Great Diving Beetle - Dytiscus marginalis


One of our largest beetles, this species has a dark, olive-brown, almond-shaped oval body, about three centimetres long. The pronotum is completely bordered by a yellow margin - one of the key features that enables this species to be recognised in the field.  The wing cases of the female are ribbed whilst those of the male are smooth.

Identification difficulty

These beetles live in fresh water, either still or slow-running, and seem to prefer water with vegetation.

When to see it

All year round. Great Diving Beetles periodically come to the surface, extruding the tip of the abdomen to replenish an air supply kept under the wings. They are able to leave the water and fly off to colonise new ponds, sometimes landing in error on shiny car roofs or cold-frames in mistake for a water surface.

Life History

Predatory as adults and larvae, eating anything they can tackle, including other water insects, tadpoles and even very small fish. The larvae are yellowish brown in colour, growing to about five centimetres in length, and possess a fierce pair of jaws - handle with care! They need damp soil by the edge of the water in order to pupate successfully.

UK Status

Quite common and widespread in Britain.

VC55 Status

Fairly common in Leicestershire and Rutland. There were a total of 66 VC55 records for this species up to March 2015.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map