We report an observation of overland dispersal in a flightless aquatic insect during a period of drought-induced stream-drying. We observed an adult giant water bug, Abedus herberti (Hemiptera: Belostomatidae), crawling at 4.6 m/min along a dry stream channel in the Galiuro Mountains, Arizona. We tracked the individual for 130 m and estimate that it moved 240 m from the nearest remaining aquatic habitat. Additionally, we conducted behavioral experiments that confirm that A. herberti can use drying as a cue to initiate movement.