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Great silver water beetle

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This enormous water beetle is as rare as it is impressive.

Scientific name

Hydrophilus piceus

When to see

All year

Top facts

Category

Stats

Up to 4.8 cm
Classed as Near Threatened on the GB Red List

About

The great silver water beetle is one of the UK's largest beetles. It lives in ditches and pools with reedbeds and lots of aquatic vegetation. Although it spends most of its time underwater, it needs to return to the surface regularly to breathe and top up the air supply stored in a bubble against its body. It is not technically classed as a 'diving beetle' - it is a species of scavenger water beetle. They have clubbed antennae, whilst diving beetles have filamentous antennae.

Great silver water beetles are strong fliers and, like many other beetles, may sometimes be attracted to moth traps. However, they are rare in the UK and only found in a few distinct locations.

What to look for

An enormous black water beetle. Viewed from above, it is oval shaped, but from the side you can see the underside is flattened, unlike the rounder diving beetles. Its clubbed antennae also help separate it from diving beetles. It has long hind legs, each with a distinctive long, sharp spine protruding from the inside. In water, it holds a film of air against its belly, creating a silvery sheen that gives the great silver water beetle its name.

Where to find

Mainly found in the Somerset Levels, East Anglia and southeast England.

Did you know?

The larvae of great silver water beetles are predators and feed on water snails. They leave characteristic bite marks on empty snail shells.