Adult whirligig beetles prey on dead or dying insects, whereas the larvae eat other insects found in the water. Birds and fish are the primary predators of these beetles. A wading bird called the white-faced ibis is the common predator of whirligigs, and another type of animal that feeds on whirligig beetles is the largemouth bass.
Whirligig beetles swarm bodies of water, such as creeks, ponds, swamps and lakes. Large groups of beetles swim rapidly and rotate on the water surface, thus earning whirligigs their name. They actively feed during the daytime. Whirligig beetles are considered beneficial bugs, as they are scavengers that help clean the water surface by consuming dead insects.
Whirligigs watch out for predators in the air and in the water using their two sets of compound eyes. One eye is located above the water surface, while the other is slightly immersed in the water. Once whirligigs notice predators, they escape by swimming very quickly. The beetles clump together in large numbers, typically thousands, to confuse potential predators. However, this enormous gathering enables predators to catch numerous beetles in single swoops.
Whirligig beetles have a chemical defense system that allows them to produce an odor that repels some predators. When faced with danger, they emit testosterone, cortisone and aldehydes, which are chemicals that give them a repulsive taste.