To enable NMR metabolomic studies in the model organism Caenorhabditis elegans, large-scale cultures are a prerequisite to produce small molecule extracts of sufficient concentration for analysis. Extensive growth results in a variable distribution in the distinct life stages of C. elegans (L1, L2, dauer, L3, L4, young adult and adult) that are present at any given time. The COPAS Biosorter, a specialized large particle flow cytometer, collects some phenotypic data of such cultures. While the sorter allows us to count and identify the normal developmental stages of sampled worms based on time of flight (TOF) and extinction (EXT) measurements, we cannot intuitively quantify how many dead or dauer worms result from these dense cultures. We treated samples with a fluorophore-conjugated lipid analog that has been previously shown to insert into the epicuticular layer of a normally developing nematode, but is excluded by dauer larvae. Combined with dauer-specific morphology data collected by the Biosorter, we are able to estimate the number of dauer worms present in a dauer “spiked” sample by calculating the number of non-fluorescent events that appear within the size and density range of dauer worms. This poster depicts our efforts to develop a robust, high-throughput assay for the presence of dauer larvae that utilizes the detection capabilities of the COPAS Biosorter to exploit biophysical and morphological differences between normally developing worms and dauer larvae. Along with fluorescent vitality dyes that can simultaneously identify the number of dead animals present in a sample, we aim to collect an inclusive set of phenotypic data from a single experiment that can be related to the resulting metabolite profile of each culture.