Common Backswimmer

Notonecta glauca

Statistics

Taxonomic family: Notonectidae

Length: 1 to 1.6 cm

Average life span: upwards of 1 year

Juvenile stage (in water): 2 to 3 weeks

Adult stage (out of water): 1 year

When To See

The larvae hatch from early summer onwards and two generations can hatch per year. The beetles are found all year round but are most active during warmer weather.

Photo credit: Neil Phillips

Habitat

Most common in ponds and lakes, they can be found in some slow flowing rivers and pools. They are carnivores, hunting smaller insects, flies and such that land on or are in the water. Kind of like a spider, they use the surface tension of the water to feel for vibrations from their prey and can recognise that movements that are above 70hz are worth investigating as potential food.

How To Identify

Large reddish eyes. Light brown body in the shape of a boat, with large powerful hind legs which it uses as paddles when swimming upside down. Can have a silvery appearance due to the trapped air bubbles on its lower surface that allow it to breathe.

Seen It?

Been kicking about in your local river and come across one of these invertebrates? Not sure? Share it with us at trust@forthriverstrust.org, we enjoy chatting about inverts with you.