expressing mice to trigger recombination and expression of a transgene (Lin et al., 2018). However, this system requires precise titration of the AAV. So far, tools to overcome this challenge in Drosophila require heat-shocking the system or using chemical inducers of gene expression (del Valle Rodríguez et al., 2011).