An important hypothesis concerning the role of aggregation in the antipredator defense of aposematic insects is that a group projects a larger aposematic signal to a predator. The nearly exclusive use of birds as model predators may be leading us to over-emphasize the importance of signal amplification as an explanation for the gregarious behavior of aposematic insects. Ambush (sit-and-wait) predators such as amphibians and praying mantids make predatory decisions relying primarily on prey movement, and secondarily on prey size, with prey color being less important. Therefore, we tested the interaction of aposematic coloration and gregarious behavior in insect defense from frogs. We offered frogs four types of mealworm prey: (1) cryptic and solitary, (2) cryptic and gregarious, (3) aposematic and solitary, and (4) aposematic and gregarious. The frogs ate aposematic and gregarious prey significantly later than they ate cryptic and gregarious prey and cryptic and solitary prey. Our results support the hypothesis that aposematic coloration in gregarious prey, but not in solitary prey, can function to produce a sufficient aposematic signal to delay attack by an ambush predator. This result was not due to predator learning. Hence, the antipredator benefits of aposematic coloration in aggregated prey may function in encounters with a wide range of predators, including frogs.