Ectotherms often avoid abiotic stress by moving among microclimates. Such behaviors may allow populations to persist within refugia even when macro-conditions are stressful. Whether aquatic insects exploit locally available microclimates, however, has received little attention. For stream insects, life in water is shaped by the scarcity of oxygen. In principle, behavior may allow insects to mitigate oxygen shortages – by choosing local regions of lower temperature, higher dissolved oxygen, and higher flow velocity in ways that increase ratios of oxygen supply:demand. However, because water has such a high heat capacity and is typically well-mixed, temperature and oxygen are not likely to vary strongly over small spatial scales – although they can vary in some systems due to upwelling groundwater or inputs from other sources. By contrast, flows are highly heterogenous, often ranging from < .05 m/s within the substrate to > 1 m/s in the free-stream environment. Exploiting micro-variation in flow may, therefore, be the most reliably available option for aquatic insects to mitigate oxygen shortages. Here, we examine choice-preferences of giant stonefly nymphs, Pteronarcys californica, to experimental gradients in temperature, oxygen, and flow. In alignment with our predictions, P. californica nymphs show little ability to exploit laboratory gradients in temperature and oxygen; they made weak choices and only when presented with unrealistically large gradients. Flow-choice experiments are ongoing. We predict that stonefly nymphs will exploit micro-variation in flow much more readily – choosing higher water velocities when temperatures are high or when oxygen levels were low. These behaviors may allow stoneflies, and other aquatic nymphs, to survive in streams during bouts of low-oxygen availability, which may increase in frequency under climate change.