Great Diving Beetle
The great diving beetle, is a large aquatic diving beetle native to Europe and northern Asia, and is particularly common in the UK & Ireland. The great diving beetle, true to its name, is a rather sizable insect. The larvae can grow up to 60 millimeters (2.4 in) in length, while the adults are generally between 27–35 millimeters (1.1–1.4 in). These beetles live in fresh water, either still or slow running, and seem to prefer water with vegetation. They are dark-coloured (brown to black) on their back and wing cases (elytra) and yellow on their abdomen and legs. The male's wing cases are shiny, while those of the female are finely grooved. A voracious predator, this beetle hunts a wide variety of prey including small fish & tadpoles.
They are able fliers, and fly usually at night. They use the reflection of moonlight to locate new water sources. This location method can sometimes cause them to land on wet roads or other hard wet surfaces. Before they dive, they collect air bubbles in their wing cases. The jaws of a great diving beetle are strong compared to their body size & if you see one, don't pick it up because it will bite you.