The Whirligig Beetle is a shiny, black, lozenge shaped beetle which spends most of its time on the surface of still or slow moving waters.
Larvae: More slender bodies with characteristic filaments protruding from the sides of its body. It has pinching mouth parts and tiny claws on the ends of its legs.
Latin name: Gyrinus natator
Size: 5-7mm long.
Overview
The Whirligig Beetle is aptly named for its amusing habit of whirling round and round on the water’s surface when alarmed. This frantic spinning behaviour confuses their predators but they also like to band together in groups for added safety in numbers. Its middle and hind legs are like paddles and allow it to propel itself round ponds and other still waters like a miniature rowing boat. In contrast, its front legs are long and thin and perfect for grabbing and scooping up their insect prey. They also have the ability to trap air under their abdomen for long underwater swims where they scavenge on dead or dying insects. Their most interesting adaptation is their weird looking eyes. Each one has two parts, upper and lower, which allow it to see above and below the water at the same time. This gives them a great view of their environment for keeping an eye on predators and prey alike. And if the water source they’re in dries up or runs out of food, they have strong wings so they can simply buzz off to another pond or stream.
In the garden
These funny little beetles are great additions to any garden pond. Their comical whirling behaviour makes them great to watch and they are great for controlling other insects without causing wider damage to your pond. Mosquito larvae are a particular favourite for the Whirligig Beetle which it gladly gobbles up in numbers during the day while the similar but nocturnal Hairy Whirligig (Orectochilus villosus) feeds on them through the night. A good healthy pond will attract them and a healthy number of submerged plants will provide them with space to lay their eggs.