The relationship of hellgrammites (Corydalus cornutus) with physicochemical variables and the co-occurrence of hellgrammites with crayfish, caddisflies, and black flies at the plot level was assessed in summer 2025 as part of a larger three-year study. Sampling was conducted in five central Ohio streams in June and July. Results indicated that Clear Fork River sites had the greatest hellgrammite abundance and the Alum Creek, Big Walnut Creek, and Kokosing River sites exhibited the lowest abundance. Statistical analyses revealed a positive correlation between hellgrammite density and water temperature (p = 0.031) and a negative correlation with dissolved oxygen (p = 0.001). Hellgrammite occurrence was also negatively correlated with pH (p = 0.027) and dissolved oxygen (p = 0.004). Log transformed head capsule width showed positive correlations with conductivity (p = 0.050) and water velocity (p = 0.007), and a negative correlation with crayfish density (p = 0.037). Additionally, head capsule width exhibited a negative correlation with crayfish density (p = 0.037) and none of the hellgrammite response variables were correlated (p > 0.05) with caddisfly and blackfly occurrence. Our results indicated that hellgrammite density and occurrence within riffles of central Ohio rivers are affected by physicochemical variables, and hellgrammite body size is associated with crayfish density. Future analyses will involve investigating the relationships between hellgrammites and nutrient concentrations and the long-term population trends of hellgrammites.