The venom that velvet ants inject through their stinger has an unknown composition. According to one researcher, the painfulness of the sting of "Dasymutilla klugii" outscored 58 other species of stinging insects tested; the only species this researcher rated as having a more painful sting were the "Paraponera clavata" (bullet ant), "Synoeca septentrionalis" (warrior wasp), "Pepsis" spp. and "Hemipepsis" spp. (tarantula hawks). In an experimental setting, only two lizard species (one whiptail and one side-blotched lizard) attacked a velvet ant it was exposed to. In both cases the velvet ants were exhibiting rapid lateral and vertical movements to ward off an attack. Once the attack occurred the velvet ants would immediately sting the lizards. This sting resulted in the dropping of the ants in both cases and avoidance for the remainder of the trial. The side-blotched lizard was found dead in its tank 24 hours later. The side-blotched lizard is a natural predator of velvet ants, while the whiptail is not. To test the aposematic coloration on birds, mealworms were painted to resemble a velvet ant. During these trials, none of the painted mealworms were consumed, while all the control mealworms were consumed immediately. However, the painted mealworms were attacked by the birds, but the birds immediately ceased the attack. These experiments provide evidence that the aposematic coloration of velvet ants causes their predators to hesitate, acting as a visual defense mechanism.