A device was developed for repetitive sampling of mosquito larvae without undue disruption of the larval habitat. The sampler is a 3-oz. (ca. 100-ml capacity) transparent plastic cup with a hole in the center of its convex bottom. The device is buoyed by corks so that the water level is 15 mm above the bottom rim of the cup and 5 mm above the hole. There was significant correlation between 24-h samples of Aedes albopictus and Culex quinquefasciatus 4th-instar larvae in the larval sampling device and populations in tires. Greater numbers of immature mosquitoes were found per unit surface area of the sampling device than the tire as a whole, demonstrating that immature mosquitoes were trapped by the sampler.