Hobbies And Interests
Larvae
Immature whirligig beetles are up to an inch long, with lateral extensions on their abdomen and four hooks at one end. Larvae also have pointed pincher-shaped mouth parts. They spend most of their time at the bottom of a pond or stream, and prey on smaller aquatic creatures, especially insects. They are seldom seen by humans.
Adult
Adult whirligig beetles spend most of their time on the surface of the water, and feed on organisms living there. Unlike their completely carnivorous larvae, adult whirligig beetles are also scavengers. They eat insects and other organisms smaller than they are, and also consume floating plant and animal debris.
Hunting
The whirligig beetle hunts by holding its long forelegs out in front of its body, ready to seize prey. It has two sets of eyes--one above the surface of the water and one below--which allow it to stay aware of potential predators without losing sight of its prey. When potential food comes close enough, the whirligig beetle simply grabs it.
Grouping
Whirligig beetles do not spend much time alone, as it increases their risk of predation. Instead, they tend to group on the surface of the water, creating large "mats" of beetles. Hungry beetles spend more time on the outside of the group, where the chances of encountering prey are higher, but the risk of predators is greater.
Expert Insight
According to Behavioral Ecology and Sociobiology, whirligig beetles do not stay in the same group at all times. Beetles spend time in groups during daylight hours, sometimes even grouping with whirligig beetles of other species. At night, the beetles disperse for more active hunting. Before daybreak, they form long lines, following other beetles to join into new groups. This behavior allows them to avoid being eaten by fish during the day, and prevents individual beetles from needing to find their original group.