Temperature can profoundly affect many physiological processes, including muscle performance. Many ectotherms appear sensitive to this relationship, choosing times and locations of activity permitting high body temperatures and, thus, quick escape from predators. High body temperatures, however, can lead to dehydration, which in turn affects muscle performance. Striped bark scorpions Centruroides vittatus Say 1821 provide an ideal model for assessing the effects of temperature and water loss on two potentially important antipredator behaviors, sprinting and stinging. Scorpions had significantly higher sprint speeds at warmer temperatures, with males significantly faster than females. Additionally, sting latency was longer and sting rate lower when scorpions were cooler. Intriguingly, females appear capable of stinging at a higher rate than males. Desiccation allowed the scorpions to sprint significantly faster than control (hydrated) scorpions, probably due to weight loss. The influence of temperature on sprinting and stinging might thus explain bark scorpions' preference for maintaining high body temperatures during periods when they are exposed to predation. When inactive, however, scorpions may benefit from maintaining lower body temperatures to decrease resting metabolic rate and desiccation.