Great diving beetle
(Dytiscus marginalis)
The larvae of the great diving beetle can grow up to 60 mm in length. The adult beetle is about half this size. Both live in still or slow-moving freshwater and are voracious predators that can eat a range of aquatic organisms including tadpoles. The larvae are fully aquatic with large jaws, while the adult looks like a very large beetle and can fly (at night) as well as swim underwater.
The great diving beetle is relatively common locally.
Fascinating fact:
Do not try to pick these beetles up – they bite.
The female beetle lays eggs singly in stems of aquatic plants in spring, which hatch into aquatic larvae. They leave the water to pupate in adjacent wet areas and emerge as young adults in autumn. They remain buried in winter and emerge in the spring.
Did you know
There are six British species of diving beetles, of which this is the largest and most common.