Best time to see: May to end Sep
Key facts
The largest of the diving beetles found in Britain, occupying well-vegetated ponds and lakes
Diving beetles carry air down with them in a cavity in their body, and are strong swimmers and also strong flyers
Young and adults attack fishes and frogs as well as small invertebrates
Recognition
Rounded reddish-brown body with a yellow border, up to 35mm; powerful hind legs fringed with hairs to aid swimming
The males have smooth wing cases and suction pads on their front legs; females' wing cases are ridged
Often fly at night to find new habitat, sometimes landing on glass rooves and wet roads by mistake
Lifecycle
Females lay their eggs in cavities that they cut into the stems of aquatic plants above the water line
The eggs hatch after several weeks into scorpion-like larvae with large jaws
Pupate and emerge as adults during the summer, and can live for several years
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© Tony Gunton